15min:
IR-MICROWAVE DOUBLE RESONANCE STUDIES OF DIPOLE MOMENTS IN THE nu1 and nu3 STATES OF AMMONIA.

MARK D. MARSHALL, Department of Chemistry-2243, Amherst College, P.O. Box 5000, Amherst, MA 01002-5000; KAMIL CAN IZGI AND J. S. MUENTER, Department of Chemistry, University of Rochester, Rochester, NY 14627.

Infrared laser-microwave double resonance spectroscopy is used to observe the Stark effect of tunneling transitions within the nu1 and nu3 hydrogen stretching states of \chemNH3. Dipole moments for 11 J,K states of nu1 and 3 J,K states of nu3 are measured to high accuracy. These data, combined with previous measurements in the ground and excited bending states, give a dipole moment function of: µ_v1 v2 v3 v4 = 1.5610 + 7.2 × 10-3 (v1 + \textstyle1 \over 2 ) - 2.271 × 10-1 (v2 + \textstyle1 \over 2 ) + 3.75 × 10-2 (v3 + 1 ) - 1.65 × 10-2 (v4 + 1 ) . µe = 1.561 D is the first experimental measurement of the \chemNH3 equilibrium moment. These results are also used to analyze and recalculate the dipole moment measured by Shimizu and coworkers in a vNH = 5 excited state of \chemNH3.