一雙原子分子在雙頻強雷射脈衝下之諧波產生與解離

Abstract

實驗上一些分子在強度約1012W/㎝2的雷射脈衝照射下就有明顯的解離。研究顯示以一簡單的一維模型做線性變頻的數值計算之古典分析可以接近這個量子的結果。在此我們考慮一個雙原子分子在變頻雷射脈衝下的情況。解此非微擾量子力學問題的方法是首先使用p-FGH的方法求得無外加場下的本徵值與本徵函數，而後使用薛丁格表象的分離算子法去傳播外加場下的波函數，並研究三個物理量：本徵態的占有機率，解離率，偶極的加速度之時演與其諧波產生頻譜。由這些物理量，我們能對物質-場的交互作用之力學有一較清晰的瞭解。

There is significant dissociation probability for some molecules under laser pulse of intensity about 1012W/㎝2 experimentally. It was shown that numerical calculation of linearly chirped excitation of a 1-D molecular dissociation can be compared quantally and classically. Here we consider the case of a diatomic molecule under an intense chirped laser pulse. The method for solving the nonperturbative quantum problem is to obtain the eigenvalues and eigenfunctions of the stationary system by using Fourier grid Hamiltonian method (FGH) in p-space first. Then we use split-operator method in Schrodinger picture to propagate the wavefunction and study three physical quantities : the time evolution of population, dissociation probability and dipole acceleration and its harmonic generation spectrum. From these quantaties, we can have a clearer understanding of the matter-field interaction dynamics.