Spectral emission of fractional-principal-quantum-energy-level atomic and molecular hydrogen

Abstract

Extreme ultraviolet (EUV) spectroscopy was recorded on microwave discharges of helium with 2% hydrogen. Novel emission lines were observed with energies of q×13.6 eV where q=1,2,3,4,6,7,8,9,11 or these discrete energies less 21.2 eV corresponding to inelastic scattering of these photons by helium atoms due to excitation of He (1s 2) to He (1s 12p 1). These lines matched H(1/ p), fractional Rydberg states of atomic hydrogen, formed by a resonant nonradiative energy transfer to He +. Corresponding emission due to the reaction 2H(1/2)→H 2(1/2) with vibronic coupling at E D+ vib =p 2E D H 2 ±(υ ∗/3)E vib H 2(υ=0→υ=1) , υ ∗=1,2,3,… was observed at the longer wavelengths for υ ∗=2 to υ ∗=32 and at the shorter wavelengths for υ ∗=1 to υ ∗=16 where E D H 2 and E vib H 2(υ=0→υ=1) are the experimental bond and vibrational energies of H 2, respectively. Similar emission due to Ne + with hydrogen was also observed, and the exothermic reaction was confirmed by the observation of 306±5 W of excess power generated in 45 cm 3 by a compound-hollow-cathode-glow discharge of a neon–hydrogen (99%/1%) mixture corresponding to a power density of 6.8 MW/m 3 and an energy balance of about −5×10 5 kJ/(mol H 2) compared to the enthalpy of combustion of hydrogen of −241.8 kJ/(mol H 2).