纳秒强激光场中苯电离产生高价离子的研究

Generation of Multi-charge Carbon Ions in Laser-induced Ionization of Benzene under Intense Nanosecond Laser Fields

用25ns脉冲Nd-YAG532nm的激光,在1010～1011W·cm-2的光场强度下,利用飞行时间质谱对He、N2、Ar载气条件下苯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C+2、C2H2+、C3H3+、C6H6+离子外,还观察到很强的Cq+(q=1～3)高价离子.这些离子都有很高的平动能,C2+的最可几平动能为12.9eV,C3+为37.5eV.通过改变载气种类和压力及在不同光场强度条件下的实验,可以认为这些高价离子来源于含苯团簇的库仑爆炸过程.

The photoionization of benzene seeded in He, N-2, Ar gases by an intense 25 ns Nd-YAG 532 nm. laser has been studied by time-of-flight mass spectrometry. At the laser intensity about 10(10) similar to 10(11) W . cm(-2), strong multi-charged ions Cq+ (q = 1 similar to 3) appeared in the mass spectra when Ar was used as carrier gas. From the peak splitting, the most probable kinetic energies of C2+ and C3+ are calculated to be 12.9 eV and 37.5 eV, respectively. From the experimental results of changing the He, N-2, Ar carrier gases, their pressure and the laser intensity, we can draw the conclusion that those multi-charge ions come from the Coulomb explosion of benzene cluster ions.