中文摘要：

本文研究了一维模型分子离子（初态为基态和一个激发束缚态叠加的相干态）在超强超短激光脉冲作用下的谐波发射谱．我们发现在高次谐波谱平台区域出现了周期性的结构变化．我们利用小波变换对谐波谱进行了暂态时间频率分析，结果表明该谐波结构产生的原因是由电离电子返回母离子时与不同束缚态复合而产生的谐波光脉冲之间相干叠加。同时采用半经典计算，对所得到的计算结果进行了分析，验证了我们的结论。

英文摘要：

We investigated the high order harmonic generation spectrum from an one dimensional molecular ion irradiated by an ultrashort and superintense laser pulse. Preparing the initial state of the ion in a coherent superposition of the ground state and an excited state of the ion, the harmonic spectrum is found exhibiting an unusual periodic structure in the high harmonic generation plateau. A wavelet time-frequency analysis shows that this structure is resulted from the ooherenee of two harmonic pulses generated by the ionized electrons combining with the ground state and the excited state, respectively. The three step model is adopted in our calculation, the calculation results are agree with the quantum calculation.