Laser-induced Alignment and Coulomb Explosion of CO2
Laser-induced Alignment and Coulomb Explosion of CO2作者机构：State Key Laboratory for Mesoscopic Physics Department of Physics Peking University Beijing 100872China
出 版 物：《Chinese Journal of Chemical Physics》 (化学物理学报（英文）)
年 卷 期：2009年第22卷第6期
页 面：571-576,J0001页
核心收录：
学科分类：080901[工学-物理电子学] 07[理学] 0809[工学-电子科学与技术（可授工学、理学学位）] 08[工学] 080401[工学-精密仪器及机械] 070203[理学-原子与分子物理] 0804[工学-仪器科学与技术] 0803[工学-光学工程] 0702[理学-物理学]
基 金：V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (No.20603001 No.10534010 and No.10821062) and the National Basic Research Program of China (No.2006CB806007)
主 题：Rotational wave-packet Field-free alignment Coulomb explosion
摘 要：Dynamic processes of CO2 are experimentally studied in intense femtosecond laser fields with laser intensity varying from 1×10^13 W/cm^2 to 6×10^14 W/cm^2. When the laser intensity is below the ionization threshold, a coherent rotational wave-packet is formed for CO2 at room temperature through nonadiabatic rotational excitation. The evolution of the wave-packet leads to transient alignment. The field-free alignment revives periodically after the laser pulse is over. The revival structure can be modified by a second laser pulse for the rotational wave-packet through precisely adjusting the time delays between the two laser pulses. When the laser intensity excesses the ionization threshold, ionization and Coulomb explosion occur. The atomic ions C^m＋ （re=1-3） and On＋ （n=1-3） observed in the experiment exhibit highly anisotropic angular distributions relative to the laser polarization. Using two linearly polarized laser pulses with crossed polarization, we conclude that the anisotropic angular distribution results from dynamic alignment, in which the rising edge of the laser pulse aligns the neutral CO2 along the laser polarization direction prior to ionization.
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