THE VISIBLE BANDS OF s-TETRAZINE

Abstract

The $^{1}B_{3u}\leftarrow ^{1}A_{g} (\pi^{\ast}\leftarrow_{n})$ system of s-tetrazine, $H_{2}C_{2}N_{4}$, has been photographed at high resolution for the normal species and various isotopically substituted species. Rotational analyses have been carried out on bands of all the isotopic molecules studied, and have shown that the structure of the molecule in the gas phase differs somewhat from that reported in x-ray crystallographic studies. Most of the ground state vibrational frequencies have been determined, with the help of a reinvestigation of the infrared spectrum of the vapour at long path lengths, and several of the upper state frequencies have been assigned. The effect of electronic excitation on the geometric structure will be discussed.