为了研究样品温度对激光诱导等离子体辐射特性的影响, 以国家标准土壤样品为靶, 在空气中利用波长为1 064 nm的Nd∶YAG纳秒脉冲激光烧蚀不同温度(≤350 ℃)下的片状样品, 测量了激光诱导等离子体的发射光谱强度和信噪比, 计算了光谱分析检出限和信号的测量准确度.实验结果表明, 当能量为200 mJ时, 随着样品温度的升高, 等离子体辐射逐渐增强, 并且在样品温度为300℃时达到最大值.计算表明, 元素Al、Mg、Ba和Fe在300 ℃样品温度时的光谱线强度比室温条件下分别提高了67%、58%、61%和52%, 信噪比分别增大了41%、51%、28%和38%, 且元素分析检出限和光谱信号稳定性均有改善.升高样品温度有利于改善激光光谱的质量.

In order to investigate the influence of sample temperature on the radiation characteristic of laser induced plasma, the target prepared from the national standard soil samples was ablated in air by a Nd∶YAG nanosecond pulse laser with wavelength 1 064 nm under different temperatures (TS≤350 ℃). The line intensity and signal-to-noise ratio of spectrum were measured, the detection limit of analytical spectroscopy and the accuracy of signal measurement were calculated. The experimental results show that, with the increase of sample temperature under the condition of laser energy for 200 mJ, plasma radiation increases and reaches the maximum at the sample temperature of 300 ℃. Calculations show that compared with that of the room temperature, the spectrum line intensities of Al, Mg, Ba and Fe increased by 67%, 58%, 61% and 52% respectively, and the spectral signal-to- noise ratios increased by 41%, 51%, 28% and 38% respectively. The detection limit of analytical elements and the stability of spectral signal were improved. Obviously, the rise of the sample temperature can effectively enhance the quality of the laser spectrum.