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).

<ol>
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The authors have nothing to disclose.

본 절차는 슬릿 기반의 2 차원 영상으로 설정 분자 회전 실시간 동영상을 캡처 우릴 수있다. 관찰 된 이온은 슬릿을 통과하기 때문에, 단계 1.5 중요한 단계 중 하나입니다. 슬릿 블레이드의 가장자리가 선명해야합니다. 작은 결함이있는 경우, 이러한 슬릿 0.3 mm의 함몰 등의 스크래치 이온 이미지 (도 6)이 관찰된다. 이러한 경우에, 슬릿 블레이드는 000 그릿 습식 사포로 연마되어야한다...

깊은 이해와 분자의 동적 특성의 더 나은 사용을 위해, 분명 관심의 분자 운동을 시각화하는 것이 필수적이다. 시분 쿨롱 폭발 촬상이 대물 1, 2, 3을 달성하기 위해 강력한 방법 중 하나이다. 이 방식에서, 관심있는 분자 역학 펌프 초단파 레이저 필드가 시작한 후 시간 지연된 펄스 프로브로 프로빙한다. 프로브의 조사에 의해 분자가 이온화 승산되며 쿨롱 반발력으로 인해 단편 이온으로 분해. 배출 된 이온의 공간 분포는 프로브 조사의 분자 구조 및 공간 방향의 척도이다. 펌프 프로브 지연 시간을 측정하는 스캐닝 시퀀스는 영화 분자의 생성을 이끈다. 그것은 주목할만한, 즉 가장 간단한 경우에 - 이원자 분자 - 배출 된 이온의 각도 분포직접 분 자축 분포 (즉, 제곱 회전 파동 함수)를 반영한다. 펌프 공정에 대해서는, 초단 레이저 필드를 사용하여 분자 운동의 간섭 제어의 최근 진보는 고도로 제어 된 회전 웨이브 패킷 (4)의 작성, (5)에 인도하고있다. 또한, 회전 방향으로 적극적으로 분극 제어 된 레이저 필드 6, 7, 8을 이용하여 제어 될 수있다. 이는 따라서 쿨롱 폭발 영상 법은 이러한 펌프 공정 9, 10, 11, 12, 13과 결합 될 때 파 본성 포함한 분자 회전의 상세한 그림이 가시화 될 수있는 것으로 기대되고있다. 그러나 일부시간은 아래에 언급 된 바와 같이, 기존의 촬상 방법과 관련된 실험 문제가 발생. 본 연구의 목적은 이러한 어려움을 극복 분자 회전 웨이브 패킷의 고품질 영화를 만드는 새로운 방법을 제공하는 것이다. 물리적 인 의미와 함께, 본 발명의 방법으로 촬영 분자 1 회전 실험 영화는 이전 용지 (11)에 제시 하였다. 개발의 배경 본 영상 법의 구체적인 이론 측면에서, 그리고 다른 기존의 기술과의 비교는 다가오는 논문에서 설명한다. 여기서는 주로 일반적인 펌프 프로브 광 설치 조합하고 새로운 촬상 장치를 구비 한 프로 시저의 실용적이고 기술적 인 측면에 초점을 맞출 것이다. 이전 논문에서와 같이, 타겟 시스템은 단방향 질소 분자 (11)를 회전한다. 의 주요 어려움 실험개략적으로도 1에 도시 된 촬상 설정 기존 검출기의 위치, 또는 카메라 앵글과 관련이있다. 회전축 레이저 필드 유도 분자의 회전에 관계되는 레이저 전파 축 (6), (7, 8)와 일치하기 때문에, 회전축을 따라 검출기를 설치 실용적이지 않다. 레이저 조사를 피하기 위해, 검출기가 설치 될 때, 상기 카메라 각도 회전 측 관찰에 대응한다. 이 경우에는, 투사 (2D) 이미지 이온 분자 (14)로부터의 원래 방향을 복원하는 것은 불가능하다. 의 3D 이미지 검출기 (14), 15, 16, 17, 18, 19, 상단 검출기 이온 IMPAC되는 도달 시간t의 위치를 측정 할 수 쿨롱 폭발 영상 (10), (12)를 사용하여 직접 분자 회전을 관찰하는 독특한 방법을 제공했다. 그러나, 레이저 샷 당 허용되는 이온 개수는 고화질 (14)의 분자 운동이 긴 동영상을 생성하기 어렵다는 것을 의미 차원 검출기의 하한 (전형적으로 &lt;10 이온)이다. 검출기 (전형적 NS)의 데드 타임은 이미지 해상도 이미징 효율에 영향을 미친다. 또한 &lt;~ 1 kHz의 레이저 반복률로 실시간 이온 이미지를 모니터함으로써 양호한 펌프 프로브 빔 중첩을 간단한 작업이 아니다. 여러 그룹들이 3 차원 기술을 사용하여 회전 웨이브 패킷을 관찰 하였지만, 상기 공간 정보에 한정 및 / 또는 직접 복잡한 노드 구조를 포함하는 파장 특성의 상세한 시각화, 12 (10)를 달성 아니었다. 의 본질새로운 이미징 기술은도 1에서 &quot;새로운 카메라 앵글&quot;의 사용이다. 2 차원 검출기는 회전축 방향으로부터 관찰 선도, 회전 평면에 평행하면서이 구성에서, 검출기에 레이저 빔 노출을 회피한다. 슬릿은 이미지에 기여할 회전 평면에서만 이온 (레이저 펄스의 편광면)을 허용한다. 차원 검출기보다 카운트 속도 (일반적으로 100 ~ 이온)를 제공하는 2 차원 검출기가 사용될 수있다. 측정 효율이 높은 반면, 전자의 설정은, 3D 검출의 경우에 비해 간단하다. 시간이 많이 소요되는 등 아벨 반전 (14) 수학 재건은, 또한 각도 정보를 추출하는 데 필요하지 않습니다. 이러한 기능은 측정 시스템의 쉽게 최적화 고품질 영화의 생산 리드. 표준 2D / 3D 하전 입자 촬상 장치를 용이하게 본 witho 설치하도록 변형 될 수있다고가의 장비를 사용하는 유타.

<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

우리는 레이저 유도 분자 초고속 회전 파동 패킷 역학을 가시화하는 방법을 제시한다. 우리는 지금까지-비실용적 카메라 앵글을 실현하는 새로운 2 차원 쿨롱 폭발 촬상 설정을 개발 하였다. 우리의 영상 기법에서, 이원자 분자는 원 편광 강한 레이저 펄스로 조사된다. 토출 원자 이온 레이저 전파 수직 가속된다. 레이저 편광면 거짓말 이온이 기계적 슬릿을 사용하여 선택하고, 높은 처리량과 묘화되는 2 차원 검출기는 편광면에 평행하게 설치된. 원형 편광 (등방성) 쿨롱 폭발 펄스가 사용되기 때문에, 토출 된 이온의 관찰 각도 분포를 직접 펄스 조사시의 제곱 회전 파동 함수에 상당한다. 분자량 회전 실시간 동영상을 생성하기 위해, 본 영상 법은 펨토초 펌프 프로브 O와 결합ptical 설정이있는 펌프 펄스는 단방향 분자 앙상블을 회전 만듭니다. 인하여 우리의 검출 시스템의 높은 화상 처리량 펌프 프로브 실험 조건은 쉽게 실시간 스냅 샷을 모니터링함으로써 최적화 될 수있다. 그 결과, 관찰 영화의 품질은 움직임의 구체적인 파장 특성을 시각화 충분히 높다. 또한, 본 기술은 광범위한 수정 없이도 분자 시스템의 새로운 카메라 앵글이나 관점을 제공하는 기존의 표준 이온 촬상 설정으로 구현 될 수 있다는 점에 유의하라.

도 4a는 하나의 프로브 레이저 총에 걸리는 N 2 + 프로브 조사 (쿨롱 폭발)에 배출 이온의 프로브 전용 원시 이미지를 보여줍니다. 각 밝은 장소는 하나의 이온에 해당합니다. 도 4b는 10,000 치화 원 카메라 화상의 가산 영상을 나타낸다. 이러한 이미지는 우리의 촬상 설치 편광면 내의 모든 방향 각의 분자를 모니터링 할 수 있음을 보여?...

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.

레이저 기반 초고속 분자 회전의 직접 이미징

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

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Chemical Bonding: Molecular Geometry and Bonding Theories

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9.6K 조회수.  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.

비디오: 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.

생활 세포의 분자 Rotors의 형광 수명 이미징

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

연구

생체공학

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.

분자 순응및 클러스터의 공간 분리

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

공학

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.

원적외선 레이저 방출 및 그들의 주파수의 측정을 특성화

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.

Stereoisomers 사이 구별 하는 도구로 쿨롱 폭발 영상

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

화학

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.

정기 간행물 운전하여 광학적 갇혀 초저온 페르미 가스를 냉각

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.

Photoresponsive 액정의 구조 역학을 관찰을 위한 새로운 기술

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 급진적인 양이온으로 강한 분야 단 열 이온화에 초고속 진동 일관성의 측정

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.

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.

빛 주도 분자 모터 표면에 단일 분자 이미징

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.

적외선 타락 한 4 웨이브 혼합 양적 가스 감지에 대 한 업 검출

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