分子转动和激光脉冲对多光子激发控制的影响(英文)

用解析代数方法研究了分子转动和激光脉冲对双原子分子多光子激发控制的影响并推导得到不同转动通道下的分子振动激发几率的解析表达式.为了考察转动能级和考虑分子转动后与激光场夹角的变化对分子多光子振动激发和振动激发控制的影响,我们计算并比较了分子纯振动和加入分子转动两种情况,并分别给出了分子与极化激光场在不同取向角下三光子选择激发的图像.研究发现分子的转动能级对多光子非共振激发有修正作用,但是分子转动会降低多光子激发的选择性,而选择合适的激光脉冲形状有利于目标多光子激发控制的实现.文中还进一步讨论了激光脉冲初相位对分子多光子激发控制的影响,发现脉冲初相位对多光子激发过程有明显的调制作用.

Influences of Molecular Rotations and Laser Pulses on Controlling Multiphoton Excitation

The influence of molecular rotation, laser pulse shape and initial phase on controlling the infrared multiphoton excitation of diatomic molecules has been studied using an analytical algebraic approach, which involved the derivation of analytic transition probabilities with various rotational channels. To observe the correctional functions of the rotational energy and the relationship between the molecular orientation and the polarized direction of the laser field in terms of their impact on controlling multiphoton excitation, we calculated the probabilities in the purely vibrational and ro-vibrational cases. The maximumtransition probabilities were determined as a function of the time and molecular orientation angle in both cases for comparison, which allowed for the target multiphoton excitations to be achieved. However, oscillations appeared in the population of the ro-vibrational case which denoted rotational interference can decrease the selectivity of the molecular vibrational excitation. Furthermore, the rotational energy had a corrected action on multiphoton non-resonant excitation and the power of actions was dependent on the molecular anharmonicity. We have also provided a discussion of the influences of laser pulse shape and initial phase. We found that the use of an appropriate laser pluse shape afforded the target multiphoton excitation event, and that the initial phase of the chirped laser pulse had an obvious modulatory function on the multiphoton processes.