Ion-Velocity Map Imaging Study of Photodissociation Dynamics of Acetaldehyde

The photodissociation dynamics of acetaldehyde in the radical channel CH3+FICO has been reinvestigated using time-sliced velocity map imaging technique in the photolysis wavelength range of 275-321 nm. The CH3 fragments have been probed via (2+1) resonance-enhanced multiphoton ionization. Images are measured for CH3 formed in the ground and excited states (v(2)=0 and 1) of the umbrella vibrational mode. For acetaldehyde dissociation on T-1 state after intersystem crossing from S-1 state, the products are formed with high translational energy release and low internal excitation. The rotational and vibrational energy of both fragments increases with increasing photodissociation energy. The triplet barrier height is estimated at 3.881 +/- 0.006 eV above the ground state of acetaldehyde