Emission spectra of atomic and molecular nitrogen from photolysis of ammonia in solid neon

Abstract

Dilute samples of NH3 and ND3 in solid neon near 4 K were irradiated at 200 or 173 or 143 nm with light from a synchrotron. We recorded emission spectra of atomic N, involving states 4So, 2Po and 2Do, and of molecular N2, involving states X 1Σg+, A 3Σu+, B 3Πg and C 3Πu in systems with vibrational progressions in the lower states. The emission spectra covered the near-ultraviolet, visible and near-infrared regions from 200 to 1100 nm; the far-ultraviolet absorption spectrum for the precursor NH3 in solid neon was also measured. Recorded for samples in darkness after irradiation at 143 nm during warming from ∼5 K to ∼8 K, thermoluminescent spectra consisted mostly of lines emitted by molecular N2. The analysis of these spectra, and their temporal development, provides information about the nature of dissociative and trapping processes in solid neon under cryogenic conditions involving monochromatic synchrotron radiation.