飞秒和频光谱系统的研制

Abstract

和频光谱是一种具有表面选择性的高灵敏表面光谱检测手段.研制的飞秒和频光谱系统由一个飞秒(10-15 S)脉宽的红外光和一个皮秒(10-12 S)脉宽的可见光共同作用于样品,在这两个入射场频率之和处产生和频信号.该系统既可以获取表面和界面上分子的振动光谱、分子取向等重要信息,做到亚单分子层检测,同时还具有很好的时间分辨能力,可以用来研究表面分子的超快过程.

Sum frequency generation(SFG) spectroscopy is a surface selective and high sensitive optical surface/interface probe.The SFG signal of our newly developed femtosecond sum frequency generation(FS-SFG)spectroscopy system is generated at a frequency which is the sum of 2 incident light fields,a femtosecond(10-15 s) infrared light and a picosecond(10-12 s) visible light.FS-SFG can provide vibrational spectroscopy and molecular orientation of molecules on surfaces and interfaces,and sensitive enough for sub-monolayer detection.Furthermore,FS-SFG provides high time-resolution,and can by used for study of ultrafast processes of molecules on surfaces and interfaces.The light sources used for our FS-SFG setup covers a large spectral band,briefly,visible from 280 nm to 900 nm,and mid-infrared from 2.6 μm to 20 μm.FS-SFG can measure a >160 cm-1 spectral band at any setting infrared wavelength,with a~7 cm-1 spectral resolution.