K(6S)+H_2→KH〔X^1∑^+(V=0,1)〕+H反应截面的测量

Measurement of the cross sections for the K(6S)+H_2→KH〔X^1∑^+(V=0,1)〕+H reaction

利用泵浦—检测技术,研究了K(6S)与H2反应生成的KH〔X1+(V,J)〕分子的转动态分布,利用激光感应荧光光谱(LIF),确定了v=0,1振动能级上的转动态分布。转动态分布与热统计分布基本一致。记录X1+(V,J)←A1+(V′,J+1)时间分辨荧光,从荧光强度的对数值给出的直线斜率得到它的自发辐射寿命。K激发态原子密度由激光能量吸收得到,反应生成物KH分子密度利用光学吸收法得到。由速率方程分析,得到σ(V,J),对J求和,得到的σ(v)分别为(1.4±0.6)×10-16cm2〔对v=0〕,σ(V)为(1.2±0.5)×10-16cm2〔对v=1〕。

Using a pump-probe method,the reaction of K（6S）and H2 has been studied.The nascent rotational distributions of KH（（v=0,1）,J）were determined from LIF spectrum.The rotational population profile was roughly consistent with a statistical distribution at the system temperature.The decay signal of time-resolved fluorescence from X^1∑＋（V,J）A^1∑＋（V′,J＋1） transitions was monitored.The semilog plot of the time-resolved fluorescence was shown.The slope yielded the spontaneous lifetime.The densities of K（6S） atoms excited by a pulse laser beam were evaluated directly from the laser energy loss which was absorbed by K atoms.The densities of KH molecules were measured by monitoring the absorption of a counter-propagating pulse dye laser beam,tuned to X1∑＋（V,J）A1∑＋ （V′,J＋1）transitions.Using a rate equation model,we obtain reactive cross sections σ（V,J）.The cross sections σ（V） are obtained by summing the individual cross sections σ（V,J）.The cross sections（in units of 10^-16cm^2） are（1.4±0.6） for v being 0 and（1.2±0.5） for v being l,respectively.