Picosecond and Nanosecond Pulse Shaping for State-Selective Chemistry

沃伦教授得到了 实验物理化学计划使用整形激光 在分子束中定向或排列分子的脉冲， 在低温晶体中产生粒子数反转，以及 通过光子锁定实验将能量定位在键中。 该研究计划的重点之一是开发 一种能有效填充电子激发的 状态，或者将人口转移到高度 基态的振动激发能级， 激光 这项工作的动机是研究 碰撞动力学需要选择性激发， 监测速度变化的碰撞。 完全人口 传输增强了信号并使干扰最小化。 成功地将大部分的热能 分布到高振动状态将是有用的， 探索化学反应的动力学 一个目标是 设计辐射场， 基态到旋转态的叠加， 在实验室中定向双原子分子。 一 调节解离速率的效果的演示 通过斯塔克移动先前稳定的水平， 具有特定的频率扫描脉冲形状将是第一个 将这项技术应用于多原子分子的一步。 %%% 通过准备特别定制的光脉冲， 产生简单和可解释的分子状态。 这些 技术将被沃伦教授用来控制他们的 分子束中的排列，甚至它们在 实验室，并调节它们分裂的速度 变成碎片

Professor Warren is supported by a grant from the Experimental Physical Chemistry Program to use shaped laser pulses to orient or align molecules in a molecular beam, to generate population inversion in low-temperature crystals, and to localize energy in a bond by a photon-locking experiment. One of the thrusts of the research program is the development of techniques to efficiently populate an electronically excited state with a single laser, or to transfer population to highly vibrationally excited levels of the ground state with two lasers. The motivation for this work is the study of collisional dynamics which require selective excitation to monitor velocity changing collisions. Complete population transfer enhances the signal and minimizes interferences. Success in transferring large fractions of the thermal distribution into high vibrational states will be useful for exploring the kinetics of chemical reactions. One goal is to design radiation fields which drive diatomic molecules in their ground state to a superposition of rotational states such that the diatomic molecule is oriented in the laboratory. A demonstration of the effect of modulating the dissociation rate of the IBr molecule by Stark shifting previously stable levels with specific frequency-swept pulse shapes will be the first step towards applying this technique to polyatomic molecules. %%% By preparing specially tailored pulses of light, it is possible to produce simple and interpretable states of molecules. These techniques will be used by Prof. Warren to control their alignment in a molecular beam and even their orientation in the laboratory, and to modulate the rate at which they break apart into fragments.