The vacuum ultraviolet spectrum of the bromine molecule

Abstract

The absorption spectrum of bromine has been photographed in the first and higher orders of a 10.7-m. concave vacuum grating spectrograph in the region 1700-1170 Å .A number of band systems have been obtained in the region 1510-1170 Å , most of which correspond to Rydberg transitions. In addition, an extensive band system with closely-spaced bands degraded to longer wavelengths has been recorded in the region 1700-1500 Å . Among the Rydberg systems, five series have been found to converge to 85 165 ± 80 cm⁻¹ which represents the ionization potential of the molecule leading to the ²Π _3/2g state of the molecular ion. They arise due to transitions from the ground state to [σ _g²π _u⁴π _g³²Π_3/2g]npσ _u, [σ _g²π _u⁴π_g³²Π_3/2g]npπ _u, [σ _g²π _u⁴π _g³²Π_3/2g]nfσ _u, [σ _g²π _u⁴π _g³²Π_3/2g]nfπ _u, and [σ _g²π _u⁴π _g³²Π_3/2g]nfδ _u configurations where n takes the running values 5, 6, 7, - etc. The first few members of four similar series corresponding to the transitions to the states involving the [σ _g²π _u⁴π _g³²Π_1/2g] core have been identified and the ionization limit of these series is estimated to be at 88 306 ± 80 cm^-1. Two of the remaining band systems have been found to be very likely due to transitions to the Rydberg states with the configurations [σ _g²π _u³π _g⁴²Π_3/2u]5sσ _g and [σ _g²π _u³π _g⁴²Π_1/2u]5sσ _g, respectively. Three of the observed systems which do not involve Rydberg states appear to have for their upper levels the ¹Π_u(1_u), ³Π(1_u), and 3Π(0_u⁺) states arising from the configuration σ _gπ _u³π _g⁴σ _u².