Presidential Young Investigator Award/Molecular Dynamics and Energy Transfer in Photochemical Reactions

劳里·巴特勒博士得到了总统青年研究员格兰特的资助，他的工作是研究被激光辐射激发的气相分子的光碎裂。巴特勒博士正在研究分子中两个发色团之间快速的偶极子-偶极子诱导的电子能量转移。特别是，她正在研究1,2- c2f4bri碎片中这种能量转移的性质，其中C-I和C-Br在初始激发到C-Br排斥表面后裂变竞争。这项工作是特别重要的，因为如果这种分子内的能量转移可以被抑制，人们可能会想到选择性激发和单个键的断裂。巴特勒博士还利用解离分子的发射光谱学来研究改变多原子分子解离途径的排斥性电子态之间的交叉点。在巴特勒博士的实验室中进行的测量提供了这种非绝热离解的详细数据，从而可以确定核间分离、相对速度、交叉点的电子能量以及到达交叉点所需的时间。巴特勒博士的研究解决了一些基本问题，这些问题是关于初始电子激发可能在许多能量允许的解离通道中导致特定解离通道的过程。通过测量产品的速度、内能和产品的角分布，她可以直接解决有关激光激发产生的电子能量再分配的问题。

Dr. Laurie Butler is supported by a Presidential Young investigator Grant form the Physical Chemistry Program to study photofragmentation of gas phase molecules which have been electronically excited with laser radiation. Dr. Butler is studying the rapid dipole-dipole induced transfer of electronic energy between two chromophores in a molecule. In particular, she is studying the nature of this energy transfer in 1,2-C2F4BrI fragmentation in which C-I and C-Br fission compete following initial excitation to the C-Br repulsive surface. This work is particularly important since, if this intramolecular energy transfer could be suppressed, one might conceive of selective excitation and fragmentation of individual bonds. Dr. Butler is also utilizing emission spectroscopy of dissociating molecules to study intersections between repulsive electronic states which alter the dissociation pathways of polyatomic molecules. Measurements made in Dr. Butler's laboratory provide detailed data on such nonadiabatic dissociations thus permitting the determination of internuclear separation, relative velocity, and electronic energy at the crossing as well as the time required to reach the crossing. Dr. Butler's research is addressing fundamental questions regarding the process by which an initial electronic excitation may result in specific dissociation channels among many energetically allowed ones. By measuring product velocities, internal energies, and angular distributions of products, she can directly address qustions regarding the redistribution of electronic energy produced by laser excitation.