环境气体种类对激光烧蚀粒子速度劈裂的影响

Influence of gas type on velocity splitting of ablated particles

采用蒙特-卡罗(Monte Carlo)方法,模拟了激光烧蚀粒子输运动力学过程,在环境气体压强为100 Pa的情况下,研究了环境气体种类(He,Ne,Ar和假想气体等)对烧蚀粒子速度劈裂的影响.研究结果表明,在四种环境气体中传输的烧蚀粒子均出现了速度劈裂现象,形成速度劈裂所需时间按He,Ne,假想气体和Ar的次序减小.还研究了环境气体分子的质量和半径对烧蚀粒子速度劈裂的影响,形成速度劈裂所需时间随环境气体分子半径(或质量)增大而减小.在假想气体中,两速度峰强度相等时的强度最小.结合欠阻尼振荡模型和惯性流体模型,对劈裂的形成时间进行了解释.所得结论可为进一步定量研究纳米晶粒生长机理提供基础.

The transport dynamics of the ablated particles is simulated via Monte Carlo simulation.The influences of ambient gases（He, Ne,and Ar dummy gas） on velocity splitting of the ablated particles under 100 Pa are investigated.The results show that the velocity splitting appears in four types of gases.The formation times of velocity splitting of the ablated particles decrease in sequence of He,Ne, dummy gas and Ar.The influences of the mass and radius of ambient gas molecule on the velocity splitting are also investigated.The formation time of the velocity splitting decreases with mass/radius of ambient gas molecule increasing.The intensity is the smallest when the two velocity peak intensities are equal.The formation time of velocity splitting is explained by the underdamping oscillation model and the inertia fluid model.These results give a good foundation for the further study of the Si nanoparticle growth.