Some notes on the role of meta-stable excited state of helium atom in laser-induced helium gas breakdown spectroscopy

Investigation of helium addition for laser-induced plasma spectroscopy of pure gas phase systems: Analyte interactions and signal enhancement

“…The recent work by Kurniawan and co-workers has specifically addressed this issue for hydrogen analysis via LIBS [20][21][22][23][24]. Similar to the current results, they observed an increase in hydrogen emission intensities combined with a decrease in hydrogen line broadening with helium addition, in which the latter may be interpreted as a decrease in electron density although no direct electron density calculations were reported.…”

“…However, it is worth noting that for cases of very low analyte concentrations in a helium balance, it is possible that metastable state helium atoms play a role in enhancement of analyte emission [24]. This is due to the fact that at very low analyte concentrations in a high helium balance, metastable helium has a significant population density, as observed in the present study (see Fig.…”

“…Helium was found to produce the optimal signal-to-noise ratio in comparison to air and argon, and resulted in reduced line broadening. Contemporary studies by Kurniawan and co-workers have specifically addressed the role of helium for enhancement of hydrogen analysis in solid samples, including zircaloy-4 alloys, via the LIBS technique [20][21][22][23][24]. In their studies, hydrogen emission intensities were enhanced while Stark broadening was reduced through the use of helium breakdown, using both single and double-laser LIBS methodologies.…”

Time-resolved optical emission spectroscopic measurements of He plasma induced by a high-power CO2 pulsed laser

“…Because of the transient characteristics of the plasma plume created by LIB, the optical emission spectroscopy (OES) technique with time and space resolution is especially appropriate to obtain information about the behavior of the formed species as well as to study the dynamics of the plasma expansion. The temporally-resolved LIB technique in He has been used by several researchers [7][8][9][10][11][12][13] using high-power lasers. The emission spectra of LIB plasma produced by a CO 2 laser in different gases have been reported recently by us [14][15][16].…”

Characteristic emission enhancement in the atmosphere with Rn trace using metal assisted LIBS

“…Furthermore, the effect of helium for the enhancement of hydrogen signals in zircaloy-4 alloys, has been extensively addressed. [32][33][34][35][36] Helium is added for the signal enhancement in LIBS such that the analysis of pure gaseous systems has been performed using carbon and hydrogen atomic emission lines. 37,38 Resonance-enhanced laser induced plasma spectroscopy (RELIPS) is another mechanism that was extensively studied in manometric and atmospheric rare gases such as Ar and Xe, using tunable dye laser.…”