Internal Rotation Potential Surfaces

罗格斯大学的Lionel Goodman得到了实验物理化学项目的支持，继续他关于小非刚性分子和芳烃内旋的理论和实验研究。他将通过将他早期的松弛研究扩展到其他甲基分子和其他转子，来研究母体分子框架弯曲对内旋转势面的影响。与布鲁克海文的Mike White合作，将利用涉及里德堡跃迁和零动能光电子能谱的双光子射流光谱，获得基态、自由基阳离子和高位里德堡态扭转势垒的形状和高度信息。电子结构计算也将使用逐步弛豫来确定关键挠曲，并使用一些涉及极化和扩散函数的基集以及相关水平。分子中甲基的扭转运动目前正在进行深入的研究，因为它们为分子内振动能量再分配（IVR）问题提供了见解。通过激光激发控制化学反应的目标需要了解激发能量如何流入各种可能的反应通道。甲基扭转运动可以在光谱的可访问区域进行研究，并为跟踪IVR提供一维理论模型。

Lionel Goodman of Rutgers University is supported by the Experimental Physical Chemistry Program to continue his theoretical and experimental studies on internal rotation in small nonrigid molecules and aromatics. He will study the effect of flexing of the parent molecule frame on the internal rotation potential surfaces by extending his earlier relaxation studies to other methyl molecules and other rotors. Two-photon jet spectroscopy involving Rydberg transitions and zero-kinetic energy photoelectron spectroscopy, in collaboration with Mike White of Brookhaven, will be exploited to yield information on the shape and height of ground state, radical cation and high lying Rydberg state torsional potential barriers. Electronic structure calculations will also be undertaken using stepwise relaxations to determine the key flexings, and using a number of basis sets involving polarization and diffuse functions, and correlation levels. The torsional motions of methyl groups in molecules are presently under intensive investigation for the insight that they provide to the problem of intramolecular vibrational energy redistribution (IVR). The goal of controlling chemical reactions by laser excitation requires an understanding of how the excitation energy flows into various possible reaction channels. Methyl group torsional motions can be studied in an accessible region of the spectrum and offer a one dimensional theoretical model for tracking IVR.