IR-Vis SFG-CD Studies on the Chiral Structure of Surface Molecules

研究了基底表面分子的红外-可见和频圆二色性。用LBO晶体对原有的ps-YAG激光器和OPG/OPA系统进行了改造，使其具有更高的效率，并能更好地研究分子的手性。利用YAG基频光和OPA闲频光在AgGaS_2晶体上的差频，获得了红外激光输出。我们在可见光中插入四分之一波片，产生左右偏振光，然后与红外光混合，得到SFG-CD信号，实验所用样品为铁电和反铁电液晶分子。我们成功地获得了10个分子层厚样品的SFG-CD信号，而不是单分子层样品。为了克服这个困难，我们已经改变了可见光（2co）光束的紫外线。

We have investigated IR-Vis Sum-Frequencey-Generation Circular Dichroism of the molecules on the substrate surface. This technique may provide 1 08 more efficiency than any other kinds of techniques to study the chirarity of molecules.We have reformed our old conventional ps-YAG laser and OPG/OPA system with LBO Crystal. We obtained IR laser beams by taking differential frequency of a fundamental YAG and the idler beam of OPA on a AgGaS2 crystal. We have inserted a quarter-wave plate into a visible beam to make left and right polarized light, and then mixed with the IR beam to obtain SFG-CD signal.The samples used in the experiment were ferro- and antiferro- electric liquid crystal molecules. We have successfully obtained SFG-CD signal for 1 0 molecular layers thick samples, but not for a single molecular layer sample. To overcome this difficulty we have changed the visible (2co) beam to UV.