Effect Of Temperature On Femtosecond Laser-induced Breakdown Spectroscopy

Laser spectrum technology becomes an important tool in the elemental analysis, which has features: less destructive, high-resolution and can be of solid, liquid, gas and aerosol materials for real-time analysis. Laser-induced breakdown spectroscopy(LIBS) is such a kind of technology. In comparison with other optical methods, such as laser spectroscopy technology, laser Raman spectroscopy technology, laser absorption spectroscopy technology, etc, experiment method of LIBS is simple, and that can overcome the multielement analysis at the same time. Further, the technique has features like fast analysis, high sensitivity, and is implemented in multicomponent, in situ, online, real-time, trace detection under hostile environmental or remote telemetry conditions. Therefore the technology is widely used in different fields such as biomedical detection, soil testing, metallurgical field, detection of toxic materials, medical testing, ideal for analysis of irreplaceable works of art and archaeological artifacts.With the progress of laser technology, scientific research workers focus on femtosecond laser, which leads to the rapid development of the femtosecond laser induced breakdown spectroscopy(femosecond-LIBS) with ultrashort pulse width and smaller continuous radiation intensity. In addition, the femtosecond laser has lower threshold, high stability and repeatability. Therefore, we adopt a series of experimental research of femtosecond laser that can improve the detection accuracy and detection limit.This article mainly introduces laser induced breakdown spectroscopy from four chapters. The first chapter introduces the developing history of laser induced breakdown spectroscopy and compares the advantages and disadvantages of LIBS with traditional analysis methods. The application of LIBS is introduced in many fields, which fully appears the significance and value of LIBS in the modern society. Then we introduce the femtosecond laser induced breakdown spectroscopy and its application in the production and life, which makes us further understanding for femtosecond laser technology. The second chapter describes the basic theory of laser induced breakdown spectroscopy in detail, then plasma are introduced from different aspects, including the concept, characteristics and applications of plasma and we emphasize the process of laser induced plasma spectrum. It also expounds the model of laser induced plasma and line broadening mechanism as well as the method of calculating the plasma temperature. The third chapter is the experimental section of this paper. First, we introduce the experimental devices and working principle of the system; Secondly, we select the experimental research object and the spectral line under testing; Finally, the intensity of the plasma emission line generated by laser from three aspects is discussed, we observe the change of the spectral line intensity by changing the sample temperature, laser pulse energy and the delay time. The experimental results show that the higher sample temperature can improve the emission intensity of the spectrum, increasing the pulse energy can also make the spectral line intensity stronger, and spectral line intensity increases with the increasing of the delay time.But when the laser pulse energy and delay time reach a certain value, the spectral line intensity no longer increases. The fourth chapter summarizes the experimental research results and the significance of this paper, which puts forward the problems existing in the experiment, and the next research direction is determined.