15min:
IMPROVEMENT OF SPECTROSCOPIC CONSTANTS FOR THE A3 Pi1u leftarrow X1 Sigma+g SYSTEM OF Br2.

NOBUO NISHIMIYA, TOKIO YUKIYA AND MASAO SUZUKI, Department of Electronics and Information Technology, Tokyo Polytechnic University, Iiyama 1583, Atsugi-City, 243-0297 Kanagawa, Japan; ROBERT J. LE ROY, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

High-resolution spectroscopy in the near infrared region is very important for frequency standards. We have measured the Doppler limited vibrational-rotational spectrum of ICl, IBr, I2 and Br2 by using a titanium sapphire laser, and have reported their spectroscopic constants. The present work presents revised spectroscopic constants for the X-state of Br2 which are obtained by performing a combined-isotopologue least-squares fit to all available data for the three isotopic species. We are also attempting to observe the lowest vibrational levels of the A-state in order to allow us to determine the potential energy function of this state. Measurements were made at room temperature in the region 13000-13700~ cm-1 and at 150-250oC in the region 11600-13000~ cm-1. Details of these results will be presented.