Disentangling the H2 E, F(1Σ g +) (v′=0−18)←X(1Σ g +)(v″=3−9)(2+1) REMPI spectrum via 2D velocity-mapped imaging

Abstract

We have measured the two-photon Resonance-Enhanced Multiphoton Ionization (REMPI) spectrum of H by producing the hydrogen molecule via photolysis of HCO. H is produced with rovibrational energies up to 30,000 cm, at a maximum observed of (9,5). In the well-resolved jet-cooled HCO spectrum, ortho and para H are selectively produced with near 100% selectivity. Over 470 REMPI transitions were identified in the EF−X band system, many of which have not been seen previously, including transitions to EF levels not yet accurately measured. Speed distributions were obtained for each REMPI transition using Velocity-mapped imaging, aiding in the assignment by providing a precise measurement of the internal energy of the H molecule.