Effect of thermal defocusing on backward stimulated Raman scattering in CH4

	Effect of thermal defocusing on backward stimulated Raman scattering in CH4
	Xiao-qing Hua; Jing Leng; He-ping Yang; Guo-he Sha; Cun-hao Zhang
刊名	chinese journal of chemical physics
	2006-06-27
卷号	19 期号:3 页码:193-196
关键词	Nd : YAG laser stimulated Raman scattering thermal defocusing effect CH4 gas
通讯作者	沙国河
产权排序	1;1
英文摘要	the conversion efficiency of stimulated raman scattering (srs) in ch4 is studied by using a single longitudinal mode second-harmonic nd:yag laser (532 nm, linewidth 0.003 cm(-1), pulse-width (fwhm) 6.5 ns). due to the heat release from vibrationally excited particles, srs processes often suffer from the thermal defocusing effect (tde). in view of 6.5 ns laser pulse width is much shorter than the vibrational relaxation time of ch4 molecules, tde can only affect the srs processes afterwards. in the cases of low laser repetition, tde will be not serious. because it will be removed by the thermal diffusion in raman medium before the next pulse arrives. at the laser repetition rate 2 hz, ch4 pressure 1.1 mpa and pump laser energy 95 mj, the quantum conversion efficiency of backward first-stokes (bs1) has attained 73%. this represents the highest first-stokes conversion efficiency in ch4. furthermore, due to the relaxation oscillation, the bs1 pulses are narrowed to about 1.2 ns. as a result, the bs1 peak power turns out to be 2.7 times that of the pump. its beam quality is also much better and is only slightly affected by tde. this reason is that bsi represents a wave-front-reversed replica of the pump beam, which can compensate the thermal distortions in raman amplify process. under the same conditions, but pump laser repetition rate as 10 hz: the conversion efficiency of bs1 goes down to 36% due to tde. from this study, we expect that a well-behaved 630 ran raman laser may be designed by using a closed ch4/he circulating-cooling system, which may have some important applications.
WOS标题词	science & technology ; physical sciences
类目[WOS]	physics, atomic, molecular & chemical
研究领域[WOS]	physics
收录类别	SCI
原文出处	true
语种	英语
WOS记录号	WOS:000238867600003
公开日期	2010-11-30
内容类型	期刊论文
源URL	[http://159.226.238.44/handle/321008/97413]
专题	大连化学物理研究所_中国科学院大连化学物理研究所
作者单位	Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Mol React Dynam, Dalian 116023, Peoples R China
推荐引用方式 GB/T 7714	Xiao-qing Hua,Jing Leng,He-ping Yang,et al. Effect of thermal defocusing on backward stimulated Raman scattering in CH4[J]. chinese journal of chemical physics,2006,19(3):193-196.
APA	Xiao-qing Hua,Jing Leng,He-ping Yang,Guo-he Sha,&Cun-hao Zhang.(2006).Effect of thermal defocusing on backward stimulated Raman scattering in CH4.chinese journal of chemical physics,19(3),193-196.
MLA	Xiao-qing Hua,et al."Effect of thermal defocusing on backward stimulated Raman scattering in CH4".chinese journal of chemical physics 19.3(2006):193-196.