微波辅助激光诱导击穿光谱对大米元素分析的实验研究

Elemental analysis of rice using microwave assisted-laser induced breakdown spectroscopy

利用Nd：YAG纳秒脉冲激光器输出的1 064nm波长强光束击打在大米样品表面,用2.45GHz型磁控管同轴输出微波装置对激光诱导产生的等离子体进行微波加热,结合激光诱导击穿光谱（LIBS）技术对大米中元素进行了初步检测研究。根据美国国家标准与技术研究院原子发射光谱数据库（NIST）,对大米中C、Mg、Ca、Si、Cd等元素在210~480nm波段内的特征谱线进行了标识和归属,通过对比传统LIBS和微波辅助LIBS（MA-LIBS）产生的等离子体信号光谱,发现MA-LIBS光谱强度增强效果明显,其最佳增强效果可达21倍多。这些结果对增强激光诱导等离子体的发光强度具有参考价值,也为提高LIBS技术探测灵敏度提供了一种全新的研究方法。

A new laser-induced breakdown spectroscopy （LIBS） enhancement method utilizing interaction between microwave radiation and laser-induced plasma is proposed to analyze the elements in rice. The laser induced plasma from the rice surface is generated by using a nanosecond pulsed 1064 nm beam of Nd： YAG laser irradiate the rice, and microwave radiation is generated by a magnetron at frequency of 2.45 GHz. The emission lines of the main elements in rice,such as carbon （C） ,magnesium （Mg） ,calci- um （Ca）,silicon （Si） and cadmium （Cd）,are identified according to the national institute of standards and technology database of atomic emission at waveband from 210 nm to 480 nm. It is found that the rel- ative intensities of the emission lines of microwave assisted-LIBS （MA-LIBS） are stronger than conventional LIBS by making a comparative analysis of the spectra of laser induced breakdown plasma and mi- crowave assisted-laser induced breakdown plasma. Up to 21 times enhancement on different spectral lines is achieved. The results in this paper have an important reference and significance for enhancing the intensities of LIBS emission, and provide a new way to improve the LIBS detection sensitivity.