Features of VUV emission from plasmas generated by nanosecond laser pulses in air

Temporally-integrated characteristics of vacuum ultraviolet (VUV) plasma emission induced onto a steel target by 1064 nm laser radiation are investigated by spatially-resolved emission spectroscopy in air atmosphere. Emissions from the C (III) spectral line at 97.7 nm are recorded under the influence of several experimental parameters and conditions. These include laser wavelength, laser pulse energy, spatial distribution of emitting species as well as entrance slit-width of the spectrometric system. The overall objective of the work is to improve the detection capability of the laser-induced breakdown spectroscopy (LIBS) technique in the VUV regime. We also outline the role of LIBS in the field of elemental composition analysis of solid materials, and briefly describe its fundamental principles. The results obtained demonstrate a set of optimum conditions for maximum spectral line intensities and signal-to-background ratios of laser-generated plasmas in the VUV region. Moreover, in general, the emission characteristics of the vacuum ultraviolet-based spectra were similar to those previously investigated in the UV-visible spectral range.