Laser-induced Plasma Spectroscopy using Infrared CO2 Laser and its Applications for Elemental Analysis

A review of a study on laser-induced plasma spectroscopy using a transversely excitedatmospheric (TEA) CO2 laser has been presented. This study was divided into two parts: the first partinvolves the shock wave plasma induced by a TEA CO2 laser, which is induced under a low-pressureambient gas at 1 Torr. The other part involves producing metal-assisted gas plasma under atmosphericpressure, induced by a transversely excited atmospheric CO2 laser. Time-resolved spatial distributionand plasma dynamics have been studied in detail using unique experiments. Furthermore, theshock wave model was also presented. Some applications of the shock wave plasma include highlysensitive analysis in solid samples and films attached to the substrate. The TEA CO2 laser-inducedgas plasma highlights numerous advantageous features, such as a high temperature of approximately7000 K, exceptional uniformity in the plasma density, a relatively low plasma density, and an exceptionallyhigh heat capacity. One of its applications is the direct analysis of powder samples. Furthermore,it is confirmed that the TEA CO2 laser bombardment produces a large number of He metastableatoms in the He gas plasma. The analytical emission exhibits distinct characteristics, includingnarrow spectral width, strong intensity, low background, and long lifetime. This, in turn, validates theexcitation process facilitated by helium metastable atoms. The novel applications of "selective detectionof H" in metal samples using TEA CO2 laser-induced He gas plasma have been emphasized.