Multiple-Pulse, Single-Shot Femtosecond Spectroscopy of Condensed Phases

在这个项目中的物理化学计划的化学 司，基思教授A。马萨诸塞州研究所的纳尔逊 技术将参与一系列持续的调查 分子和材料行为的光学控制领域，包括 凝聚介质中的结构和化学重排。 这些研究 依赖于在可见光下使用多脉冲飞秒光谱， 近红外或近紫外波长。 整形飞秒脉冲 序列将被用来驱动晶体中的大振幅振动 晶格，使光谱观察远离平衡 晶体几何形状 额外的工作将集中在开发 的自动时域振动光谱仪，操纵的 电子相干观测相干波包动力学 只有通过双光子跃迁才能达到的电子能级， 其他话题。 研究的最初阶段将致力于 实施改进的方法，用于生成，表征， 和放大复杂的飞秒波形。 当前物理化学的前沿研究包括 在超短时间尺度上的分子过程， 一个分子振动的周期（几飞秒）。 这些 调查有可能提供控制 分子反应和其他动力学过程，以及提供 核磁共振技术的光学类似物， 凝聚相光谱学

In this project in the Physical Chemistry Program of the Chemistry Division, Prof. Keith A. Nelson of the Massachusetts Institute of Technology will engage in a series of continuing investigations in the field of optical control of molecular and material behavior, including structural and chemical rearrangements in condensed media. These studies rely on the use of multiple-pulse femtosecond spectroscopy at visible, near-infrared or near-ultraviolet wavelengths. Shaped femtosecond pulse sequences are to be used to drive large-amplitude vibrations in crystal lattices to enable the spectroscopic observation of far-from-equilibrium crystal geometries. Additional work will concentrate on the development of an automated time-domain vibrational spectrometer, the manipulation of electronic coherences to observe coherent wavepacket dynamics in electronic levels accessible only through two-photon transitions, and other topics. The initial stages of the research will be devoted to the implementation of improved methods for the generation, characterization, and amplification of complex femtosecond waveforms. Current forefront research in physical chemistry includes the study of molecular processes at ultra-short time scales that correspond to the period of one molecular vibration ( a few femtoseconds). These investigations have the potential of providing methods for the control of molecular reactions and other dynamical processes, as well as providing optical analogs of the nuclear magnetic resonance technique to study condensed phase optical spectroscopy.