The ultraviolet photodissociation of DCl: H/D isotope effects on the Cl(2P) atom spin-orbit branching

The photodissociation of jet-cooled DCI molecules subsequent to excitation in the long-wavelength tail of the first UV absorption band (A(1)II(1) <-- X(1)Sigma(+)) has been investigated at five wavelengths in the range 200-220 nm. Ground state C1(P-2(3/2)) and spin-orbit excited C1*(P-2(1/2)) photofragments were monitored using (2 + 1) resonance enhanced multiphoton ionization in a time-of-flight mass spectrometer. The product branching fractions are reported and compared with previous experimental results and high-level quantum mechanical calculations for HCI and DCl. A significant H/D isotope effect in the branching fractions is found at all the studied wavelengths, in quantitative agreement with recent theoretical predictions. (C) 1999 Elsevier Science B.V. All rights reserved.