Photodissociation dynamics of HCOOH(Ã)

The technique of Doppler-resolved, polarised LIF spectroscopy has been employed in a study of the energy and momenta disposal in the OH fragments generated via photodissociation of HCOOH (Ã ¹A″) at 225 nm. The majority of the excess energy resides in fragment translation (≈ 78%) and internal excitation of the HCO fragment (≈ 12%). An analysis of the Doppler-resolved profiles reveals that OH rotational excitation (for N″ ≈ 6) is generated primarily by out-of-plane C-OH torsional motion in the excited parent molecule. The results are compared with those for the OH fragments generated via photodissociation of the iso-electronic molecule HONO(Ã ¹A″).