A theoretical and experimental study of the HPCl radical: the (A)over-tilde(2)A ' -> (X)over-tilde(2)A '' visible emission spectrum

We report the first observation of the (A) over tilde (2)A' --> (X) over ti lde (2)A " visible emission spectrum of HPCl. The spectrum shows a series o f blue-degraded bands with two prominent progressions in the ground state b ending vibration. Ab initio calculations are used to help to assign the obs erved spectrum. The experimentally derived constants are T-0 = 21 305 cm(-1 ), omega (2)" = 868 cm(-1) omega (2)' = 622 cm(-1) and omega (3)' = 529 cm( -1) compared with calculated values of T-0 = 23 518 cm(-1), omega (2)" = 89 3 cm(-1) omega (2)' = 670; cm(-1) and omega (3)' = 524 cm(-1). The bending progression results from a substantial change in the bond angle between the ground and electronically excited states from 96 degrees to 118 degrees. ( C) 2000 Elsevier Science B.V. All rights reserved.