Knowledge Bank

The electronic spectra of trans-1,3-butadiene and its 1,1,4,4-$d4$ and $d6$ isomers have been recorded and analyzed from 2300 - 1300 {\AA}. Four Rydberg series ($\delta$ = 0.087, 0.21, 0.42, and 0.67) composed of 3-10 members each and one symmetry ``forbidden” non-Rydberg transition were identified. One continuum was observed underlying the assorted discrete transitions. A comparison of the present analysis with those in the $literature1$ suggests that several prominent and weak spectral features of trans-1,3-butadiene have been misidentified.