Two-dimensional (2Â +Â n) REMPI of HCl: Observation and characterisation of a new Rydberg state

Two-dimensional REMPI data, obtained by recording ion mass spectra for HCl as a function of two-photon wavenumber, revealed a previously unobserved (2 + n) REMPI spectra for H35Cl and H37Cl with band origin for H35Cl at 82 521.2 cm−1. Analysis of the data, involving simulation calculations, relative ion-yield determinations laser-power-dependence measurements and comparison with earlier experimental and theoretical work allowed the upper state to be assigned as the g3Σ+(1), v′ = 0 Rydberg state with B0′ = 10.26 cm−1 for H35Cl.