铝合金中锌元素的高重频火花放电增强激光诱导击穿光谱高灵敏分析

锌元素的高灵敏分析在工业生产、冶金制造等领域中均具有非常重要的意义。而传统的激光诱导击穿光谱技术(LIBS)在测定固体样品中的锌元素时灵敏度相对较低。实验采用高重频火花放电增强激光诱导击穿光谱并结合锁相放大的微弱信号检测技术实现了铝合金中锌元素的高灵敏分析。在1kHz的重复频率下,以火花放电技术增强激光等离子体的光学辐射;以门控放大器选择放大锌的原子辐射信号并降低白光背景干扰;再采用锁相放大技术来实现对微弱原子辐射信号的高灵敏检测。基于标准样品在优化的实验条件下建立了铝合金样品中锌元素的校正曲线。锌的检出限达到了3.8μg/g,比采用传统的LIBS技术检测铝合金中锌元素时的检出限改善了一个数量级。方法有助于实现合金中锌和其他元素直接的和高灵敏的定量分析,在冶金分析领域有较好的应用价值。

Highly sensitive zinc analysis for aluminum alloy with high repetition rate spark-discharge enhanced laser-induced breakdown spectroscopy

Highly sensitive zinc analysis was necessary and important in different fields, such as industrial production, metallurgical manufacturing and so on. Conventional laser-induced breakdown spectroscopy (LIBS) had relatively low analytical sensitivity in the determination of zinc elements in solid samples. High repetition rate spark-discharge enhanced laser-induced breakdown spectroscopy combined with weak signal detection with lock-in amplifier was developed to realize highly sensitive zinc analysis for aluminum alloy samples. Experimentally operated under 1 kHz pulse repetition rate, the optical radiation of laser-induced plasma was enhanced by spark-discharge; the zinc atomic emission signal was selectively amplified and the continuum background of the plasma radiation was rejected by a gated pre-amplifier; finally a lock-in amplifier was used to realize highly sensitive detection of weak atomic emission signal. Based on the standard samples, a calibration curve of zinc in aluminum alloy samples was established under currently optimized experimental conditions. The limit of detection for zinc reached 3.8μg/g, which was an order better than those obtained by traditional LIBS in analysis of zinc in aluminum alloy. This technology was helpful to realize direct and highly sensitive quantitative analysis of zinc and other elements in alloy samples, and could be well applied in the field of metallurgical analysis.