Analysis of autoionizing Rydberg states in the vacuum ultraviolet absorption spectrum of HBr and DBr
The photographic absorption spectrum of HBr and DBr above the first ionization limit (800-1000 Å) has been analyzed. No analyzable rotational structure was observed, indicating that the autoionization rate is faster than the rotational period. Two Rydberg series converging to the second ionization limit ( 2Σ +) have been identified, one with n ∗ = 2.75, 3.74, ⋯,14.7 , and the other with n ∗ = 2.35, 3.38 . The symmetries cannot be determined conclusively, but the most probable assignment for the first series is 4pσ 4pπ 4nsσ ( 1Σ+) n = 6, 7, ⋯, 18 , and for the second, 4 pσ 4 pπ· npσ and/or npπ[ 1Σ+, 1Π] n = 5, 6 . Assuming that the intensity maxima assigned are band origins of vibronic states, a new ionization limit can be determined for HBr +( 2Σ+): T 0 = 123 373 ± 20 cm-1.