ИСТИНА

Molecules present and emit in laser-induced plasma. Currently the molecules are used in LIBS for study of isotopic composition (boron, oxygen, etc). The molecular emission seems to be the most appropriate one for the halogen detection. Besides the analytical application molecules in laser-induced plasma can be useful for plasma diagnostics at later time or for the organic matrices. The other motivation for the use of molecular emission is the interpretation of meteor spectra. Since the temperature of nanosecond laser-induced plasma is close to those of plasma during meteor ablation, laser plasma can be used for model laboratory experiments. In this study we present the results of the use of molecular emission for analytical LIBS, plasma characterization and the simulation of meteor spectra. Methods. We used Q-switched Nd:YAG laser for plasma ignition in air and Czerny-Turner spectrometer with ICCD camera. We used both atomic and molecular emission for temperature calculation (with the use of Boltzmann plot and model and experimental fitting), and electron density calculation by Stark broadened lines. Results and discussions. We compared the metrological characteristics of double-pulse LIBS determination of chlorine in concrete by atomic line Cl I 837.59 nm line and single-pulse LIBS for those with the use of the CaCl bands. The advantages of the molecular bands are related to a sufficiently high excitation potential chlorine line, and a low degree of its atomization in plume. The the later times observation of CaCl emission significantly improved the sensitivity (LOD < 100 ppm). The molecules were also useful for temperature evaluation for LIBS of zooplankton by CN bands. This allows calibration-free determination of Li/Na, and Li/K ratios. The temperature dependent electronic spectra of diatomic molecules is necessary for possible assessment of the molecular composition of cosmic bodies, but ab initio calculations of electronic spectra of the very important FeO is extremely complicated. At the same time the evolution of the FeO intensity in laser plasma can provide such information. We prove the adequacy of such experiment by comparison of experimental and synthetic spectra generated in approximation of homogeneous plasma in LTE for a well studied AlO molecule.