Rotationally resolved resonance scattering from a predissociating molecule: Ammonia-d3 excited at 2139 Å and 2144 Å

Abstract

Rotationally resolved resonance scattering spectra of ND₃ excited within the 0000←00⁺00 and 0100←01⁻00 bands of the ?←? transition have been photographed. The quantum yield of this emission has been measured (1×0.5×10⁻⁵) and is in agreement with that predicted for simple ’’fluorescence.’’ However, the spectra show evidence for excitation of rovibronic levels up to 20 cm⁻¹ off of resonance with the exciting line, and rotational lines within a single vibrational band obey ’’Raman’’ selection rules. Thus the position of rotational lines gives information about ground state energy levels only. Information about excited state energy levels is contained in the relative intensity of vibrational progressions in the emission spectra.