Terahertz Vibration−Rotation-Tunneling Spectroscopy of the Ammonia Dimer: Characterization of an out of Plane Vibration

Terahertz Vibration−Rotation−Tunneling Spectroscopy of the Ammonia Dimer. II. A−E States of an Out-of-Plane Vibration and an In-Plane Vibration

Terahertz vibration-rotation-tunneling transitions have been measured between ca. 78.5 and 91.9 cm-1, and assigned to A-E (ortho-para) combinations of NH3 monomer states. The spectrum is complicated by inversion splittings that correlate to E symmetry monomer rovibronic states. Twenty progressions have been assigned to six excited states involving an out-of-plane vibration and an in-plane intermolecular vibration. The quality of the fit was affected by strong Coriolis interactions among these states and possibly an additional K = 2 state that was not explicitly observed in the data.