Rotations and local modes in stannane, 116SnH4: Photoacoustic overtone spectra with a titanium:sapphire ring laser

Abstract

The fifth and the seventh stretching vibrational overtone bands of a monoisotopic stannane sample, 116SnH4, have been recorded with Doppler limited resolution using intracavity photoacoustic technique with a titanium:sapphire ring laser. Both band systems resemble closely symmetric top parallel bands in agreement with local mode predictions. The rotational fine structures of these bands have been analyzed with the symmetric top energy level formula and with a spherical top Hamiltonian which treats the problems as interacting rotational levels of A1 and F2 vibrations. Altogether about 200 vibration–rotation transitions have been assigned for both band systems. The fifth overtone band system shows some minor local perturbations due to interactions with bending states. The seventh overtone band is completely unperturbed. The observed vibration–rotation parameters are in good agreement with the ones calculated from a simple vibrational model.