纳秒强激光中乙腈团簇增强的高价电离及其波长效应  

Wavelength Effect of Cluster-assistant Multiple Ionization of Seeded Acetonitrile Beam in Nanosecond Intense Laser

作　　者：邵士勇[1] 肖雪[2] 李海洋[3] 

机构地区：[1]中国科学院安徽光学精密机械研究所大气光学中心 [2]中国科学院安徽光学精密机械研究所环境光学与技术重点实验室,安徽合肥230031 [3]中国科学院大连化学物理研究所,辽宁大连116023

出　　处：《质谱学报》2007年第3期129-135,共7页Journal of Chinese Mass Spectrometry Society

基　　金：国家自然科学基金(批准号:20573111);国家863课题(2002AA649010;2001AA640302)资助

摘　　要：利用脉宽为25ns的脉冲Nd：YAG1064nm和532nm激光，在10^10～10^11W·cm^-1强度下，用飞行时间质谱对乙腈分子柬激光电离过程进行研究，均发现高价态的原子离子，N^q＋（q=1～5）和C^q＋（q=1～4），但两种激光场中的高价离子规律明显不同。实验结果表明，高价离子可能来源于乙腈团簇的库仑爆炸过程。提出一个多光子电离引发，逆韧致吸收加热-电子碰撞电离模型来解释高价离子的产生。在这个模型中，波长越长越有利于电子能量的逆韧致吸收，导致高价电离与波长紧密相关。To investigate the relationship between laser wavelength and multi-charged ions, the photo-ionization of acetonitrile molecular beam carried out by helium was studied on time-of-flight mass spectrometry using 25 ns, 532 nm and 1 064 nm Nd-YAG laser with intensity of 10^10-10^11 W· cm^-2. Multi-charged ions were all observed when laser beam irradiates with the dense portion of the pulsed molecular beam, but it was obvious that the rule of multi-charged ions was completely different in the two laser fields. An electron re-scattering and re-colliding ionization model is proposed to explain the appearances of those multiple charged ions under such low laser intensity. The longer wavelength facilities the energy absorption rate during inverse bremsstrahlung, which leads to the resulting wavelength dependence of the multi-charged atomic ions.

关 键 词：乙腈团簇 高价离子 多光子电离 库仑爆炸 波长效应 飞行时间质谱 

分 类 号：O657.63[理学—分析化学] O644[理学—化学]