摘要
本文全面研究了CHCIF_2分子在9.4μm到10.6μm波长范围內强CO_2脉冲激光照射下的红外多光子吸收实验规律,获得在无碰撞和有碰撞条件下多光子吸收系数与激光频率、激光能量密度及气体压强的关系,观察到多步饱和、超线性吸收及窄共振等现象,证实在分子组合频率处有多光子吸收。利用包含某些碰撞效应的能量主方程对加入Ar气的多光子吸收做理论模拟,用蒙特卡洛法计算,与实验资料符合很好。研究表明CHC(?)F_2在高气压下的超线性吸收主要是激光激发和碰撞消激发多次反复竞争的结果。
The behavior of multiphoton absorption of CHC1F_2 molecule under the irradiation of intense CO_2 laser pulse in the wavelength range from 9.4μm to 10.6μm is reported in this paper. The multiphoton absorption coefficient under both collisionless condition and collision present condition was measured as fuctions of laser frequency, laser energy fluence and gas pressure. Stepwise saturation, superlinear absorption and narrow resonance phenomena were observed. Multiphoton absorption at combination frequency of the molecule was also verified. The EGME incorporating some pressure effects was used to simulate the experimental data on the CHC1F_2 excitation in Ar buffer gas. The EGME was numerically solved from trajectory calculations based on a Monte Carlo method. We found that the EGME successfully predicted the IR MPA of CHC1F_2 over a wide range of experimental parameters and that the super-linear absorption is mainly owing to the competition of laser excitation and collisional de-excitation
