Spectroscopy of the CH3O A 2A1–X 2E system by laser-excited fluorescence method

Abstract

Laser‐excitation spectra and single vibronic level fluorescence spectra of CH₃O and CD₃O A ²A₁–X ²E transitions are reported. The spectral origin of the excitation spectrum is at 31 540 cm⁻¹ (317.06 nm); extensive progressions in the stretching mode ν₃′ (678 cm⁻¹ for CH₃O and 655 cm⁻¹ for CD₃O) dominate the spectra. Fluorescence bands appear that are assigned as the transition to the C–O stretching mode and CH₃ deformation modes, giving ν₃^″=1015 cm⁻¹ for CH₃O and 1010 cm⁻¹ for CD₃O. Measured vibronic band intensities agree well with the Franck–Condon calculation. The band shape is well reconstructed on the assumption of SCF calculated geometry. No predissociation occurs below 35 900 cm⁻¹.