激光烧蚀硅所生成的等离子体发射光谱特性

报道由Ｑ－开关Ｎｄ：ＹＡＧ激光器产生的１．０６μｍ、１０ｎｓ的脉冲激光辐射大气中的硅靶所产生的等离子体发射光谱的研究结果。当作用在硅靶表面的功率密度为９．３×１０９Ｗ／ｃｍ２时，测定了等离子体在２００～８８０ｎｍ波长范围内的时间分辨发射光谱。估计了等离子体点燃的时间，测定了等离子体中硅原子的推进速度，讨论了等离子体中Ｎ＋离子产生的原因。通过测量等离子体辐射谱线的半高宽随延迟时间的变化．得到等离子体中电子密度随时间的延迟近似地以ｅｘｐ（－ｔ１／２）的关系衰减。

The Plasma Emission Spectrum of Laser-ablated Silicon in Air

Time-resolved emission spectrum from laser-produced plasmas by 1.06μm, 10ns laser pulse's irradiation on silicon target surface in air at a flux of 9.3×109 W/cm2 isrecorded and analyzed between 200 and 880 nm. The ignition time of the plasma isestimated. The expansion velocity of Si atoms in the plasma is measured.A mechanism ofthe N+ ion formation in the plasma is proposed to explain the appearance of N+ ions observedin the plasma. It was found by means of measuring the variation of the FWHM of Plasma's the emission line at different delay time that the electron density in the plasma decreases approximatively as an exponential of exp(-t1/2).