中文摘要：

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。

英文摘要：

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.