Highly resolved detection of deuterium at atmospheric pressure

Abstract

A highly resolved analytical method suitable for the analysis of emission spectra from hydrogen atoms and deuterium atoms is presented. The method is based on microwave-assisted laser-induced breakdown spectroscopy and is applicable to liquid phase analytes under atmospheric conditions. Emissions from excited hydrogen (and deuterium) atoms and OH (and OD) radicals were collected and quantitatively analysed using two types of diffraction gratings. The method takes advantage of the reduced electron density in microwave-assisted laser-induced breakdown spectroscopy plasma, which produces a narrow atomic emission linewidth. This feature permits highly resolved spectra of 0.2 volume fraction of deuterium in the presence of 0.8 volume fraction of hydrogen. Using a 2400 lines per mm diffraction grating and D_α emission, the MW-LIBS deuterium limit of detection and limit of quantification were 0.4% and 1.3%, respectively. Using a 2400 lines per mm diffraction grating and OD radicals' emission, the MW-LIBS limit of detection and limit of quantification were 0.85% and 2.8%, respectively. The OD rotational branches were resolved even better using a 3600 lines per mm diffraction grating, yielding a three-fold improvement in the limit of detection. The detection of hydrogen atoms and deuterium atoms based on MW-LIBS is very beneficial due to its excellent repeatability, selectivity, and applicability under atmospheric pressure in ambient air.