로버트 버거 (Philipps 대학 Marburg, 독일)를 감사 우리가 우리의 데이터와 분자 카이랄성의 해석에 대 한 논의 일반적 영감. 우리는 제공 하는 샘플에 대 한 ZHAW Wädenswil (스위스)에서 줄리아 Kiedrowski 알렉산더 Schießer와 마이클 Reggelin TU 다름슈타트 (독일)에서 뿐 아니라 벤자민 Spenger, 마누엘 Mazenauer, Jürgen Stohner 감사.
프로젝트 초점 ELCH (랄 시스템의 전자 역학)와 연방 교육부의 연구 (BMBF) 아래 과학 · 경제 우수 헤센 주 이니셔티브에 의해 지원 되었다. MS는 아돌프 메 재단이 재정 지원을 인정 한다.

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저자 아무 경쟁 관심사를 선언합니다.

때문에 다양 한 구성 요소, COLTRIMS 설치 필요 전문 기술, 진공 기술, 입자 감지, 빠른 전자 및 데이터 분석의 분야에서 특히의 다소 높은 수준을 합니다. 하기 전에 복잡 한 종족의 수사에, 그것은 따라서 수 철저 하 게 확인 한다 설치 예: 수행 하 고 2 원자 또는 triatomic 종에 측정 분석 하 여 제대로 실행 되는 경우.
레이저 펄스와 분자 제트 오버랩의 기간과 강도 최적화 ?...

카이랄성은 150 년 이상에 대 한 매혹적인 연구 된 우리의 본성의 기능입니다. 19토 륨 세기, 파스퇴르, van't Hoff 등 분자 슈퍼-imposable-우리의 왼쪽 손과 오른쪽 처럼 되지 않은 두 개의 미러 이미지 구조에서 발생할 수 있습니다 발견. 이 속성 '랄', '손'에 대 한 그리스어 단어에서 불리 했다.
지금까지, 열역학 속성 또는 왼쪽 및 오른 형태 (는 두 ' 상체')의 에너지 레벨 차이가 발견 되었습니다. 주어진된 샘플의 handedness를 분석 하 고는 상체 분리, 다른 카이 랄 분자와 상호 작용 사용할 수 있습니다, 예를 들어 다양 한 chromatographical 방식에서 이루어집니다. 1 (진동) 원형이 색 성, (V) CD 등 광 회전 분산, 오드, Chiroptical 방법 정기적으로 상체를 구분 하기 위해 고용 됩니다. 2
그것은 미세한 구조의 결정에 관해서 라면, 이러한 기술 예: 양자 화학 계산에서에서 추가 정보가 필요. 직접 절대 구성 결정에 널리 허용 되는 유일한 기술이 이다 변칙 엑스레이 회절. 3
그것은 최근에 보였다 간단한 카이 랄의 절대적인 구성 쿨롱 폭발 영상에 의해 결정 될 수 있다. 4 , 5 이 방법에서는, 기체에서 분자는 곱하면 이온 수 있도록 나머지 코어는 강력 하 게 서로 격퇴. 이 반발 분자의 빠른 조각화 ('폭발') 이끌어 낸다. 방향과 크기-작은 분자에 대 한 분자의 구조를 조각 결합체 상관의 운동량 방향 일치 의외로 잘 본드 축. 분자 구조 결정에 대 한 쿨롱 폭발은 분자 이온 빔 가속기에서를 사용 하 여 개척 되었습니다. 6 이 빔 포 일 기술은 최근에 랄 인식에 대 한 적용. 7
변칙 엑스레이 회절, 반대로 샘플 결정 하지만 가스 단계에서 제공 되지 않아야 합니다. 이것은 쿨롱 폭발 접근 휘발성 종족에 대 한 적합 하 고 따라서 x 선 회절을 보완 합니다. 경우에 따라 handedness도 개별 분자에 대 한 확인할 수 있습니다.
실제로, 분자 구조의 정확한 재건 메탄 파생 상품, 예를 들면 중앙 탄소와 다른 치환 기 분자에도 어려운 입증 했다. 이것은 사실 조각 사이 상호 작용은 정확히 Coulombic 모든 채권 동시에 휴식에 기인 합니다. 특히 상체, 사이 구별을 stereochemical 정보를 얻기 위하여이 재건 다행히 필요는 없습니다. 대신, 다른 파편의 기세 벡터 수익률은 왼쪽 및 오른 분자에 대 한 수량 상관 될 수 있다. 신뢰할 수 있는 결과를 얻으려면, 적어도 4 개의 단편 결합체를 기록 해야 합니다.
이 기세 정보를 측정 하기 위해서는 한-그리고 한-분자 휴식-최대에서 파편 단일 측정 단계에서 검색 될 수 있다. 이 상태는 일반적으로 '일치 검색' 이라고 합니다. 또한, 방출 방향 있다 분석할 시간과 조각의 위치를 기록 하는 것에 금액 리스트 모드 데이터 형식에 영향을.
원자와 분자 물리학, 기술 개발 되었다 대량 분리 및 시간 및 위치에 민감한 멀티 히트 탐지기 정전기 분석기를 사용 하 여 측정의이 접근을 구현 하는. 가장 눈에 띄는 COLTRIMS (찬 대상 반동 이온 추진력 분광학) 설치-라고 반응 현미경입니다. 8 , 9 실험의이 종류에 대 한 스케치는 그림 1에서 주어진 다. 뿐만 아니라 전자를 기록할 수 있는 표준 COLTRIMS, 반대로 쿨롱 폭발 이미징 이온 검출기를을 요구 한다.
분석기와 검출기 초고 진공에서 마운트 (&#60; 1 x 10-9 hPa) 잔류 가스에서 이온의 생성을 피하기 위해. 샘플의 단일 분자 만든 초음속 팽창에 의해 가스 무료 분자 jet를 통해 제공 됩니다: 증기압, 덕 분자 진공으로 소형 노즐 (약 50 µ m 직경) 통해 확장. 실험, 소스 챔버의이 부분은 일반적으로 두 개의 스키와 차동 펌핑된 단계 상호 작용 영역에서 분리 된다. 추가 섹션을 펌핑 차동은 가스 제트기를 덤프 하 고 따라서 상호 작용 영역에 배경 가스를 피하기 위해 상호 작용 지역 뒤에 위치 해 있습니다.
이온화 방사선 분자 제트 미만 90 °로 교차합니다. 싱크 로트 론 방사선, 빠른 이온 또는 전자 충격 가능한 '발사체' 쿨롱 폭발을 유도 하는 있지만 대부분 실험실 요즘 펨 레이저 펄스를 사용 합니다.
다음 프로토콜은 이온과 펨 레이저의 일치 이미징에 대 한 실행 설치 실험실에서 사용할 수 있는 가정 합니다. 4 개 또는 5 개의 조각으로 쿨롱 폭발을 유도 하는 데 필요한 최대 강도 6 x 1014 W/c m2의 순서 여야 합니다. 상당히 긴 측정을 방지 하려면 레이저의 반복 속도 10khz 이상 이어야 한다. 이것이 중요 한 한편으로, 일치 탐지 수만 수 ascertained 레이저 초점의 조각화에 대 한 확률은 크게 레이저 펄스 (이상적으로 하지 10% 이상) 당 1 아래 경우 때문에. 총 조각화 비율, 다른 한편으로, 해서는 안됩니다 몇 kHz 보다 낮은 있기 때문에 관련 multifragmentation 통로의 공유는 일반적으로 10-4. 으로 장려 사실 원리 이미 단일 조각 이벤트는 enantiopure 샘플의 구성을 식별 하기에 충분 및 몇 백의 그 검출에 상체의 풍부를 결정 하기 위해 수 있습니다 언급 해야 한 알 수 없는 enantiomeric 구성의 샘플입니다.

<table><tbody><tr><td>CHBrCl2</td><td>SigmaAldrich</td><td>139181-10G</td><td>or other suitable sample</td></tr><tr><td>femtosecond laser system</td><td>KMLabs</td><td>Wyvern500</td><td></td></tr><tr><td>High-reflective mirrors</td><td>EKSMA</td><td>042-0800</td><td></td></tr><tr><td>mirror mounts</td><td>Newport</td><td>U100-A-LH-2K&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>focusing mirror (protected silver, f = 75 mm)</td><td>Thorlabs&amp;nbsp;</td><td>CM254-075-P01</td><td>(if available: f = 60 mm)</td></tr><tr><td>COLTRIMS spectrometer, including electronics and data acquisition system</td><td>RoentDek</td><td>custom</td><td>contrary to the standard COLTRIMS, only one detector is needed</td></tr></tbody></table>

coulomb explosion imaging as a tool to distinguish between stereoisomers

이 기사에서는 COLTRIMS (찬 대상 반동 이온 추진력 분광학) 또는 "반응 현미경" 기술을 사용 하는 방법을 개별 분자의 수준에서 간단한 카이 랄의 상체 (stereoisomers) 사이 구별 하. 이 방법에서는, 샘플의 기체 분자 제트 진공 챔버로 확장 하 고 펨 (fs) 레이저 펄스와 교차. 펄스의 강도 높은 여러 이온화, 여러 양이온 (긍정적으로 위탁된) 파편을 생성 하는 소위 쿨롱 폭발 점화를 빨리 이끌어 낸다. 정전기 필드 가이드 시간 및 위치에 민감한 검출기에 이러한 양이온. 시간의 비행 질량 분석기와 마찬가지로, 각 이온의 도착 시간 그것의 질량에 대 한 정보를 생성합니다. 흑자로 정전기 필드는 방출 방향과 조각화 후 운동 에너지 이어질 유사 비행 시간 및 영향 위치 검출기에 방식으로 조정 됩니다.
각 이온 충격 감지기;에 전자 신호를 생성 이 신호는 높은 주파수 전자 처리 하 고는 컴퓨터에서 이벤트에 의해 이벤트를 기록. 등록 된 데이터는 영향 시간과 위치에 해당합니다. 이러한 데이터는 에너지와 각 조각의 방출 방향을 계산할 수 있습니다. 이러한 값은 조사, 즉 채권 길이 결정 분자에 의해 분자 다른 이성질체 기능과 간단한 카이 랄 종의 handedness를 수 있도록 원자의 상대적 위치를 분자의 구조적 속성 관련이 있습니다.

이 부분에서 우리는 halomethanes에 대 한 결과 보여줍니다. 이러한 종의 원리 증명 실험 그들의 단순 하 고 높은 증기 압력 때문에 이상적입니다. 한편, 더 복잡 한 종 halothane 여러 이온화를 유도 하는 싱크 로트 론 소스에서 단일 소프트-x-선 광자를 사용 하 여 조사 했다. 14
CHBrClF
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Watch this Scientific Journal Video about Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers at JoVE.com

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Stereoisomers 사이 구별 하는 도구로 쿨롱 폭발 영상

작은 키 랄 종에 대 한 쿨롱 폭발 이미징 개별 분자의 handedness를 결정 하는 새로운 접근을 제공 합니다.

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

coulomb-explosion-imaging-as-tool-to-distinguish-between

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Organic Chemistry

Chemistry

Unit 1

Transition Metals and Coordination Complexes

Stereoisomerism

SCIENTISTS IN ACTION

9.0K 조회수.  Goethe-Universität Frankfurt am Main. 작은 키 랄 종에 대 한 쿨롱 폭발 이미징 개별 분자의 handedness를 결정 하는 새로운 접근을 제공 합니다.

비디오: Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

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 ...

연구

공학

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

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 ...

화학

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

F− 의 310 Nm 분리에 의해 설명 하는 음이온의 광전자 이미징

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

Using a Cyclic Ion Mobility Spectrometer for Tandem Ion Mobility Experiments

Accurate characterization of chemical structures is important to understand their underlying biological mechanisms and functional properties. Mass spectrometry (MS) is a popular tool but is not always sufficient to completely unveil all structural features. For example, although carbohydrates are biologically relevant, their characterization is complicated by numerous levels of isomerism. Ion mobility spectrometry (IMS) is an interesting complement because it is sensitive to ion conformations and, thus, to isomerism. 
Furthermore, recent advances have significantly improved the technique: the last generation of Cyclic IMS instruments offers additional capabilities compared to linear IMS instruments, such as an increased resolving power or the possibility to perform tandem ion mobility (IMS/IMS) experiments. During IMS/IMS, an ion is selected based on its ion mobility, fragmented, and reanalyzed to obtain ion mobility information about its fragments. Recent work showed that the mobility profiles of the fragments contained in such IMS/IMS data can act as a fingerprint of a particular glycan and can be used in a molecular networking strategy to organize glycomics datasets in a structurally relevant way. 
The goal of this protocol is thus to describe how to generate IMS/IMS data, from sample preparation to the final Collision Cross Section (CCS) calibration of the ion mobility dimension that yields reproducible spectra. Taking the example of one representative glycan, this protocol will show how to build an IMS/IMS control sequence on a Cyclic IMS instrument, how to account for this control sequence to translate IMS arrival time into drift time (i.e., the effective separation time applied to the ions), and how to extract the relevant mobility information from the raw data. This protocol is designed to clearly explain the critical points of an IMS/IMS experiment and thus help new Cyclic IMS users perform straightforward and reproducible acquisitions.

Ion mobility spectrometry (IMS) is an interesting complement to mass spectrometry for the characterization of biomolecules, notably because it is sensitive to isomerism. This protocol describes a tandem IMS (IMS/IMS) experiment, which allows the isolation of a molecule and the generation of the mobility profiles of its fragments.

탠덤 이온 이동성 실험을 위한 순환 이온 이동성 분광계 사용

Accurate characterization of chemical structures is important to understand their underlying biological mechanisms and functional properties. Mass ...

Direct Comparison of Hyperspectral Stimulated Raman Scattering and Coherent Anti-Stokes Raman Scattering Microscopy for Chemical Imaging

Stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS) microscopy are the most widely used coherent Raman scattering imaging technologies. Hyperspectral SRS and CARS imaging offer Raman spectral information at every pixel, which enables better separation of different chemical compositions. Although both techniques require two excitation lasers, their signal detection schemes and spectral properties are quite different. The goal of this protocol is to perform both hyperspectral SRS and CARS imaging on a single platform and compare the two microscopy techniques for imaging different biological samples. The spectral focusing method is employed to acquire spectral information using femtosecond lasers. By using standard chemical samples, the sensitivity, spatial resolution, and spectral resolution of SRS and CARS in the same excitation conditions (i.e., power at the sample, pixel dwell time, objective lens, pulse energy) are compared. The imaging contrasts of CARS and SRS for biological samples are juxtaposed and compared. The direct comparison of CARS and SRS performances would allow for optimal selection of the modality for chemical imaging.

This paper directly compares the resolution, sensitivity, and imaging contrasts of stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS) integrated into the same microscope platform. The results show that CARS has a better spatial resolution, SRS gives better contrasts and spectral resolution, and both methods have similar sensitivity.

화학 이미징을 위한 하이퍼스펙트럼 자극 라만 산란 및 일관된 안티스토크스 라만 산란 현미경의 직접 비교

Stimulated Raman scattering (SRS) and coherent anti-Stokes Raman scattering (CARS) microscopy are the most widely used coherent Raman scattering imaging ...

Differential Imaging of Biological Structures with Doubly-resonant Coherent Anti-stokes Raman Scattering (CARS)

Coherent Raman imaging techniques have seen a dramatic increase in activity over the past decade due to their promise to enable label-free optical imaging with high molecular specificity 1. The sensitivity of these techniques, however, is many orders of magnitude weaker than fluorescence, requiring milli-molar molecular concentrations 1,2. Here, we describe a technique that can enable the detection of weak or low concentrations of Raman-active molecules by amplifying their signal with that obtained from strong or abundant Raman scatterers. The interaction of short pulsed lasers in a biological sample generates a variety of coherent Raman scattering signals, each of which carry unique chemical information about the sample. Typically, only one of these signals, e.g. Coherent Anti-stokes Raman scattering (CARS), is used to generate an image while the others are discarded. However, when these other signals, including 3-color CARS and four-wave mixing (FWM), are collected and compared to the CARS signal, otherwise difficult to detect information can be extracted 3. For example, doubly-resonant CARS (DR-CARS) is the result of the constructive interference between two resonant signals 4. We demonstrate how tuning of the three lasers required to produce DR-CARS signals to the 2845 cm-1 CH stretch vibration in lipids and the 2120 cm-1 CD stretching vibration of a deuterated molecule (e.g. deuterated sugars, fatty acids, etc.) can be utilized to probe both Raman resonances simultaneously. Under these conditions, in addition to CARS signals from each resonance, a combined DR-CARS signal probing both is also generated. We demonstrate how detecting the difference between the DR-CARS signal and the amplifying signal from an abundant molecule's vibration can be used to enhance the sensitivity for the weaker signal. We further demonstrate that this approach even extends to applications where both signals are generated from different molecules, such that e.g. using the strong Raman signal of a solvent can enhance the weak Raman signal of a dilute solute.

Differential Imaging of Biological Structures with Doubly-resonant Coherent Anti-stokes Raman Scattering CARS

A combination of three single wavelength short-pulsed lasers is used to generate coherent anti-Stokes Raman scattering (CARS) and doubly-resonant CARS (DR-CARS). The difference between these signals provides enhanced sensitivity for otherwise difficult to detect coherent Raman signals, enabling imaging of weak Raman scatterers.

이중 - 공진 코히어런트 반 스톡스 래맨 산란 (자동차)와 생물 학적 구조의 차동 영상

Coherent Raman imaging techniques have seen a dramatic increase in activity over the past decade due to their promise to enable label-free optical imaging ...

생물학

VSFG 현미경을 사용하여 다중 모드, 신속, 초분광 화학 분석

Multimodal Nonlinear Hyperspectral Chemical Imaging Using Line-Scanning Vibrational Sum-Frequency Generation Microscopy

Vibrational sum-frequency generation (VSFG), a second-order nonlinear optical signal, has traditionally been used to study molecules at interfaces as a spectroscopy technique with a spatial resolution of ~100 &#181;m. However, the spectroscopy is not sensitive to the heterogeneity of a sample. To study mesoscopically heterogeneous samples, we, along with others, pushed the resolution limit of VSFG spectroscopy down to ~1 &#181;m level and constructed the VSFG microscope. This imaging technique not only can resolve sample morphologies through imaging, but also record a broadband VSFG spectrum at every pixel of the images. Being a second-order nonlinear optical technique, its selection rule enables the visualization of non-centrosymmetric or chiral self-assembled structures commonly found in biology, materials science, and bioengineering, among others. In this article, the audience will be guided through an inverted transmission design that allows for imaging unfixed samples. This work also showcases that VSFG microscopy can resolve chemical-specific geometric information of individual self-assembled sheets by combining it with a neural network function solver. Lastly, the images obtained under brightfield, SHG, and VSFG configurations of various samples briefly discuss the unique information revealed by VSFG imaging.

저자 스포트라이트: Mesoscopically Heterogeneous Self-Assembled Structures 연구에서 VSFG 현미경의 잠재력 공개 

A multimodal, rapid hyperspectral imaging framework was developed to obtain broadband vibrational sum-frequency generation (VSFG) images, along with brightfield, second harmonic generation (SHG) imaging modalities. Due to the infrared frequency being resonant with molecular vibrations, microscopic structural and mesoscopic morphology knowledge is revealed of symmetry-allowed samples.

라인 스캐닝 진동 합계-주파수 생성 현미경을 사용한 다중 모드 비선형 초분광 화학 이미징

Vibrational sum-frequency generation (VSFG), a second-order nonlinear optical signal, has traditionally been used to study molecules at interfaces as a ...

Stereoisomers

On the basis of mirror symmetry, stereoisomers of an organic molecule can be further classified into diastereomers and enantiomers. Diastereomers are stereoisomers that are not mirror images of each other. Substituted alkenes, such as the cis and trans isomers of 2-butene, are diastereomers, as these molecules exhibit different spatial orientations of their constituent atoms, are not mirror images of each other,&#160;and do not interconvert. Here, the interconversion is suppressed due to restricted rotation around the &#960; bond. Another class of diastereomers &#8212; those without &#960; bonds &#8212; are molecules that have non-superposable spatial orientations and exhibit different configurations of their substituent groups at some, but not all, stereocenters. For example, cis-1,2-dimethylcyclohexane and trans-1,2-dimethylcyclohexane are diastereomers, as these molecules are not superposable and have a different configuration of the methyl and hydrogen groups at only one out of their two stereocenters.
Enantiomers are stereoisomers that are mirror images of each other. As only chiral molecules can have non-superposable mirror images, enantiomers are chiral molecules. For example, the chiral molecule 2-butanol and its mirror image are enantiomers, as these molecules exhibit non-superposable spatial orientations of their constituent atoms and are mirror images of each other. A chiral molecule and its mirror image are collectively referred to as an enantiomeric pair, or a pair of enantiomers. The enantiomer of a chiral molecule can be drawn by taking its mirror image from any position or&#160;exchanging the positions of two of the substituents at each stereocenter of the molecule.

Stereoisomers: Diastereomers and Enantiomers

스테레오소머스

On the basis of mirror symmetry, stereoisomers of an organic molecule can be further classified into diastereomers and enantiomers. Diastereomers are ...

Stereoisomers 사이 구별 하는 도구로 쿨롱 폭발 영상

요약

더 많은 비디오 탐색

이 비디오의 챕터

분자 순응및 클러스터의 공간 분리

레이저 기반 초고속 분자 회전의 직접 이미징

F⁻ 의 310 Nm 분리에 의해 설명 하는 음이온의 광전자 이미징

탠덤 이온 이동성 실험을 위한 순환 이온 이동성 분광계 사용

화학 이미징을 위한 하이퍼스펙트럼 자극 라만 산란 및 일관된 안티스토크스 라만 산란 현미경의 직접 비교

이중 - 공진 코히어런트 반 스톡스 래맨 산란 (자동차)와 생물 학적 구조의 차동 영상

라인 스캐닝 진동 합계-주파수 생성 현미경을 사용한 다중 모드 비선형 초분광 화학 이미징

라인 스캐닝 진동 합계-주파수 생성 현미경을 사용한 다중 모드 비선형 초분광 화학 이미징

라인 스캐닝 진동 합계-주파수 생성 현미경을 사용한 다중 모드 비선형 초분광 화학 이미징

스테레오소머스