Velocity map ion imaging of H atoms from the dissociation of HCO () using Doppler-free multi-photon ionization

Velocity map ion imaging using Doppler-free 2+1 multi-photon ionization at λ = 243.1 nm has been applied to monitor the nascent H atoms from the predissociation of HCO ( A ∼ 2 A ″ ) in the (0, 0, 101) vibrational state. Employing two balanced, counterpropagating circularly (σ+ and σ−) polarized probe beams, complete velocity map images were accumulated with every laser shot without having to scan the probe wavelength over the strongly Doppler-broadened line profile. The H–CO bond dissociation energy, CO internal energy distribution, and anisotropy parameter are presented and compared with literature data.