The dynamics of chlorine and hydrogen atom formation in the 193.3 nm gas-phase laser photolysis of room-temperature 1,1-dichloro-1-fluoroethane, CH3CFCl2 (HCFC-141b), were studied by means of the pulsed-laser-photolysis and laser-induced fluorescence (LIF) "pump-and-probe" technique. Nascent ground-state Cl(P-2(3/2)) and spin-orbit excited Cl*(P-2(1/2)) as well as H(S-2) atom photofragments were detected under collision-free conditions by pulsed Doppler-resolved laser-induced fluorescence measurements employing narrow-band vacuum ultraviolet probe laser radiation, generated via resonant third-order sum-difference frequency conversion of dye laser radiation in krypton. Using HCl photolysis as a reference source of well-defined Cl(P-2(3/2)), Cl*(P-2(1/2)), and H atom concentrations, values for the chlorine-atom spin-orbit branching ratio [Cl*]/[Cl]=0.36+/-0.08, the total chlorine atom quantum yield (Phi(Cl+Cl)*=1.01+/-0.14), and the H atom quantum yield (Phi(H)=0.04/-0.01) were determined by means of a photolytic calibration method. From the measured Cl and Cl* atom Doppler profiles the mean relative translational energy of the chlorine fragments could be determined to be E-T(Cl)=157+/-12 kJ/mol and E-T(Cl*)=165+/-12 kJ/mol. The corresponding average values 0.56 and 0.62 of the fraction of total available energy channeled into CH3CFCl+Cl/Cl-* product translational energy were found to lie between the limiting values 0.36 and 0.85 predicted by a soft impulsive and a rigid rotor model of the CH3CFCl2-->CH3CFCl+Cl/Cl-* dissociation processes, respectively. The measured total chlorine atom quantum yield along with the rather small H atom quantum yield as well as the observed energy disposal indicates that direct C-Cl bond cleavage is the most important primary fragmentation mechanism for CH3CFCl2 after photoexcitation in the first absorption band. (C) 2003 American Institute of Physics.