Absorption of Bicycloheptane and Bicycloheptene in the Vacuum Ultraviolet

The vacuum ultraviolet absorption spectra of bicycloheptane and bicycloheptene have been investigated in the region from 45 000 to 65 000 cm—1. Two distinct band systems with maxima at 51 125 and 59 715 cm—1 were noted in the case of bicycloheptene, each with an oscillator strength of 0.15. The first observed absorption of bicycloheptane was near 55 000 cm—1 while that of the unsaturated hydrocarbon was displaced more than 8000 cm—1 toward lower frequencies. In both compounds, sharp narrow bands were superimposed on the continuous absorption. In a study of the photodecomposition, it was shown that cyclopentadiene and ethylene were formed as photodecomposition products of bicycloheptane and also of bicycloheptene.