N2分子在强激光场中的场致电离

研究了在强激光脉冲中各种不同取向的N2分子发生场致电离的电离几率和表观电离效率.用量子化学方法计算了N2+分子离子在各种不同取向上的势能曲线,然后用传递矩阵方法得到了N2分子在不同方向上的电离几率,经过角度平均之后得到了各种取向的所有N2分子的总电离几率,并对计算结果进行了激光时间和空间修正.用800nm和70fs的激光脉冲对N2分子进行了在强激光场中的电离实验,得到了N2分子电离后产生的电子的角度分布图和电离几率随激光功率密度变化的关系曲线.实验结果和理论计算结果符合得很好.

Field Ionization of N2 Molecule in Strong Laser Field

The field-assisted ionization of N 2 molecules in strong laser pulse was investigated. The theoretical ionization probabilities and the apparent ionization efficiencies with different angles are studied. The potential surfaces of N + 2 ions along different orientations were calculated by the ab initio method. The predicted ionization probabilities were obtained with the computation of tunneling efficiency by using the transfer matrix method. The probabilities were modified by the laser spatial and temporal corrections. The results agree with the observations in an experiment with a 800 nm and 70 fs laser. The yield dependences of laser intensity and of polarization plane are coincident with the theoretical predictions.