The uv absorption spectra of <i>p</i>-dibromobenzenes-H<sub>4</sub> and −D<sub>4</sub> have been recorded on a Hilger E<sub>1</sub> large quartz spectrograph in the regions 35370–39540 cm<sup>−1</sup> and 35340–39470 cm<sup>−1</sup>, respectively. The assignments of vibronic bands have been made using the results from the two isotopic molecules. Some of the previous assignments have been revised in the light of the data from the present investigations.
J. V. Shukla, K. N. Upadhya, and S. N. Thakur, "The π-π* Electronic Absorption Spectra of p-Dibromobenzenes-D4 and -H4," Appl. Spectrosc. 25, 85-89 (1971)