DOPPLER SPECTROSCOPY OF OH FRAGMENTS FROM THE PHOTODISSOCIATION OF HOCL AT 266 AND 355 NM

Photofragment Doppler spectroscopy has been used to characterize the e lectronically excited states of HOCl in the ultraviolet region. In the photolysis of HOCl, the Doppler profile of the nascent OH fragments s hows a marked difference in the recoil anisotropy parameters: beta = 1 .31 +/- 0.12 at 266 nm and -0.70 +/- 0.12 at 355 nm. Photoabsorption a t 266 nm is characterized by the transition moment predominantly paral lel to the O-Cl axis, which is consistent with assignment of the stron g band at 250 nm to the 2(1)A'-1(1)A' transition. On the other hand, t he transition moment at 355 nm is perpendicular to the O-Cl-bond. The measurement of the rotational alignment also shows the transition mome nt to be perpendicular to the molecular plane at 355 nm, indicating th e existence of the 1(1)A '' <-- 1(1)A' transition above 300 nm.