This work was supported in part by grants-in-aid KAKENHI from the Japan Society for the Promotion of Science (JSPS) and the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) Japan (#26104539, #26620020, #26810011, #15H03766, #15KT0060, #16H00826, and #16K13927); the Konica Minolta Science and Technology Foundation; the "Planting Seeds for Research" program of TokyoTech; the Imaging Science Project of the Center for Novel Science Initiatives (CNSI) at the National Institutes of Natural Sciences (NINS) (#IS261006); the RIKEN-IMS joint program on "Extreme Photonics;" and the Consortium for Photon Science and Technology (CPhoST).

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The authors have nothing to disclose.

Mevcut prosedür yarık tabanlı 2D görüntü ayarı ile moleküler dönme gerçek zamanlı film yakalamak için bize sağlar. gözlenen iyonlar yarık geçtiğinden, adım 1.5 kritik adımlardan biridir. yarık bıçaklarının keskin olmalıdır. Küçük bir kusur olduğunda, bu tür yarık 0,3 mm göçük gibi bir çizik iyon görüntüde (Şekil 6) görülmektedir. Böyle bir durumda, yarık bıçak 2.000 grit ıslak zımpara kağıdı ile parlatılmış olmalıdır. A...

daha derin bir anlayış ve moleküllerin dinamik doğasının daha iyi kullanmak için, açıkça ilgi moleküler hareketlerini görselleştirmek için esastır. Zamana bağımlı Coulomb patlama görüntüleme bu hedefe 1, 2, 3 ulaşmak için güçlü yaklaşımlardan biridir. Bu yaklaşımda, ilgilenilen moleküler dinamik pompa ultra lazer alanı tarafından başlatılan ve daha sonra, bir zaman gecikmeli prob sinyali ile sondalandı. Sonda ışınlama üzerine, moleküller çarpın iyonize ve Coulomb itme nedeniyle fragman iyonları ayrılır. püskürtülen iyon alansal dağılımı prob ışınlama moleküler yapısı ve uzaysal bir ölçüsüdür. pompa-sonda gecikme süresini tarayarak ölçüm dizisi moleküler film yaratılmasına yol açar. Bu dikkat çekicidir ki en basit durumda - iki atomlu moleküller - püskürtülen iyonların açısal dağılımıdoğrudan moleküler eksen dağılımı (yani, kare dönme dalga fonksiyonu) yansıtır. Pompa işlemi ile ilgili olarak, ultra lazer alanları kullanılarak moleküler hareket tutarlı kontrol son ilerleme yüksek kontrollü döner dalga paketleri 4 oluşturulması, 5 yol açmıştır. Bundan başka, dönme yönü aktif bir kutuplaşma-kontrollü lazer alanı 6, 7, 8 ile kontrol edilebilir. Nedenle, Coulomb patlama görüntüleme tekniği, örneğin pompa işlemi 9, 10, 11, 12, 13 ile birleştirildiğinde dalgalı doğa dahil olmak üzere moleküler rotasyon detaylı bir resmini, görünene beklenmektedir edilmiştir. Ancak, bazıZaman aşağıda belirtildiği gibi, mevcut görüntüleme yöntemleri ile ilgili deneysel zorluklarla karşılaşmaktadırlar. Bu yazının amacı bu zorlukların üstesinden ve moleküler dönme dalga paketleri yüksek kaliteli film yaratma yeni bir yol sunmaktır. Fiziksel etkileri ile birlikte, mevcut yöntem ile çekilen moleküler dönme ilk deneysel film, önceki yazıda 11 sunuldu. gelişme arka plan, mevcut görüntüleme tekniğinin ayrıntılı teorik yönü ve varolan diğer tekniklerle bir karşılaştırma önümüzdeki yazıda verilecektir. Burada, biz esas olarak tipik pompa-sonda optik kurulum kombinasyonu ve yeni görüntüleme cihazları dahil, prosedürün pratik ve teknik yönleri üzerinde durulacak. Bir önceki yazıda olduğu gibi, hedef sistem tek yönlü azot molekülleri 11 dönmektedir. ana deneysel zorlukşematik olarak Şekil 1&#39;de gösterildiği görüntüleme kurulum, mevcut dedektör pozisyonu veya kamera açısı ile bir ilgisi yoktur. Dönme ekseni lazer alanı kaynaklı moleküler rotasyon lazer yayılma ekseni 6, 7, 8 denk için, dönme ekseni boyunca bir dedektör yüklemek için pratik değildir. lazer ışınlama önlemek amacıyla dedektör takıldığında, kamera açısı dönme yan gözlem karşılık gelir. Bu durumda, tahmin edilen (2B) iyonu görüntü 14 moleküllerin orijinal yönünü yeniden imkansızdır. Bir 3D görüntü detektörü 14, 15, 16, 17, 18, 19, en iyi detektör ve iyon IMPAC hangi varış zamanı ilet pozisyonları ölçülebilir, Coulomb patlama görüntüleme 10, 12 kullanılarak doğrudan moleküler rotasyon gözlemlemek için benzersiz bir yol sundu. Ancak, lazer atış başına kabul edilebilir iyon sayıları yüksek görüntü kalitesi 14 ile moleküler hareket uzun bir film oluşturmak zor, yani 3D dedektörü düşük (genellikle &lt;10 iyonları) bulunmaktadır. dedektörleri (genellikle ns) ölü zaman da görüntü çözünürlüğü ve görüntüleme verimini etkiler. Aynı zamanda &lt;~ 1 kHz lazer tekrarlama oranı ile gerçek-zamanlı iyon görüntüsünü izleyerek iyi bir pompa-sonda kiriş örtüşme yapmak için basit bir görev değildir. Çeşitli gruplar 3D tekniği kullanılarak dönme dalga paketleri gözlenen olmasına rağmen, mekansal bilgi sınırlı ve / veya doğrudan, ve karmaşık düğüm yapıları da dahil olmak üzere dalga doğa ayrıntılı görselleştirme, 12, 10 elde değil edildi. özüyeni bir görüntüleme yöntemidir Şekil 1&#39;de &quot;yeni kamera açısı&quot; kullanılmasıdır. 2B detektör dönme ekseni yönünden gözlem yol dönme düzlemine paralel olduğu halde, bu yapılandırmada, bir detektör lazer ışınına maruz kalma önlenir. Yarık bir görüntü katkıda dönme düzlemi sadece iyon (lazer atımlarının polarizasyon düzlemi) sağlar. 3B detektörü daha yüksek bir sayısı oranı (tipik olarak ~ 100 iyonlar) sunan bir 2B detektör, kullanılabilir. Ölçüm verimi yüksek ise elektronik kurulumu, 3D tespiti halinde daha basittir. Zaman alıcı, Abel inversiyon 14 olarak matematiksel rekonstrüksiyon, aynı zamanda açısal bilgileri ayıklamak için gerekli değildir. Bu özellikler, ölçüm sisteminin kolay optimizasyonu ve yüksek kaliteli filmlerin üretilmesini sağlar. Bir standart 2D / 3D yüklü parçacık görüntüleme cihazı kolayca mevcut kurulum witho için değiştirilebilirpahalı ekipman kullanımını ut.

<table><tbody><tr><td>CMOS camera</td><td>Toshiba TELI</td><td>BU-238M-ES</td><td>equipped with SONY IMX174 sensor</td></tr><tr><td>High voltage switch</td><td>Behlke</td><td>HTS-41-03-GSM</td><td></td></tr><tr><td>High voltage switch</td><td>Behlke</td><td>HTS-80-03</td><td></td></tr><tr><td>Digital delay generator</td><td>Stanford research systems</td><td>DG535</td><td></td></tr><tr><td>Digital delay generator</td><td>Stanford research systems</td><td>DG645</td><td></td></tr><tr><td>Microchannel plate</td><td>Photonis</td><td>3075</td><td></td></tr><tr><td>Pulsed valve</td><td>LAMID LTD</td><td>Even-Lavie valve&amp;nbsp;</td><td>High repetition, room temperature model</td></tr><tr><td>Molecular beam skimmers</td><td>Institute for Molecular Science</td><td>13C11</td><td>3 and 1.5 mm center hole, 25 degrees full inner angle, and ~50 mm length</td></tr><tr><td>Optical Comparator</td><td>Nikon</td><td>V-24B</td><td></td></tr><tr><td>DPSS laser</td><td>Lighthouse Photonics</td><td>Sprout</td><td></td></tr><tr><td>Femtosecond Ti:Sapphire oscillator</td><td>KMLabs</td><td>Halcyon</td><td></td></tr><tr><td>Femtosecond Ti:Sapphire amplifier</td><td>Quantronix</td><td>Odin-II HE</td><td></td></tr><tr><td>Motorized linear stage</td><td>Sigma Koki</td><td>KST(GS)-100X</td><td></td></tr><tr><td>Manual X-stage</td><td>Sigma Koki</td><td>TSD-601S</td><td></td></tr><tr><td>High resolution mirror mount</td><td>Newport</td><td>Suprema SX100-F2KN-254</td><td></td></tr><tr><td>High resolution mirror mount</td><td>LIOP-TEC GmbH</td><td>SR100-100R-2-HS</td><td></td></tr><tr><td>Polarization checker</td><td>Paradigm Devices, Inc.</td><td>O-tool VIS</td><td></td></tr><tr><td>Instrument communication interface</td><td>National Instruments</td><td>NI-MAX</td><td></td></tr><tr><td>Graphical development environment for measurement programs</td><td>National Instruments</td><td>LabVIEW 2014</td><td></td></tr><tr><td>Laser line dielectric mirror</td><td>CVI/LEO</td><td>TLM2-400/800-45UNP</td><td></td></tr><tr><td>Laser line dielectric mirror</td><td>Altechna</td><td>Low GDD Ultrafast mirror</td><td></td></tr><tr><td>Laser line dielectric mirror</td><td>Altechna</td><td>Low GDD Ultrafast mirror</td><td></td></tr><tr><td>Femtosecond polarizer</td><td>Advanced Thin Films</td><td>PBS-GVD</td><td></td></tr></tbody></table>

direct imaging of laser-driven ultrafast molecular rotation

Biz lazer kaynaklı, ultra hızlı moleküler dönme dalga paketi dinamiklerini görselleştirmek için bir yöntem mevcut. Biz şimdiye kadar-pratik kamera açısı gerçekleştiği yeni bir 2-boyutlu Coulomb patlama görüntüleme kurulumu geliştirdik. Bizim görüntüleme tekniğinde, iki atomlu moleküller bir dairesel polarize güçlü lazer darbe ile ışınlanmış. atılır atom iyonları lazer yayılımı dik hızlanır. Lazer polarizasyon düzlemi içinde yatmakta olarak iyonlar mekanik yarık kullanılarak seçilir ve yüksek verimlilik ile görüntülenmiş olan, 2-boyutlu bir dedektör polarizasyon düzlemine paralel monte. Bir dairesel polarizasyonlu (izotropik) Coulomb patlama darbe kullanıldığı için, püskürtülen iyonlarının gözlenen açısal dağılımı doğrudan darbe ışınlama zamanında kare dönme dalga fonksiyonuna karşılık gelir. Moleküler dönme gerçek zamanlı bir film oluşturmak için, bu görüntüleme tekniği femtosaniye pompa-sonda O ile birleştirilirptical kurulum hangi pompa darbeleri tek yönlü moleküler toplulukları dönen oluşturun. Nedeniyle bizim algılama sisteminin yüksek görüntü throughput, pompa-sonda deneysel durum kolaylıkla gerçek zamanlı anlık takip edilerek optimize edilebilir. Bunun bir sonucu olarak, gözlemlenen filmin kalitesi hareketinin detaylı dalga doğasını görselleştirmek için yeterince yüksektir. Biz de mevcut teknik kapsamlı değişiklikler için gerek kalmadan moleküler sistemler için yeni bir kamera açısı veya görüş açısını sunan mevcut standart iyon görüntüleme kurulumları uygulanabilir unutmayın.

Şekil 4A bir prob lazer atış için alınan N 2+ sonda ışınlama (Coulomb patlama) üzerine atılır iyon, bir prob-sadece ham görüntü gösterir. Her parlak nokta bir iyon karşılık gelir. Şekil 4B 10.000 çiftlendirildi ham kamera görüntülerinin bir özetlenebilir görüntü gösterir. Bu görüntüler, görüntü ayarları polarizasyon düzleminde tüm oryantasyon açıları molekülleri izleyebilirsiniz göstermektedir. ...

Watch this Scientific Journal Video about Direct Imaging of Laser-driven Ultrafast Molecular Rotation at JoVE.com

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

Lazer güdümlü Ultrafast Moleküler Rotasyon Doğrudan Görüntüleme

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb ...

direct-imaging-of-laser-driven-ultrafast-molecular-rotation

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9.6K Görüntüleme.  Tokyo Institute of Technology. We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

Video: Direct Imaging of Laser-driven Ultrafast Molecular Rotation

Fluorescence Lifetime Imaging of Molecular Rotors in Living Cells

Diffusion is often an important rate-determining step in chemical reactions or biological processes and plays a role in a wide range of intracellular events. Viscosity is one of the key parameters affecting the diffusion of molecules and proteins, and changes in viscosity have been linked to disease and malfunction at the cellular level.1-3 While methods to measure the bulk viscosity are well developed, imaging microviscosity remains a challenge. Viscosity maps of microscopic objects, such as single cells, have until recently been hard to obtain. Mapping viscosity with fluorescence techniques is advantageous because, similar to other optical techniques, it is minimally invasive, non-destructive and can be applied to living cells and tissues.
Fluorescent molecular rotors exhibit fluorescence lifetimes and quantum yields which are a function of the viscosity of their microenvironment.4,5 Intramolecular twisting or rotation leads to non-radiative decay from the excited state back to the ground state. A viscous environment slows this rotation or twisting, restricting access to this non-radiative decay pathway. This leads to an increase in the fluorescence quantum yield and the fluorescence lifetime. Fluorescence Lifetime Imaging (FLIM) of modified hydrophobic BODIPY dyes that act as fluorescent molecular rotors show that the fluorescence lifetime of these probes is a function of the microviscosity of their environment.6-8 A logarithmic plot of the fluorescence lifetime versus the solvent viscosity yields a straight line that obeys the F&ouml;rster Hoffman equation.9 This plot also serves as a calibration graph to convert fluorescence lifetime into viscosity.
Following incubation of living cells with the modified BODIPY fluorescent molecular rotor, a punctate dye distribution is observed in the fluorescence images. The viscosity value obtained in the puncta in live cells is around 100 times higher than that of water and of cellular cytoplasm.6,7 Time-resolved fluorescence anisotropy measurements yield rotational correlation times in agreement with these large microviscosity values. Mapping the fluorescence lifetime is independent of the fluorescence intensity, and thus allows the separation of probe concentration and viscosity effects. 
In summary, we have developed a practical and versatile approach to map the microviscosity in cells based on FLIM of fluorescent molecular rotors.

Fluorescence Lifetime Imaging (FLIM) has emerged as a key technique to image the environment and interaction of specific proteins and dyes in living cells. FLIM of fluorescent molecular rotors allows mapping of viscosity in living cells.

Yaşayan Hücreler Moleküler Rotorlar arasında Flüoresans Ömrü Görüntüleme

Diffusion is often an important rate-determining step in chemical reactions or biological processes and plays a role in a wide range of intracellular ...

Biyomühendislik

Spatial Separation of Molecular Conformers and Clusters

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.

We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.

Moleküler Konformatörlerin ve Kümelerin Mekansal Ayrımı

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold ...

Mühendislik

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is &#177; 5 parts in 107. Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH2F2, was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO2 pump laser, and strength.

We describe the generation of far-infrared radiation using an optically pumped molecular laser along with the measurement of their frequencies with heterodyne techniques. The experimental system and techniques are demonstrated using difluoromethane (CH2F2) as the laser medium whose results include three new laser emissions and eight measured laser frequencies.

Uzak-kızılötesi lazer Emisyonları ve Bunların Frekansları ölçülmesi Karakterizasyonu

The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and ...

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

This article shows how the COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) or the "reaction microscope" technique can be used to distinguish between enantiomers (stereoisomers) of simple chiral species on the level of individual molecules. In this approach, a gaseous molecular jet of the sample expands into a vacuum chamber and intersects with femtosecond (fs) laser pulses. The high intensity of the pulses leads to fast multiple ionization, igniting a so-called Coulomb Explosion that produces several cationic (positively charged) fragments. An electrostatic field guides these cations onto time- and position-sensitive detectors. Similar to a time-of-flight mass spectrometer, the arrival time of each ion yields information on its mass. As a surplus, the electrostatic field is adjusted in a way that the emission direction and the kinetic energy after fragmentation lead to variations in the time-of-flight and in the impact position on the detector.
Each ion impact creates an electronic signal in the detector; this signal is treated by high-frequency electronics and recorded event by event by a computer. The registered data correspond to the impact times and positions. With these data, the energy and the emission direction of each fragment can be calculated. These values are related to structural properties of the molecule under investigation, i.e. to the bond lengths and relative positions of the atoms, allowing to determine molecule by molecule the handedness of simple chiral species and other isomeric features.

For small chiral species, Coulomb Explosion Imaging provides a new approach to determine the handedness of individual molecules.

Hipoglisemi arasında ayırt etmek için bir araç olarak Coulomb patlama görüntüleme

This article shows how the COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) or the "reaction microscope" technique can be used to distinguish ...

Kimya

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving

We present a cooling method for a cold Fermi gas by parametrically driving atomic motions in a crossed-beam optical dipole trap (ODT). Our method employs the anharmonicity of the ODT, in which the hotter atoms at the edge of the trap feel the anharmonic components of the trapping potential, while the colder atoms in the center of the trap feel the harmonic one. By modulating the trap depth with frequencies that are resonant with the anharmonic components, we selectively excite the hotter atoms out of the trap while keeping the colder atoms in the trap, generating parametric cooling. This experimental protocol starts with a magneto-optical trap (MOT) that is loaded by a Zeeman slower. The precooled atoms in the MOT are then transferred to an ODT, and a bias magnetic field is applied to create an interacting Fermi gas. We then lower the trapping potential to prepare a cold Fermi gas near the degenerate temperature. After that, we sweep the magnetic field to the noninteracting regime of the Fermi gas, in which the parametric cooling can be manifested by modulating the intensity of the optical trapping beams. We find that the parametric cooling effect strongly depends on the modulation frequencies and amplitudes. With the optimized frequency and amplitude, we measure the dependence of the cloud energy on the modulation time. We observe that the cloud energy is changed in an anisotropic way, where the energy of the axial direction is significantly reduced by parametric driving. The cooling effect is limited to the axial direction because the dominant anharmonicity of the crossed-beam ODT is along the axial direction. Finally, we propose to extend this protocol for the trapping potentials of large anharmonicity in all directions, which provides a promising scheme for cooling quantum gases using external driving.

We present a parametric driving method to cool an ultracold Fermi gas in a crossed-beam optical dipole trap. This method selectively removes high-energy atoms from the trap by periodically modulating the trap depth with frequencies that are resonant with the anharmonic components of the trapping potential.

Periyodik Sürüş tarafından Optik tuzağa Ultracold Fermi Gaz Soğutma

We present a cooling method for a cold Fermi gas by parametrically driving atomic motions in a crossed-beam optical dipole trap (ODT). Our method employs ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

Yapısal Photoresponsive sıvı kristaller dinamikleri gözlemlemek için yeni teknikleri

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

We present a pump-probe method for preparing vibrational coherences in polyatomic radical cations and probing their ultrafast dynamics. By shifting the wavelength of the strong-field ionizing pump pulse from the commonly used 800 nm into the near-infrared (1200-1600 nm), the contribution of adiabatic electron tunneling to the ionization process increases relative to multiphoton absorption. Adiabatic ionization results in predominant population of the ground electronic state of the ion upon electron removal, which effectively prepares a coherent vibrational state (&#34;wave packet&#34;) amenable to subsequent excitation. In our experiments, the coherent vibrational dynamics are probed with a weak-field 800 nm pulse and the time-dependent yields of dissociation products measured in a time-of-flight mass spectrometer. We present the measurements on the molecule dimethyl methylphosphonate (DMMP) to illustrate how using 1500 nm pulses for excitation enhances the amplitude of coherent oscillations in ion yields by a factor of 10 as compared to 800 nm pulses. This protocol may be implemented in existing pump-probe setups through the incorporation of an optical parametric amplifier (OPA) for wavelength conversion.

We present a protocol for probing ultrafast vibrational coherences in polyatomic radical cations that result in molecular dissociation.

Polyatomic radikal katyonlar güçlü alanlı adyabatik iyonlaşma ile Ultrafast titreşim Coherences ölçümü

We present a pump-probe method for preparing vibrational coherences in polyatomic radical cations and probing their ultrafast dynamics. By shifting the ...

Construction and Operation of a Light-driven Gold Nanorod Rotary Motor System

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and artificial nanomotors and may provide new routes towards single cell analysis, studies of non-equilibrium thermodynamics, and mechanical actuation of nanoscale systems. A facile way to drive rotation is to use focused circularly polarized laser light in optical tweezers. Using this approach, metallic nanoparticles can be operated as highly efficient scattering-driven rotary motors spinning at unprecedented rotation frequencies in water.
In this protocol, we outline the construction and operation of circularly-polarized optical tweezers for nanoparticle rotation and describe the instrumentation needed for recording the Brownian dynamics and Rayleigh scattering of the trapped particle. The rotational motion and the scattering spectra provides independent information on the properties of the nanoparticle and its immediate environment. The experimental platform has proven useful as a nanoscopic gauge of viscosity and local temperature, for tracking morphological changes of nanorods and molecular coatings, and as a transducer and probe of photothermal and thermodynamic processes.

Plasmonic gold nanorods can be trapped in liquids and rotated at kHz frequencies using circularly-polarized optical tweezers. Introducing tools for Brownian dynamics analysis and light scatteringspectroscopy leads to a powerful system for research and application in numerous fields of science.

İnşaat ve ışık tahrik altın Nanorod Rotary Motor sistemi

The possibility to generate and measure rotation and torque at the nanoscale is of fundamental interest to the study and application of biological and ...

Light-driven Molecular Motors on Surfaces for Single Molecular Imaging

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces are demonstrated. This work requires careful design, considerable synthetic effort, and proper analysis. The rotary motion of the molecular motor in solution is shown by 1H NMR and UV-vis absorption spectroscopy techniques. In addition, the method to graft the motor onto an amine-coated quartz is described. This method helps to gain more insight into molecular machines.

The manuscript describes how to synthesize and graft a molecular motor on surfaces for single molecular imaging.

Işık odaklı moleküler motorlar yüzeylerde tek moleküler görüntüleme için

The design and synthesis of a synthetic system that aims for the direct visualization of a synthetic rotary motor at the single molecule level on surfaces ...

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species in the ppm-to-single-percent range. The main purpose of the method is the spatially resolved detection of low-concentration species, which have no transitions in the visible or near-IR spectral range that could be used for detection. IR-DFWM is a nonintrusive method, which is a great advantage in combustion research, as inserting a probe into a flame can change it drastically. The IR-DFWM is combined with upconversion detection. This detection scheme uses sum-frequency generation to move the IR-DFWM signal from the mid-IR to the near-IR region, to take advantage of the superior noise characteristics of silicon-based detectors. This process also rejects most of the thermal background radiation. The focus of the protocol presented here is on the proper alignment of the IR-DFWM optics and on how to align an intracavity upconversion detection system.

Here, we present a protocol to perform sensitive, spatially resolved gas spectroscopy in the mid-infrared region, using degenerate four-wave mixing combined with upconversion detection.

Kızılötesi dejenere dört-dalga ile kantitatif gaz algılama için Upconversion algılama karıştırma

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species ...