The authors acknowledge financial support from the Engineering and Physical Sciences Research Council, UK under the Program Grant 'Supercritical Fluid Electrodeposition' (EP/J016276/1). J.S. and R.J.K. are indebted to the Warwick Centre for Analytical Science (EPSRC funded Grant EP/F034210/1). Additionally, we are indebted to Drs. Zheng Liu and Kazu Suenaga who provided the top right part of Panel d of Figure 1, which originally appeared in Microsc. Semicond. Mater. 2008, 120, 213-216 (used with permission).

<ol>
	<li>Raman, C. V., Krishnan, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+type+of+secondary+radiation.">A new type of secondary radiation.</a> Nature. 121, 501-502 (1928).</li><li>Gudiksen, M. S., Lauhon, L. J., Wang, J., Smith, D. C., Lieber, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+nanowire+superlattice+structures+for+nanoscale+photonics+and+electronics.">Growth of nanowire superlattice structures for nanoscale photonics and electronics.</a> Nature. 415, 617-620 (2002).</li><li>Hisamoto, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FinFET-a+self-aligned+double-gate+MOSFET+scalable+to+20+nm.">FinFET-a self-aligned double-gate MOSFET scalable to 20 nm.</a> IEEE T Electron Dev. 47, 2320-2325 (2000).</li><li>Hurst, S. J., Payne, E. K., Qin, L., Mirkin, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multisegmented+one-dimensional+nanorods+prepared+by+hard-template+synthetic+methods.">Multisegmented one-dimensional nanorods prepared by hard-template synthetic methods.</a> Angew Chem. 45, 2672-2692 (2006).</li><li>Ishii, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+observation+of+Tomonaga-Luttinger-liquid+state+in+carbon+nanotubes+at+low+temperatures.">Direct observation of Tomonaga-Luttinger-liquid state in carbon nanotubes at low temperatures.</a> Nature. 426, 540-544 (2003).</li><li>Frank, S., Poncharal, P., Wang, Z. L., de Heer, W. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+Nanotube+Quantum+Resistors.">Carbon Nanotube Quantum Resistors.</a> Science. 280, 1744-1746 (1998).</li><li>Bastard, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superlattice+band+structure+in+the+envelope-function+approximation.">Superlattice band structure in the envelope-function approximation.</a> Phys Rev B. 24, 5693-5697 (1981).</li><li>Sloan, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+One-Dimensional+BaI2+Chain+with+Five-+and+Six-Coordination,+Formed+within+a+Single-Walled+Carbon+Nanotube.">A One-Dimensional BaI2 Chain with Five- and Six-Coordination, Formed within a Single-Walled Carbon Nanotube.</a> Angew Chem I E. 41, 1156-1159 (2002).</li><li>Philp, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+encapsulated+helical+one-dimensional+cobalt+iodide+nanostructure.">An encapsulated helical one-dimensional cobalt iodide nanostructure.</a> Nat Mater. 2, 788-791 (2003).</li><li>Carter, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlation+of+Structural+and+Electronic+Properties+in+a+New+Low-Dimensional+Form+of+Mercury+Telluride.">Correlation of Structural and Electronic Properties in a New Low-Dimensional Form of Mercury Telluride.</a> Phys Rev Lett. 96, 215501 (2006).</li><li>Sloan, J., Kirkland, A. I., Hutchison, J. L., Green, M. L. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integral+atomic+layer+architectures+of+1D+crystals+inserted+into+single+walled+carbon+nanotubes.">Integral atomic layer architectures of 1D crystals inserted into single walled carbon nanotubes.</a> Chem Commun. , 1319-1332 (2002).</li><li>Eliseev, A., Yashina, L., Kharlamova, M., Kiselev, N., Marulanda, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electronic Properties of Carbon Nanotubes. , (2013).</li><li>Senga, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+structure+and+dynamic+behaviour+of+truly+one-dimensional+ionic+chains+inside+carbon+nanotubes.">Atomic structure and dynamic behaviour of truly one-dimensional ionic chains inside carbon nanotubes.</a> Nat Mater. 13, 1050-1054 (2014).</li><li>Spencer, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raman+Spectroscopy+of+Optical+Transitions+and+Vibrational+Energies+of+~1+nm+HgTe+Extreme+Nanowires+within+Single+Walled+Carbon+Nanotubes.">Raman Spectroscopy of Optical Transitions and Vibrational Energies of ~1 nm HgTe Extreme Nanowires within Single Walled Carbon Nanotubes.</a> ACS Nano. 8, 9044-9052 (2014).</li><li>Brown, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+yield+incorporation+and+washing+properties+of+halides+incorporated+into+single+walled+carbon+nanotubes.">High yield incorporation and washing properties of halides incorporated into single walled carbon nanotubes.</a> Appl Phys A. 76, 457-462 (2003).</li><li>Ebbesen, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wetting,+filling+and+decorating+carbon+nanotubes.">Wetting, filling and decorating carbon nanotubes.</a> J Phys Chem Solids. 57, 951-955 (1996).</li><li>Cardona, M., Merlin, R., Cardona, M., Merlin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light+Scattering+in+Solid+IX.">Light Scattering in Solid IX.</a> Vol. 108 Top Appl Phys. , 1-14 (2007).</li><li>Schadler, L. S., Giannaris, S. C., Ajayan, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Load+transfer+in+carbon+nanotube+epoxy+composites.">Load transfer in carbon nanotube epoxy composites.</a> Appl Phys Lett. 73, 3842-3844 (1998).</li><li>Zardo, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+Tuning+of+the+Optical+Properties+of+GaAs+Nanowires.">Pressure Tuning of the Optical Properties of GaAs Nanowires.</a> ACS Nano. 6, 3284-3291 (2012).</li><li>Eliseev, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+electronic+properties+of+AgX+(X=Cl,Br,I)-intercalated+single-walled+carbon+nanotubes.">Structure and electronic properties of AgX (X=Cl,Br,I)-intercalated single-walled carbon nanotubes.</a> Carbon. 48, 2708-2721 (2010).</li><li>Dresselhaus, M. S., Dresselhaus, G., Saito, R., Jorio, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raman+spectroscopy+of+carbon+nanotubes.">Raman spectroscopy of carbon nanotubes.</a> Phys Rep. 409, 47-99 (2005).</li><li>Strano, M. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electronic+Structure+Control+of+Single-Walled+Carbon+Nanotube+Functionalization.">Electronic Structure Control of Single-Walled Carbon Nanotube Functionalization.</a> Science. 301, 1519-1522 (2003).</li><li>Weisman, R. B., Bachilo, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dependence+of+Optical+Transition+Energies+on+Structure+for+Single-Walled+Carbon+Nanotubes+in+Aqueous+Suspension:+An+Empirical+Kataura+Plot.">Dependence of Optical Transition Energies on Structure for Single-Walled Carbon Nanotubes in Aqueous Suspension: An Empirical Kataura Plot.</a> Nano Lett. 3, 1235-1238 (2003).</li><li>Blancon, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+measurement+of+the+absolute+absorption+spectrum+of+individual+semiconducting+single-wall+carbon+nanotubes.">Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes.</a> Nat Comms. 4, 2542 (2013).</li><li>Kim, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared-Active+Vibrational+Modes+of+Single-Walled+Carbon+Nanotubes.">Infrared-Active Vibrational Modes of Single-Walled Carbon Nanotubes.</a> Phys Rev Lett. 95, (2005).</li><li>Krestinin, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perspectives+of+Single-Wall+Carbon+Nano-tube+Production+in+the+Arc+Discharge+Process.">Perspectives of Single-Wall Carbon Nano-tube Production in the Arc Discharge Process.</a> Eurasian Chem Technol. 1, 7-18 (2003).</li><li>Pennycook, S. J., Williams, D. B., Carter, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Transmission Electron Microscopy: A Textbook for Materials Science, Second Edition. , (2009).</li><li>Bell, D. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+and+analysis+of+nanowires.">Imaging and analysis of nanowires.</a> Microsc Res Tecnhiq. 64, 373-389 (2004).</li><li>Williams, D., Carter, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Transmission Electron Microscopy. , 581-603 (2009).</li><li>Ingale, A., Bansal, M., Roy, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resonance+Raman+scattering+in+HgTe:+TO-phonon+and+forbidden-LO-phonon+cross+section+near+the+E1+gap.">Resonance Raman scattering in HgTe: TO-phonon and forbidden-LO-phonon cross section near the E1 gap.</a> Phys Rev B. 40, 12353-12358 (1989).</li><li>Shen, Y., Quirke, N., Zerulla, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polarisation+dependence+of+the+squash+mode+in+the+extreme+low+frequency+vibrational+region+of+single+walled+carbon+nanotubes.">Polarisation dependence of the squash mode in the extreme low frequency vibrational region of single walled carbon nanotubes.</a> Appl Phys Lett. 106, 201902 (2015).</li><li>Puretzky, A. A., Geohegan, D. B., Rouleau, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Narrow+and+intense+resonances+in+the+low-frequency+region+of+surface-enhanced+Raman+spectra+of+single-wall+carbon+nanotubes.">Narrow and intense resonances in the low-frequency region of surface-enhanced Raman spectra of single-wall carbon nanotubes.</a> Phys Rev B. 82, 1-9 (2010).</li><li>Yariv, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+application+of+time+evolution+operators+and+Feynman+diagrams+to+nonlinear+optics.">The application of time evolution operators and Feynman diagrams to nonlinear optics.</a> Quantum Electronics, IEEE. 13, 943-950 (1977).</li><li>Cantarero, A., Trallero-Giner, C., Cardona, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excitons+in+one-phonon+resonant+Raman+scattering:+Frohlich+and+interference+effects.">Excitons in one-phonon resonant Raman scattering: Frohlich and interference effects.</a> Phys Rev B. 40, 12290-12295 (1989).</li><li>Shields, A. J., Cardona, M., N&#246;tzel, R., Ploog, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+the+exciton+lifetime+on+resonant+Raman+scattering+in+quantum+wells.">Influence of the exciton lifetime on resonant Raman scattering in quantum wells.</a> Phys Rev B. 46, 10490-10493 (1992).</li><li>Ye, J. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid-gated+interface+superconductivity+on+an+atomically+flat+film.">Liquid-gated interface superconductivity on an atomically flat film.</a> Nat Mater. 9, 125-128 (2010).</li></ol>

The authors have nothing to disclose.

Enquanto uma enorme quantidade de pesquisa tem sido feita sobre nanofios o limite fundamental do menor diâmetro nanofios possíveis nanofios, extremo, dificilmente tem sido explorado. Foi já demonstrado que as propriedades destes nanofios não formam um continuum com nanofios mesmo diâmetro ligeiramente maior, por exemplo eles podem exibir completamente novas formas cristalinas dos seus materiais de origem. Considerando o grande número de possíveis materiais de origem e que cada um dos pais pode produzir muito mais do que um extremo nanofio a gama de possíveis nanofios física é enorme. O facto de a investigação nanofio extrema ainda está em seus estágios iniciais não é porque os métodos de produzi-los não estão bem estabelecidos. O processo de infiltração de fusão previsto no presente artigo é confiável e tem sido usado por muitos grupos e outras abordagens, tais como o enchimento de sublimação estão disponíveis se a infiltração de fusão não é o ideal para qualquer enchimento particular. Em parte, ocampo é retido pela falta de um método relativamente simples e amplamente aplicável para não-destrutiva caracterizando nanofios extremas. Se o campo de nanotubos de carbono é qualquer guia, espectroscopia Raman tem uma boa chance de ser o método de escolha para resolver este problema. A chave para a obtenção de espectros Raman úteis sobre nanofios extremas é reconhecer que em comum com todos os outros sistemas 1D realce de ressonância do espalhamento Raman é uma condição necessária para a observação de qualquer dispersão. Uma vez que o comportamento de ressonância cheia de um tipo de amostra particular foi determinada utilizando os métodos estabelecidos no presente protocolo, é possível usar uma energia de excitação ressonante fixada para a maioria das aplicações de Raman para caracterizar a amostra que irá acelerar as medidas e reduzir o custo do sistema Raman necessária. Como mostrado nos resultados apresentados neste trabalho o problema crítico na obtenção de alta qualidade resultados Resonance Raman em nanofios extremos é oprecisa de ser capaz de realinhar reprodutivelmente o feixe de um laser sintonizável ao longo de vários dias, com elevada precisão. Isto requer modificações específicas para o sistema experimental e a atenção para os detalhes mais importantes da experiência; focagem correcta do sistema óptico, o alinhamento exacto do feixe de laser sobre o objectivo microscópio e a capacidade de corrigir precisamente para qualquer movimento lateral da amostra. As técnicas desenvolvidas para alcançar este formulário a base deste trabalho. Outros têm desenvolvido técnicas e sistemas para melhorar a reprodutibilidade das experiências de ressonância de Raman, incluindo pioneiros, tais como M. Cardona que aplicou a técnica para uma ampla gama de sistemas de massa e assim quântico. Nossa técnica também se baseia no trabalho dos pioneiros da Raman em nanotubos de carbono, incluindo M. Dresselhaus 21. No entanto, o protocolo aqui apresentado é particularmente adequado para as experiências de Ressonância de Raman sobre nanofios extremas. Uma parte fundamental dos success do protocolo foi o desenvolvimento do sistema experimental mostrado na Figura 10. A figura demonstra uma vista em planta da configuração óptica utilizada para as experiências de Raman detalhadas no protocolo. A luz laser é focada através de uma objectiva 50X (marcado OB) sobre a amostra, selado no criostato de acordo com o protocolo. Este criostato é montado em um palco XYZ para permitir que 3 movimento dimensional da amostra para fins de reposicionamento e focalização. A luz do laser é gerado por A e B (sendo uma fonte de bomba e Ti: safira, respectivamente), detalhes exatos do que o laser seja inscrita na ficha de materiais fornecidos. Ao utilizar o filtro de linha de laser comercial (componente C) de luz laser é dirigido através do centro da íris 1 e 2 e colimado utilizando lente 1 e 2 (L1 e L2). A luz passa através de uma placa de meia onda e polarizador (HWP1 e Pol1) para controlar plano de polarização e de laser incidente poder sobre PM2, conforme detalhado no protocolo. A luz do laser é passadoatravés do filtro sintonizável, C, e o uso de espelhos M1 e M2, dirigido para o caminho óptico correcto de tal modo que é normal à face traseira do objectivo (OB) e centrada nas câmaras C1 e C2. O filtro ND é usado para posicionar o feixe reflectido para trás em relação ao objectivo em medidor de energia, PM1, para permitir que o processo de focagem (passo 9.9), a serem executadas. luz de volta espalhados a partir da amostra é recolhida e passada através da lente 3 (L3) e Slit 1 no espectrómetro. Ajustar a largura da fenda e a posição da lente é importante para maximizar o sinal de Raman, como detalhado na secção de protocolo 8. Se o comprimento de onda do laser está fora da linha de laser filtra gama operacional, a configuração de Bragg volume precisa a ser empregue de acordo com a secção 8.2 .1-8.2.3. É importante que o conjunto óptico é alterada para cima de acordo com a linha a tracejado preto conforme a Figura 10, e o espelho M3 é removido a partir do caminho. Finalmente, se realizar experiências dependentes de polarização, é importantecontrolar a polarização e manter a polarização entrar no espectrômetro, isso é explicado na seção 12 do protocolo e componentes a serem adicionados à configuração são realçadas por uma linha tracejada roxo na Figura 10. A linha tracejada azul na Figura 10 indicam componentes que são adicionada para permitir imagens ao vivo da amostra, como indicado pela secção 14 do protocolo. Tal como acontece com todos os métodos experimentais Resonant espalhamento Raman tem suas limitações. Em particular, as fontes de laser sintonizável disponíveis e detectores significa que é muito mais fácil de executar na espectral gama 350-1,000 nm, embora extensão ainda mais no infravermelho e UV são possíveis. O sistema experimental obrigados a assumir espalhamento Raman com fontes ajustáveis ​​não é barato com uma estimativa razoável sendo £ 200-300k no momento da publicação. Além disso, a complexidade dos sistemas necessários significa que eles requerem uma certa familiaridade com ópticoespectroscopia de operar com sucesso. No entanto espalhamento Raman fornece uma combinação de informações que é difícil de obter de outras técnicas. Notavelmente, é possível obter espalhamento Raman, e as energias vibracionais assim, a partir de nanotubos de carbono de parede individuais que ainda não podem ser alcançados por qualquer outra técnica. Agora que as ressonâncias de nanofios estão começando a ser determinada esta abre um leque de possíveis extensões de espalhamento Raman. Em nossa opinião a extensão para eletroquimicamente fechado nanofios extremas 20 em temperaturas abaixo de 4 K 36, permitindo medições em nanofios sobre uma ampla gama de densidades de carga será a chave para a compreensão destes materiais. Finalmente usando espalhamento Raman para a compreensão de transições estruturais e fusão de nanofios extremas pode ajudar a otimizar a qualidade das amostras que podem ser produzidos ainda mais.

Espectroscopia Raman e espectroscopia Raman são técnicas bem estabelecidas que são amplamente exploradas cientificamente e tecnologicamente. Embora primeiro relatado por si mesmo de Raman de 1928 um a chave para o uso generalizado de espectroscopia Raman foi o desenvolvimento de lasers, lasers sintonizáveis, no caso de ressonância de Raman, para proporcionar uma elevada intensidade, as fontes de largura de banda de excitação estreitas. Este documento define por Ressonância espalhamento Raman é um método particularmente importante para investigar a física fundamental e caracterização de amostras de sistemas 1D em nanofios gerais e extremos, por exemplo nanofios com diâmetros de ~ 1-5 átomos. Ele também discute dificuldades particulares para espectroscopia Raman desses nanofios e um protocolo que permite que estes sejam superados e, assim, alcançar medições de alta repetibilidade da dependência energética do laser do espalhamento Raman eficiência nestes sistemas. Existe uma vasta gama de extended, sistemas cristalinos 1D quântica, também conhecidos como nanofios, disponíveis para estudo e aplicação. Estes incluem nanofios de vapor de líquidos sólido crescida semicondutores 2, nanofios lithographically definidos 3, alumina anódica e acompanhar membrana etch modelo nanofios 4 e outros. Uma das principais razões para o interesse nestes sistemas é que eles combinam grandes efeitos de confinamento quântico com a capacidade de elétrons e outras excitações mover-se livremente ao longo da estrutura. Em alguns aspectos, os nanofios são bastante diferente do seu material de origem, por exemplo, redução de triagem eletromagnético devido a cargas livres 5, e em alguns casos reduzida espalhamento de elétrons levando a transporte balístico 6. No entanto, em muitos aspectos, os nanofios ainda estão a granel, como, por exemplo, a estrutura de ligação e de cristal local, e quase sempre a qualidade fundamental das funções de onda eletrônicos em escala atômica são apenas fracamente modificado em relação com massa paraque o envelope aproximação 7 é válida. No entanto, como as dimensões das instruções são confinados reduzida para alguns átomos, nanofios com inteiramente nova ligação pode ocorrer formação de formas alotrópicas nunca vistos anteriormente 8-10. Esses nanofios são extremas em dois sentidos; eles estão no limite extremo da possível redução na secção transversal 11-13 e eles têm propriedades extremas 10,13,14. Antes de empreender espectroscopia Raman, é necessário para produzir as amostras de nanofios extremas. A metodologia estabelecida neste artigo para gerar esses nanofios é a infiltração de fusão de materiais em nanotubos de carbono de parede. Derreter a infiltração é um dos protocolos de enchimento dois de alto rendimento utilizadas para a obtenção de nanotubos continuamente cheios de parede única de carbono (SWNT), sendo o outro de sublimação, que é popular para a introdução de moléculas (isto é, fulerenos) e alguns sais binários, mais recentemente Csl 13. Enquanto o último método produz perto enchimento quantitativa, é limitado pelo facto de o material a ser introduzido deve prontamente sublime que restringe grandemente o número e tipo de recheios que podem ser introduzidas em SWNT. O protocolo de fusão pode infiltração de enchimento, com cuidado, ser usadas para produzir perto quantitativa de enchimento 15 e tem menos restrições do que a do protocolo de sublimação. Estes são de que o material deve ter uma tensão superficial inferior a 100-200 mN m -1 e uma temperatura de fusão abaixo de cerca de 1300 K para evitar danificar os nanotubos de carbono central 16. A microscopia electrónica de transmissão (MET) é o melhor método para caracterizar a qualidade do enchimento dos nanotubos de carbono e identificar a estrutura cristalina ou estruturas dos nanofios extremas produzidos. Resolvendo estruturas de fragmentos de cristal incorporado-SWNT a partir de imagens HRTEM envolve comparações de tentativa e erro entre simulações de imagem de julgamento fragmento de cristal models e o contraste da imagem obtida experimentalmente. Este documento descreve um protocolo para confirmar a microestrutura dos motivos de nanofios extremas em amostras SWNT por simulação imagem HRTEM como um prelúdio para a sua caracterização espectroscópica. Espectroscopia Raman 17 é uma ferramenta ideal, tanto para a compreensão da física fundamentais de nanofios extremas e, uma vez que as energias de ressonância tiverem sido determinados, para caracterizar o tipo e a qualidade das amostras de nanofios. Fundamentalmente, Resonance Raman permite a determinação direta de ambas as energias de excitação óptica e vibracionais 17. Com modelagem adicional da dependência energética de fótons da ressonância é possível quantificar a interação elétron-fônon 17. Uma vez que as energias de ressonância foram determinados para determinadas nanofios extremas, o espectro de Raman dos nanofios pode ser usado para controlar a tensão 18 e 19 muda de fase estrutural devidotemperatura, pressão hidrostática, ou flexão do fio. Enquanto ainda a ser comprovada, é provável que em alguns nanofios extremas magnéticos girar excitações levará a dispersão de Raman que lhes permite ser sondada. Extensão do espalhamento Raman de amostras mantidas em uma célula espectroeletroquímica pode ser usado para sondar transferência de carga entre os nanofios e nanotubos de extremos de acolhimento 20. Como uma ferramenta de caracterização espectroscopia Raman proporciona um método para o não-contacto, a determinação não destrutiva do tipo e qualidade nanofio 21. Ele pode ser usado como uma ferramenta para a caracterização de amostras após a produção e / ou purificação e mesmo quando os nanofios foram incluídos em dispositivos tais como transistores ou compósitos que são pelo menos parcialmente transparente, em que as energias necessárias fotões. Não há uma técnica que pode fornecer uma alternativa directa para Ressonância espalhamento Raman (RRS); no entanto, há uma série de outras técnicas que se sobrepõem alguns aspects das capacidades deste método. Em termos de determinação das energias de transição ópticas de nanofios extremas UV-VIS-NIR medições de absorção 22 oferecem uma técnica muito mais simples. No entanto, em amostras com um conjunto diferente de estruturas espectroscopia de absorção não é possível separar as diferentes características ópticas em conjuntos associados com estruturas particulares. Ressonância espalhamento Raman pode conseguir isso devido à associação de espectros ópticos e vibracional. Uma combinação das duas técnicas em que um de UV-VIS-NIR destaques medição de absorção alvo energias de ressonância de Raman pode acelerar consideravelmente o processo global. Espectroscopia de fotoluminescência de excitação (PLE) 23 não oferecem a capacidade de associar diferentes transições ópticas em uma única amostra; no entanto, ele só funciona para alguns, particularmente nanofios não-metálicos, e é apenas um pouco menos complicada de realizar do que RRS e em geral requer amostras monodispersas protegidos do environment para ser completamente bem sucedida. Ao contrário de PLE, espectroscopia Raman funciona igualmente bem com empacotados e amostras monodispersas e, portanto, requer preparação da amostra pouco. Enquanto ainda pouco utilizado, espectroscopia de espalhamento Rayleigh no nanofios individuais 24, seguido de Microscópio Electrónico de Transmissão (TEM) análise da estrutura do nanofio pode identificar todas as energias excitação óptica do fio na gama espectral investigada e identificar uma estrutura nanofio nomeadamente . No entanto, esta técnica não fornece a informação de energia vibracional possível com RRS; é muito difícil de executar e nunca vai ser adequado como uma ferramenta geral caracterização. Em termos de informação de energia vibracional a única alternativa viável atualmente é a espectroscopia IR 25 no entanto, isso é provável, devido às regras de selecção, para sondar um conjunto diferente de energias vibracionais e, assim, ser complementares e não competitivos. Além disso IR spectroscopy vai sofrer dos mesmos problemas com amostras do conjunto como medidas de absorção UV-VIS-NIR. Como já foi discutido espectroscopia Raman foi aplicado a uma ampla gama de problemas no âmbito da ciência. Em sistemas moleculares que é usado para complementar a espectroscopia de IV para a determinação espectros vibracionais e também como uma técnica de impressão digital para analisar a composição dos materiais. Tem sido amplamente explorados em sistemas cristalinos, por exemplo, a dispersão de luz na série de livros de sólidos inclui nove volumes. No caso de sistemas 3D e 2D, excitação ressonante é usado menos para aumentar a intensidade total dispersão e mais para melhorar a contribuição das transições ópticas específicas dentro do processo Raman levando à quebra das regras de seleção padrão e a capacidade de quantificar a interação das excitações observadas no espectro de Raman com estados electrónicos específicos. Mais recentemente espectroscopia Raman tem sido central to estudo de nanotubos de carbono, particularmente nanotubos de carbono de parede. A pesquisa de nanotubos de carbono 21 destacou o fato de que para os sistemas 1D excitação ressonante não é opcional, como é para a maioria das aplicações de Raman para sistemas 3D e 3D, mas é estritamente necessário. Isto é porque não-ressonante Raman é fraco demais para ser observado e é só quando a excitação é ressonante com as fortes singularidades Van Hove na densidade óptica de estados, que são uma característica dos sistemas de 1D, em particular, que qualquer espectro de Raman pode ser observada. Assim, no caso de nanofios extremas a utilização de espectroscopia de Raman requer uma medição completa ressonância de Raman para encontrar as ressonâncias de todas as nanofios de uma amostra antes de espectroscopia Raman pode ser aplicado para estudar estes materiais.

<table>
	<tbody>
		<tr>
			<td>Carbon Nanotubes</td>
			<td>Nanointegris</td>
			<td>NI96</td>
			<td></td>
		</tr>
		<tr>
			<td>Carbon Nanotubes</td>
			<td>Private</td>
			<td></td>
			<td>Synthesis described in Eurasian Chem.-Technol. J. 2005, 5, 7-18.</td>
		</tr>
		<tr>
			<td>Mercury Telluride</td>
			<td>VMR</td>
			<td></td>
			<td>99.999% metals basis</td>
		</tr>
		<tr>
			<td>Silica Quartz Tubing</td>
			<td>H. Baumbach &#38; Co.&#160;</td>
			<td></td>
			<td>Various diameters and lengths used - typically 1 cm OD, 0.8 cm ID and 8cm long.&#160;</td>
		</tr>
		<tr>
			<td>Tube furnace</td>
			<td>Carbolite</td>
			<td>&#160;MTF-12/38/250</td>
			<td></td>
		</tr>
		<tr>
			<td>JEOL ARM 200F&#160;</td>
			<td>JEOL&#160;</td>
			<td></td>
			<td>200 kV High Resolution TEM Operated at 80 kV and equipped with&#160;</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>CEOS hardware spherical aberation (Cs) imaging corrector. Cs corrected&#160;</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>to 0.001 mm.</td>
		</tr>
		<tr>
			<td>SC1000 ORIUS camera</td>
			<td>Gatan</td>
			<td></td>
			<td>Size of CCD 4008 x 2672</td>
		</tr>
		<tr>
			<td>Digital Micrograph Suite 2.31</td>
			<td>Gatan</td>
			<td></td>
			<td>64 bit version</td>
		</tr>
		<tr>
			<td>XMax X-ray Microanalysis&#160;</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td>This detector uses the silicon drift detection (SDD) principle. 1 nm diameter electron probe.</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Crystalmaker Ver 8.7</td>
			<td>Crystalmaker</td>
			<td></td>
			<td>Used for assembling crystal fragments for image simulations</td>
		</tr>
		<tr>
			<td>Nanotube Modeler</td>
			<td colspan="2">JCrystalSoft &#169;2015-2015</td>
			<td>Used for generating Nanotube models</td>
		</tr>
		<tr>
			<td>SimulaTEM</td>
			<td>Private</td>
			<td></td>
			<td>Ultramicroscopy, 2010, 110, 95-104.</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Verdi V8 Pump</td>
			<td>Coherent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mira 900 Ti:Sapphire</td>
			<td>Coherent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Volume Bragg Grating</td>
			<td>Optigrate</td>
			<td></td>
			<td>Specfication between 680-720nm</td>
		</tr>
		<tr>
			<td>Photonetc TLS 850 LLTF&#160;</td>
			<td>Photonetc</td>
			<td></td>
			<td>Tunable between 700-1000nm</td>
		</tr>
		<tr>
			<td>LMPLAN IR50x MircoscopeObjective</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Triple Raman Spectrometers</td>
			<td>Princeton Instruments</td>
			<td></td>
			<td>triple 600nm using gratings 900, 900, 1800 lines/mm</td>
		</tr>
		<tr>
			<td>CCD</td>
			<td>Princeton Instruments</td>
			<td></td>
			<td>deep depleted, UV enchanced liquid N2 Cooled Silicon CCD</td>
		</tr>
	</tbody>
</table>

resonance raman spectroscopy of extreme nanowires and other 1d systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

Watch this Scientific Journal Video about Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems at JoVE.com

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

Espectroscopia Raman de nanofios extremos e Outros Sistemas 1D

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

resonance-raman-spectroscopy-of-extreme-nanowires-and-other-1d-systems

Research

JoVE Journal

Engineering

15.0K visualizações.  University of Southampton. The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

Vídeo: Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

Síntese e microdiffraction a pressões e temperaturas extremas

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

Engenharia

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

Ultra Density Array of alinhados verticalmente Nanofios orgânicos pequeno-moleculares sobre substratos Arbitrárias

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Avaliando plasmônicos Transporte em Prata atual de transporte de nanofios

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 &#181;m were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min&#160;of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution.

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Procedures are outlined to prepare segmented and coaxial nanowires via templated electrodeposition in nanopores. As examples, segmented nanowires consisting of Ag and ZnO segments, and coaxial nanowires consisting of a TiO2 shell and a Ag core were made. The nanowires were used in photocatalytic hydrogen formation experiments.

Preparação e Utilização de fotocataliticamente atividade segmentada Ag | ZnO e Coaxial TiO<sub&gt; 2</sub&gt;-AG nanofios feitos por Templated Electrodeposition

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and ...

High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe.

Nuclear magnetic resonance is one of the most important spectroscopic tools. Here, the development of a new approach under high pressure, currently up to 10.1 GPa, is presented. This opens a new window into condensed matter physics and chemistry, where high-pressure research is of great importance.

Alta Sensibilidade de Ressonância Magnética Nuclear em Giga-Pascal Pressões: uma nova ferramenta para sondar propriedades eletrônicas e químicas da Matéria Condensada sob condições extremas

Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their ...

Surface Enhanced Raman Spectroscopy Detection of Biomolecules Using EBL Fabricated Nanostructured Substrates

Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules is reported. The entire sequence of relevant experimental steps is described, involving the fabrication of nanostructured substrates using electron beam lithography, immobilization of biomolecules on the substrates, and their characterization utilizing surface-enhanced Raman spectroscopy (SERS). Three different designs of nano-biological systems are employed, including protein A, glucose binding protein, and a dopamine binding DNA aptamer. In the latter two cases, the binding of respective ligands, D-glucose and dopamine, is also included. The three kinds of biomolecules are immobilized on nanostructured substrates by different methods, and the results of SERS imaging are reported. The capabilities of SERS to detect vibrational modes from surface-immobilized proteins, as well as to capture the protein-ligand and aptamer-ligand binding are demonstrated. The results also illustrate the influence of the surface nanostructure geometry, biomolecules immobilization strategy, Raman activity of the molecules and presence or absence of the ligand binding on the SERS spectra acquired.

We describe the fabrication and characterization of nano-biological systems interfacing nanostructured substrates with immobilized proteins and aptamers. The relevant experimental steps involving lithographic fabrication of nanostructured substrates, bio-functionalization, and surface-enhanced Raman spectroscopy (SERS) characterization, are reported. SERS detection of surface-immobilized proteins, and probing of protein-ligand and aptamer-ligand binding is demonstrated.

Superfície reforçada Raman Detection Espectroscopia de Biomoléculas Usando EBL Fabricadas Nanoestruturados Substratos

Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules ...

Characterization of Nanocrystal Size Distribution using Raman Spectroscopy with a Multi-particle Phonon Confinement Model

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The common techniques used for the size analysis are transmission electron microscopy (TEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). These techniques, however, are not suitable for analyzing the nanocrystal size distribution in a fast, non-destructive and a reliable manner at the same time. Our aim in this work is to demonstrate that size distribution of semiconductor nanocrystals that are subject to size-dependent phonon confinement effects, can be quantitatively estimated in a non-destructive, fast and reliable manner using Raman spectroscopy. Moreover, mixed size distributions can be separately probed, and their respective volumetric ratios can be estimated using this technique. In order to analyze the size distribution, we have formulized an analytical expression of one-particle PCM and projected it onto a generic distribution function that will represent the size distribution of analyzed nanocrystal. As a model experiment, we have analyzed the size distribution of free-standing silicon nanocrystals (Si-NCs) with multi-modal size distributions. The estimated size distributions are in excellent agreement with TEM and PL results, revealing the reliability of our model.

We demonstrate how to determine the size distribution of semiconductor nanocrystals in a quantitative manner using Raman spectroscopy employing an analytically defined multi-particle phonon confinement model. Results obtained are in excellent agreement with the other size analysis techniques like transmission electron microscopy and photoluminescence spectroscopy.

Caracterização de nanocristal Tamanho Distribution utilizando Espectroscopia Raman com um Multi-partícula Phonon Confinamento Modelo

Analysis of the size distribution of nanocrystals is a critical requirement for the processing and optimization of their size-dependent properties. The ...

A Fabrication Method for Highly Stretchable Conductors with Silver Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of stretchable electronic devices is the preparation of stretchable conductors with great mechanical stability. In this study, we developed a simple fabrication method to chemically solder the contact points between silver nanowire (AgNW) networks. AgNW nanomesh was first deposited on a glass slide via spray coating method. A reactive ink composed of silver nanoparticle (AgNPs) precursors was applied over the spray coated AgNW thin films. After heating for 40 min, AgNPs were preferentially generated over the nanowire junctions to solder the AgNW nanomesh, and reinforced the conducting network. The chemically modified AgNW thin film was then transferred to polyurethane (PU) substrates by casting method. The soldered AgNW thin films on PU exhibited no obvious change in electrical conductivity under stretching or rolling process with elongation strains up to 120%.

A simple synthesis method is used to chemically solder silver nanowire thin film to fabricate highly stretchable and conductive metal conductors.

Um método de fabricação para Condutores altamente extensível com prata Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of ...

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we demonstrate an optical spectroscopy method that is capable of resolving spectral features beyond that of the spin fine structure and homogeneous linewidth of single quantum dots (QDs) using a standard, easy-to-use spectrometer setup. This method incorporates both laser and photoluminescence spectroscopy, combining the advantage of laser line-width limited resolution with multi-channel photoluminescence detection. Such a scheme allows for considerable improvement of resolution over that of a common single-stage spectrometer. The method uses phonons to assist in the measurement of the photoluminescence of a single quantum dot after resonant excitation of its ground state transition. The phonon&#39;s energy difference allows one to separate and filter out the laser light exciting the quantum dot. An advantageous feature of this method is its straight forward integration into standard spectroscopy setups, which are accessible to most researchers.

The manuscript describes a method of phonon-assisted quasi-resonant fluorescence spectroscopy that incorporates both laser-limited resolution and photoluminescence (PL) spectroscopy. This method utilizes optical phonons to provide linewidth-limited resolution spectra of atom-like semiconductor structures in the energy domain. The method is also easily realized with a single spectrometer optical spectroscopy setup.

-Ressonância Quasi alta resolução Phonon assistida espectroscopia de fluorescência

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we ...