Direct IR Laser and Double Resonance Absorption Spectroscopyin Slit Supersonic Jets: Vibrational Dynamics of Novel Molecular Clusters

在实验物理化学计划的支持下，内斯比特教授正在研究喷射冷却、弱结合分子络合物的光谱、结构和动力学。这项工作利用关于振动跃迁的高分辨率光谱信息来帮助表征和理解对各种化学、生物和物理过程至关重要的弱分子作用力。Nesbitt的实验室将高灵敏度差分光束吸收技术与多通道红外探头几何结构和用于长程吸收的脉冲狭缝阀相结合，正在测量各种喷射冷却复合体的高分辨率亚多普勒振动光谱。正在研究的系统包括范德瓦尔斯和氢键二聚体，多原子分子的二聚体，以及与几个稀有气体原子结合的双原子分子。旋转分辨的振动泛音运动被泵浦，并用红外-红外双共振技术在氢键络合物中进行表征，由此产生的光碎片被探测到内态分布。利用对观测到的高分辨率光谱数据的量子力学模拟，提取了多维势表面的分子间势信息。

With support from the Experimental Physical Chemistry Program, Professor Nesbitt is investigating the spectroscopy, structure, and dynamics of jet cooled, weakly bound molecular complexes. This work exploits high resolution spectroscopic information on vibrational transitions to help characterize and understand the weak molecular forces so crucial to a variety of chemical, biological, and physical processes. Using a combination of high sensitivity differential beam absorption techniques with multipass infrared probe geometries and pulsed slit valves for long pathlength absorptions, Nesbitt's laboratory is measuring high resolution, sub-Doppler vibrational spectra of various jet cooled complexes. Systems being studied include van der Waals and hydrogen-bonded dimers, dimers of polyatomic molecules, and diatomic molecules bound to several rare gas atoms. Rotationally-resolved vibrational overtone motions are being pumped and characterized by infrared-infrared double resonance techniques in hydrogen-bonded complexes and the resulting photofragments probed for internal state distributions. Intermolecular potential information for multidimensional potential surfaces is being extracted using quantum mechanical simulations of the observed high resolution spectral data.