A resonance Raman (RR) spectrum of NH3 excited by 212.8-nm radiation (fifth harmonic of Nd: YAG) has been obtained. This frequency is in resonance with the v′ = 1 level of the X → A absorption band. High-quality RR spectra are observed even though the A state dissociates with near unity quantum yield. Direct spectral evidence is found for N-H stretching (v1) Franck-Condon activity in the resonant absorption and the excited-state geometry is seen to be planar (D3h). Resonance-enhanced rovibrational Raman structure is observed. The resonant emission is determined to be RR scattering and not resonance fluorescence by line-shape analysis. New bending (inversion) levels of the ground state are identified. Moderate success in fitting the observed RR intensities is found by using one-dimensional bending Franck-Condon factors.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry