Absorption linewidth measurement of reactive molecular electrinic states by nonlinear optical spectroscopy.

我们用XeCl准分子激光器和二次谐波晶体相结合的脉冲放大方法，对连续掺钛宝石激光器的输出进行脉冲放大，获得了200 MHz线宽的高分辨率紫外光。利用该紫外光测量了氧气氛下激光烧蚀产生的SiO~(2+)离子吸收光谱的多普勒线宽，以研究离子在膨胀烧蚀等离子体中的平动运动。通过分析，我们再现了理论计算中所期望的烧蚀等离子体的振荡。我们将利用该系统对反应电子态进行光谱研究。

We have produced high resolution UV light of 200MHz linewidth by a pulse anplification of the output of a CW Ti : Sapphire laser with a XeCl excimer laser conbined with a second harmonic crystal. The linewidth is only one fifth of the commercial pulsed dye laser and it will be highly effective for the precise linewidth measurement of absorption spectra.By using this UV light, we have measured Doppler linewidth of the absorption spectra of SiO^+ produced by laser ablation under oxygen atmosphere in order to investigate translational motion of ion in expanding ablation plasma. From the analysis, we have reproduced oscillation of ablation plasma which was expected from theoretical calculation.We are going to use this system for the spectroscopic study of reactive electronic states.