Re-evaluation of the hyperfine coupling constants forB−Xtransitions inI2

Abstract

High-precision measurements of the ${\mathrm{I}}_2$ $B-X(43,0)\mathrm{}$ $R\mathrm{}\left(15\right)\mathrm{}$ hyperfine spectrum are reported. The $R\mathrm{}\left(15\right)\mathrm{}$ and previously measured (43,0) $P\left(13\right)\mathrm{}$ spectra were fitted to 2.6 and 5.4 kHz, respectively. A previous fit of the $P\left(13\right)\mathrm{}$ which resulted in a nonzero value for the magnetic octupole coupling constant was apparently in error. Extension of such measurements to other rotational vibrational levels in ${\mathrm{I}}_2$ using an optically pumped laser and two-step excitation is discussed.