New time-resolved CARS arrangements

Summary Two techniques, using incoherent radiations of ns- or ps-pulse durations, respectively, used to obtain subps-time resolutions are described. Their advantages and limits are discussed. As a result both techniques should be used in addition to real fs-methods, because of their more simple arrangements and because of the possibility to determineT ₂-times of vibrations even if more than one vibration is simultaneously excited. Paper presented at the ?XI European CARS Workshop?, Florence, Italy, 23–25 March, 1992.     

K分子高激发振动能级 （V=46-61）与H分子间的碰撞能量转移

利用相干反斯托克斯拉曼光谱（CARS）探测技术,研究了K2的 （V=46-61）与H2间的电子-振转动能级的碰撞转移,扫描CARS谱确认了仅在H2的V=2,J=0,1,2及V=1,J=2能级上有布居,用n1,n2,n3,n4,分别表示(2,0) ,(2,1) ,(2,2) ,(1,2）上的粒子数密度,从CARS谱峰值得到n1／n4,n2／n4,n3／n4 分别为3.3±0.5,2.2±0.3,2.0±0.3,有88%粒子处在V=2能级上,而在V=1能级上有12%。转移能配置到振动,转动,平动的比例分别为0.53,0.01,0.46,能量主要分配在振动和平动上,在573K和5×103 Pa条件下,通过求解速率方程组和对时间分辨CARS线强度分析得到碰撞转移速率系数k12=(3.3±0.7) ×10-14 cm3s-1和k2=（1.4±0.3）×10-14cm3s-1。     

Phase‐locking of two independent degenerate coherent anti‐Stokes Raman scattering processes: concept,proposed all‐optical implementation,and potential applications

A novel approach toward phase‐locking of two independently produced yet energetically degenerate coherent anti‐Stokes Raman scattering (CARS) processes is put forward. The proposed all‐optical implementation involves a modified Mach–Zehnder interferometer, which is utilized to transfer phase coherence from three totally uncorrelated laser beams into two degenerate CARS beams that are produced in two distinct Raman active samples. Such a CARS interferometer based on coherent phase transport allows explicit measurement and control of phase differences between the two phase‐locked degenerate CARS processes, and hence may find applications in pertinent research fields such as CARS spectroscopy (tomography) as well as quantum information processing and transfer. Copyright © 2011 John Wiley & Sons, Ltd.     

Multimodal nonlinear optical microscopy

Because each nonlinear optical (NLO) imaging modality is sensitive to specific molecules or structures, multimodal NLO imaging capitalizes the potential of NLO microscopy for studies of complex biological tissues. The coupling of multiphoton fluorescence, second‐harmonic generation, and coherent anti‐Stokes Raman scattering (CARS) has allowed investigation of a broad range of biological questions concerning lipid metabolism, cancer development, cardiovascular disease, and skin biology. Moreover, recent research shows the great potential of using a CARS microscope as a platform to develop more advanced NLO modalities such as electronic‐resonance‐enhanced four‐wave mixing, stimulated Raman scattering, and pump‐probe microscopy. This article reviews the various approaches developed for realization of multimodal NLO imaging as well as developments of new NLO modalities on a CARS microscope. Applications to various aspects of biological and biomedical research are discussed.     

应用近红外可见光谱快速测量柴油十六烷值

快速测量十六烷值对检测柴油品质及控制炼制工艺具有重大意义。首先对采集到的381份柴油样品进行近红外可见光谱波段全光谱扫描,利用小波分析(WT)对原始数据进行去噪声处理,应用竞争性自适应重加权算法(CARS)进行特征波长选择,将CARS提取的22个特征波长输入至LS-SVM预测模型,决定系数r2为0.723,预测均方根误差RMSEP为1.878%。结果表明,使用WT-CARS变量选择算法获取光谱特征波长,结合LS-SVM建模,可以快速、准确的测量柴油中的十六烷值,为进一步实现柴油十六烷值的在线检测以及其他性能参数的快速测定奠定了基础。     

Raman spectroscopy and microscopy of individual cells and cellular components

Raman spectroscopy provides the unique opportunity to nondestructively analyze chemical concentrations in individual cells on the submicrometer length scale without the need for optical labels. This enables the rapid assessment of cellular biochemistry inside living cells, and it allows for their continued analysis. Here, we review recent developments in the analysis of single cells, subcellular compartments, and chemical imaging based on Raman spectroscopy. Spontaneous Raman spectroscopy provides for the full spectral assessment of cellular biochemistry, while coherent Raman techniques, such as coherent anti‐Stokes Raman scattering is primarily used as an imaging tool comparable to confocal fluorescence microscopy. These techniques are complemented by surface‐enhanced Raman spectroscopy, which provides higher sensitivity and local specificity, and also extends the techniques to chemical indicators, i.e. pH sensing. We review the strengths and weaknesses of each technique, demonstrate some of their applications and discuss their potential for future research in cell biology and biomedicine.     

Comparison of different CARS variants for concentration measurements in combustion research

Summary Different strategies are discussed to use CARS spectroscopy for measuring mole fractions of combustion species. The influence of various physical parameters on both shape and total intensity of spectral bands is studied. Two variants for concentration measurements are compared based either on spectralshape analysis or frequency-integrated intensity ratios. The analysis leads to the conclusion that concentrations from a spectral-shape fit are more sensitive to inaccuracies of input parameters than band intensities. Paper presented at the ?XI European CARS Workshop?, Florence, Italy, 23–25 March, 1992.     

Resonance CARS in solids

Summary Solid-state resonance CARS spectroscopy is applied to investigate the vibronic properties of polydiacetylene chains and of the permanganate ion. Results are presented for single crystals of the symmetrically substituted diacetylene FBS where few polymer chains are embedded in the host lattice built by the monomers and for the permanganate ion doped in potassium perchlorate single crystals. Particularly, spectra of the C=C and the C≡C stretching vibrations of the polymer chains and of the fully symmetric ν₁-breathing mode of the permanganate ion, recorded for different pump laser frequencies, have been investigated. For the polydiacetylenes a theoretical model is introduced which describes the excitation and line profiles. The model is based on a crude Born-Oppenheimer approximation. The electronic wave functions are calculated by means of an LCAO-MO method in the Hückel approach. The Franck-Condon integrals are calculated under the assumption of harmonic potential functions. The simulation of the CARS spectra is based on results of calculations of absorption and resonance Raman spectra obtained from the diacetylene single crystals. Paper presented at the “XI European CARS Workshop?, Florence, Italy, 23–25 March, 1992.     

Atomic beam deflection by coherent momentum transfer and the dependence on weak magnetic fields

The deflection of Ne atoms in the metastable state ³ P ₂ by coherent transfer of the momenta of 4 or 8 photons is demonstrated, based on the technique developed for coherent population transfer with delayed pulses (STIRAP). After deflection the intensity profile of the isotope of mass 20 is fully seperated from that for the undeflected atoms of mass 22. It is furthermore shown, how the interplay of Larmor precession of the electronic magnetic moment and the sequential deflection in two spatially separated zones can be used to measure the magnetic field, integrated over the flight-path between the transfer zones. Received: 1 October 1997 / Revised: 22 December 1997 / Accepted: 11 March 1998