Picosecond and Nanosecond Laser Pulse Shaping for State-Selective Chemistry

Dr. Warren S.沃伦得到了 物理化学计划开发新的激光脉冲整形 和脉冲序列技术进行光谱研究 气相和凝聚相的分子种类。 这项工作的新颖之处来自于使用增强的 控制激光辐射场以产生简单且 各种各样的可解释的分子状态 应用. 沃伦在理论上和实践中都证明了这一点。 在实验上，可以产生成形脉冲， 脉冲序列具有皮秒分辨率，高功率， 完全相位控制。 他还证明， 将需要特征形状来解决特定的 分子问题，如振动的选择性激发 状态、光密度补偿和弛豫效应 在气体和分子晶体中， 而不使用分子束。 这些技术被用于各种研究。 例如，两个不同颜色的整形脉冲被 用于选择性地和完全地泵浦高振动态 在碘，从而允许研究两个速度变化 碰撞和反应的演变， 氧碘激光器 成形深紫外脉冲加可见光脉冲 被用来表征弯曲的可能性， HCP的光化学 局域分子激发 1，4-二溴萘被泵入以研究 光纤中孤子传输 最后，光子回波序列 正在进行研究，以给出独立于 光密度效应和分子间相互作用 有机晶体

Dr. Warren S. Warren is supported by a grant from The Physical Chemistry Program to develop new laser pulse shaping and pulse sequencing techniques for spectroscopic studies of molecular species in both gas and condensed phases. The novel aspect of this work comes from the use of enhanced control over the laser radiation field to produce simple and interpretable molecular states in a wide variety of applications. Warren has demonstrated both theoretically and experimentally that it is possible to produce shaped pulses and pulse sequences with picosecond resolution, high powers, and complete phase control. He has also demonstrated which characteristic shapes would be required to solve specific molecular problems such as selective excitation of vibrational states, compensation for optical density and relaxation effects in both gases and molecular crystals, and velocity selection without the use of molecular beams. These techniques are being used in a variety of studies. For example, two shaped pulses of different colors are being used to selectively and completely pump high vibrational states in iodine, thus permitting study of both velocity changing collisions and the evolution of the reaction which powers the oxygen-iodine laser. Shaped deep-UV pulses plus visible pulses are being used to characterize the bending potential and photochemistry of HCP. Localized molecular excitations of 1,4-dibromonaphthalene are being pumped in order to study soliton propagation in fibers. Finally, photon echo sequences are being studied to give undistorted decays independent of optical density effects and molecular interactions in mixed organic crystals.