10min:
THE C2N2 C1Bu - X1Sigmag+ TRANSITION: ASSIGNMENT OF THE EXCITED ELECTRONIC STATE, ITS ORIGIN AND VIBRATIONAL FREQUENCIES.

JOSHUA B. HALPERN AND YUHUI HUANG, DEPARTMENT OF CHEMISTRY, HOWARD UNIVERSITY, WASHINGTON, DC 20059.

A new analysis is presented for the VUV C2N2 C1Bu - X1Sigmag+ transition. Contrary to previous studies this is shown to be a linear to bent transition with a trans-bent C1Bu excited electronic state. The electronic origin is at 59,848 cm-1, about 550 cm-1 lower than previously thought . Vibrational bands between 170 and 145 nm are assigned. The C1Bu symmetric CN stretching frequency, nu1, is as previously noted 2050 \b+ 20 cm-1. It has been possible to assign four of the five other vibrational frequencies. The symmetric CC stretching frequency, nu2, is 926 \b+ 20 cm-1. The trans-bending vibrational frequency, nu3, is 532 \b+ 10 cm-1, the torsional bending frequency, nu4, is 110 \b+ 10 cm-1 and the cis bending frequency, nu6, is 140 \b+ 10 cm-1. Anharmonicities have also been determined for the various vibrational modes.