MOLECULAR-HYDROGEN EMISSION IN THE VACUUM-ULTRAVIOLET FROM AN INDUCTIVELY-COUPLED PLASMA

Vacuum ultraviolet radiation is observed through a sampling orifice in a metal cone inserted directly into an Ar inductively coupled plasma (ICP). The many-lined spectrum of the H-2 Lyman bands is observed from an argon ICP with either H-2 gas or nebulized water added. The most p rominent bands are from the upsilon = 3, 4, 5 or 6 vibrational levels of the B (1) Sigma(u)(+) electronic state of H-2. The energies of the upsilon = 3, 4 and 5 levels are close to those of the Ar metastable le vels and of photons from the Ar resonance lines (11.5 to 11.8 eV). The se H-2 levels are probably populated at least in part by selective ene rgy transfer reactions between Ar metastable atoms and H-2 and/or by a bsorption of Ar resonance photons by H-2. The H-2 emission emanates on ly from the upstream reaches of the axial channel, i.e. the part of th e axial channel that is inside the load coil and induction region.