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

在实验物理化学项目的支持下，Nesbitt教授正在研究喷射冷却的弱结合分子复合物的光谱学、结构和动力学。这项工作利用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力。Nesbitt的实验室将高灵敏度差分光束吸收技术与多通红外探针几何形状和用于长径吸收的脉冲狭缝阀相结合，测量了各种射流冷却复合物的高分辨率、亚多普勒振动光谱。正在研究的体系包括范德华和氢键二聚体，多原子分子的二聚体，以及与几种稀有气体原子结合的双原子分子。利用红外双共振技术对氢键配合物中的旋转分辨振动泛音运动进行了泵浦和表征，并对产生的光碎片进行了内部态分布探测。利用量子力学模拟观测到的高分辨率光谱数据，提取了多维势面分子间电位信息。

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.