Laser Control of Molecular Conformation as an Avenue for Practical Laser Chemistry

美国弗吉尼亚大学的布鲁克斯·佩特（Brooks Pate）获得了实验物理化学项目的职业生涯资助，以开展激光控制分子构象的实用激光化学研究。这些研究的目标是选择性地填充单个分子构象结构，从而提高沿所需途径的反应速率。在双激光实验中，分子首先被激发到一个能量区，在这个能量区中，不同构象最小值周围的振动态通过分子内振动能量重分配（IVR）进行耦合。由于振动频率取决于构象，然后选择第二个（共振）激光来刺激发射到较低的状态。这个较低的能态低于IVR的起始能，因此最终的结构定位在一个期望的构象周围。人们对振动激发分子的构象所知甚少，但反应速率强烈地依赖于构象结构。这些技术将提供这种类型的第一个信息，因此可能导致真正突破性的结果。Pate教授的CAREER奖的教育部分将强调物理化学课程的发展，为那些对物理化学职业感兴趣的学生提供“研究培训”课程，在课程中更好地利用计算机，例如，用于问题处理的符号数学软件，以及在实验课程中结合现代研究仪器。

Brooks Pate of the University of Virginia has been awarded a CAREER grant in the Experimental Physical Chemistry Program to initiate studies of laser control of molecular conformations for practical laser chemistry. The goal of these investigations is to selectively populate a single molecular conformational structure, resulting in an enhanced reaction rate along the desired pathway. In the two-laser experiment, molecules are first excited to an energy region where the vibrational states localized around the different conformational minima are coupled through intramolecular vibrational energy redistribution (IVR). Since the vibrational frequencies depend on conformation, a second (resonant) laser is then selected to stimulate emission to a lower state. This lower energy state lies below the onset energy for IVR, hence the final structure is localized around the one desired conformation. Little is known about the conformations that a vibrationally excited molecule can assume, yet reaction rates are strongly dependent on the conformational structure. These techniques will provide the first information of this type and hence may lead to truly ground-breaking results. The educational component of Prof. Pate's CAREER award will emphasize the development of a physical chemistry course along the lines of a `research training` course for those students interested in physical chemistry careers, better utilization of computers in the curriculum, e.g., symbolic math software for problem manipulations, and incorporation of modern research instrumentation in the laboratory courses.