We report on the observation of resonance enhanced high-order harmonic generation (HHG) from a dense medium composed of indium or tin nanoparticles. Unlike previous studies of resonance enhanced high harmonics from laser produced plasma plume from a prepulse, we generate HHG directly, thus eliminating the undesired contributions from various components in the plasma. We discuss the mechanisms for our observed resonance effect in the absence of preionized particles and the implications of the experimental results on the HHG mechanism in metal nanoparticles.

中文翻译：

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飞秒脉冲直接激发金属纳米粒子引起的共振增强高次谐波的观察

我们报告了从由铟或锡纳米颗粒组成的致密介质中共振增强的高次谐波产生（HHG）的观察结果。与先前对激光产生的预脉冲产生的等离子体羽流产生的共振增强高次谐波的研究不同，我们直接生成HHG，因此消除了等离子体中各种成分的不良影响。我们讨论了在没有预离子化颗粒的情况下观察到的共振效应的机理，以及实验结果对金属纳米颗粒中HHG机理的影响。