3 + 1 Resonance enhanced multiphoton ionisation spectroscopy of HBr†
Abstract
This
paper extends the knowledge of highly excited Rydberg states of HBr by presenting detailed measurements of the 3 + 1 resonance enhanced multiphoton ionisation (′
= 0) and 5 as new members of vibrational progressions
(
′≠0) originating from the promotion of a π electron into a σ, π or δ Rydberg orbital and correlating with the
ground X2Π state of the HBr+ ion core. Symmetry assignments in terms of either (Λ, S) or (Ω, ω) coupling schemes for the various
identified excited states are offered, based on band contour simulation and quantum defect considerations.
The main result of the present work is the observation of new states and bands involving vibrationally
excited levels which were not accessible in previous one and two-colour
′
= 0 and 1 levels of the L1Φ3 state arising from the dδ Rydberg manifold,
as well as three other Ω
= 3 states within the dπ and dδ series which are reported here for
the first time.