激光诱导黄铜中Zn等离子体光谱的时间演化特性

在常温常压下, 利用自建的激光诱导击穿光谱（LIBS）实验装置获得纳秒激光诱导黄铜等离子体光谱, 研究发射光谱中Zn等离子体光谱在增强型光电耦合器件（ICCD）门延迟为150~3 000 ns时的演化规律, 并利用Stark展宽系数及能级跃迁参数计算等离子体的电子温度和电子密度随ICCD门延迟的演化规律. 实验结果表明: 当ICCD门延迟为150~500 ns时, 初始阶段光谱呈较强的连续谱, 随着ICCD门延迟的增大, 在连续谱上逐渐凸显Zn原子的线状特征谱线, 特征谱线强度在ICCD门延迟为500 ns时达最大; 继续增大ICCD门延迟, 谱线强度逐渐减小, 当ICCD门延迟为3 000 ns时, 等离子体的特征谱线信号基本消失; 谱线强度和电子温度随ICCD门延迟的变化一致, 电子密度和ZnⅠ(481.0 nm)谱线的半高宽随ICCD的变化接近指数拟合.

Time Evolution Characteristics of Zn Plasma Spectra in Brass Induced by Laser

The nanosecond laser induced brass plasma spectra were obtained by using a self built laser induced breakdown spectroscopy (LIBS) experimental device at room temperature and atmospheric pressure. We studied the evolution of the Zn plasma spectrum in the emission spectrum with 150—3 000 ns gate delay of the intensified charge coupled device (ICCD), and calculated the evolution law of electron temperature and electron density of the plasma with ICCD gate delay by using the Stark broadening coefficient and energy level transition parameters. The experimental results show that when the ICCD gate delay is 150—500 ns, the spectrum shows a strong continuous spectrum at the initial stage. With the increase of ICCD gate delay, the linear characteristic lines of Zn atoms are gradually highlighted on the continuous spectrum. The spectral intensity of the characteristic line reaches maximum when the ICCD gate delay is 500 ns. With the increase of the ICCD gate delay, the spectral intensity gradually decreases, and the characteristic line signal of the plasma disappears when the ICCD gate delay is 3 000 ns. The spectral intensity and electron temperature are consistent with the change of ICCD gate delay, the electron density and the full width half maximum (FWHM) of ZnⅠ(481.0 nm) spectral line is close to exponential fitting with the change of ICCD.