Fourier Transform Limited IR Source

我们建议购买傅里叶变换有限纳秒脉冲红外激光光源，以增强现有分子束表面散射设备的能力。脉冲放大的连续波环形染料激光器与注入种子的Nd：YAG激光器的基本原理一起用于差频产生，其输出随后被用NbO_3或β-BaB_3进行光学参数放大。这种光源在2.0-0.8微米的近红外范围内提供了无与伦比的光谱亮度--窄带宽和高脉冲能量。利用这种激光器，小分子中许多第一和第二泛音跃迁可以饱和，允许有效的布居转移到v=2或3。从这些高度非谐的振动状态，现有的设备基础设施将被用于随后的近红外泛音激发，产生振动激发至少达到v=6的分子束。这样，将实现一种新的光泵浦光抽运方式，即泵浦激发。可行性计算表明，这种方法既适用于氢化物，如HCl，也适用于重原子双原子化合物，如CO，NO。以这种方式产生的分子束将被用于对电子非绝热分子-表面相互作用的性质进行实验。

We propose to purchase a Fourier-Transform Limited nanosecond-pulsed infrared laser light source to enhance the capabilities of an existing molecular beam surface scattering apparatus. A pulse amplified cw-ring dye laser is used with the fundamental of an injection-seeded Nd:YAG laser for difference frequency generation, the output of which is subsequently amplified in an optical parametric process using Lithium Niobate or ß-Barium Borate. This light source provides unparalleled spectral brightness – narrow bandwidth and high pulse energy – in the near infrared from 2.0-0.8 µm. With this laser many 1st and 2nd overtone transitions in small molecules can be saturated, allowing efficient population transfer to v=2 or 3. From these highly anharmonic vibrational states, the already existing equipment infrastructure will be used for subsequent near IR overtone excitation, producing molecular beams with vibrational excitation at least up to v=6. In this way a new means of optical pumping for beam-surface scattering, namely PUMP-PUMP excitation, will be implemented. Feasibility calculations show that this approach is viable both for hydrides, e.g. HCl, as well as heavy atom diatomics, e.g. CO, NO. Molecular beams produced in this way will be used to carry out experiments on the nature of electronically nonadiabatic molecule-surface interactions.