纳秒强激光场中甲醇光电离产生高价离子的研究  

Generation of multi-charged ions in laser-induced ionization of methanol under intense nanosecond laser fields

作　　者：孔祥蕾[1] 罗晓琳[1] 牛冬梅[1] 张先燚[1] 阚瑞峰[1] 李海洋[1] 

机构地区：[1]中国科学院安徽光学精密机械研究所环境光谱学实验室,合肥230031

出　　处：《物理学报》2004年第5期1340-1345,共6页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :2 0 0 73 0 42 );国家高技术研究发展计划 (批准号 :2 0 0 1AA64 10 40 )资助的课题~~

摘　　要：利用 2 5ns脉冲Nd YAG 5 32nm的激光 ,在 10 1 1 W·cm- 2 的光场强度下 ,利用飞行时间质谱对He ,N2 ,Ar载气条件下甲醇的激光电离过程进行了研究 .发现当利用氩作为载气时 ,除观察到一般多光子电离所产生的离子和碎片离子外 ,还观察到很强的Cq + (q =2 - 4 )和Oq + (q=2— 4 )高价离子 .这些离子都有很高的平动能 ,通过改变载气种类和压力以及使用不同延迟条件的脉冲电场的实验 ,可以认为这些高价离子来源于含甲醇团簇的库仑爆炸过程 .这些实验结果为发展库仑爆炸理论研究提供新思路 .The photoionization of methanol seeded in He, N 2, Ar gases by an intense 25ns Nd-YAG 532nm laser has been studied by time-of-flight mass spectrometry. At the laser intensity about 10 11W·cm -2, strong multi-charged ions C q+(q2—4) and O q+(q2—4) appeared in the mass spectra apart from the ions coming from multi-photon ionization (MPI) process when Ar was used as a carrier gas. From the simulation, we can find the velocity of multi-charged ions is distributed in Gaussian shape with a FWHM of 6.4×104 m/s. From the experimental results of changing carrier gases and changing the delay time of the pulsed electric field, the conclusion can be drawn that those multi-charged ions come from the Coulomb explosion of methanol cluster ions.

关 键 词：甲醇分子 纳秒激光 高价离子 库仑爆炸 质谱图 

分 类 号：O432.12[机械工程—光学工程]