Pulse width effect on the dissociation probability of CH_4^+ in the intense femtosecond laser field  

作　　者：WANG Cao SONG Di LIU Yuyan KONG Fan'ao 

机构地区：[1]Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China [2]Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China [3]Graduate School of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Chinese Science Bulletin》2006年第10期1269-1272,共4页

摘　　要：The laser pulse width effect on the dis- sociation probability of CH4+ irradiated by an ultrafast laser has been investigated experimentally and theoretically. The femtosecond laser at 800 nm with an intensity of 8.0 × 1013 W/cm2 was used. The ob- served relative yield of the primary fragment ion CH3+ increases with increasing pulse width and tends to saturate when the pulse width is longer than 120 fs. The field-assisted dissociation (FAD) model and quasi-classical trajectory (QCT) calculation were ap- plied to predicting the dissociation probability of CH4+. The calculated probability is corrected with the mo- lecular orientation effect and the spatial distribution of laser intensity. The modified results show that the dissociation requires at least 23 fs and saturates with long pulse widths (≥100 fs). The result is ap- proximately consistent with the experimental observa- tion.The laser pulse width effect on the dissociation probability of CH4^＋ irradiated by an ultrafast laser has been investigated experimentally and theoretically. The femtosecond laser at 800 nm with an intensity of 8.0 × 10^13 W/cm^2 was used. The observed relative yield of the primary fragment ion CH3^＋ increases with increasing pulse width and tends to saturate when the pulse width is longer than 120 fs. The field-assisted dissociation （FAD） model and quasi-classical trajectory （QCT） calculation were applied to predicting the dissociation probability of CH4^＋. The calculated probability is corrected with the molecular orientation effect and the spatial distribution of laser intensity. The modified results show that the dissociation requires at least 23 fs and saturates with long pulse widths （1〉100 fs）. The result is approximately consistent with the experimental observation.

关 键 词：毫微微秒激光器 强激光区 甲烷 离解概率 激光脉冲宽度 

分 类 号：TN24[电子电信—物理电子学]