Fourier Transform Limited IR Source

点击翻译按钮获取中文摘要

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.