De-excitation of the Ar 3P2, 3P1, and 1P1 states in pure argon and in Ar/H2 or Ar/CO mixtures

Publisher Website
Google Scholar
Abstract
The de‐excitation of the 3P2, 3P1, and 1P1 states of argon was studied in pure argon between 10 and 200 torr and in Ar+CO and Ar+H2 mixtures. These states, which were followed by absorption spectroscopy, are populated after excitation of the gas by a short (20 ns) pulse of 500 keV electrons. The three body rate constants k2, which were not considered in previous low pressure studies, were measured for the two resonant states 3P1(k2=1.7×10−32 cm6 s−1) and 1P1 (k2=0.9×10−32 cm6 s−1). For the metastable 3P2, the measured value of k2 (1.6×10−32 cm6 s−1) is in good agreement with those found in the literature. However, our two body rate constant k1 for the 3P2 state is about ten times higher than values obtained previously from low pressure measurements. The rate constants for the quenching by CO and H2 were measured for the metastable state 3P2 (1.85 and 10.5×10−11 cm3 s−1) and for the resonant states 3P1 (4.5 and 20×10−11 cm3 s−1) and 1P1 (8.5 and 33×10−11 cm3 s−1).