Spectroscopic Studies in the Near Ultraviolet of the Three Isomeric Dimethylbenzene Vapors. I. Absorption and Fluorescence Spectra ofParahyphen;Dimethylbenzene

摘要

The absorption spectrum ofparahyphen;xylene between 2850 and 2350A was photographed using a 3hyphen;meter grating spectrograph, and the corresponding fluorescence spectrum between 3125 and 2720A was photographed with a Bausch and Lomb medium quartz spectrograph. The electronic transition involved is interpreted as1A1gmdash;1B3uwith the 0, 0 band at 36733 cmminus;1. Progressions in the fluorescence spectrum involve the totally symmetric vibrations 829 and 1208 cmminus;1, while progressions of the corresponding frequencies 775 and 1185 cmminus;1appear in the absorption spectrum. A weak portion of the spectrum is identified with a sohyphen;called forbidden transition involving the bgr;1ghyphen;component of the 606egr;g+benzene vibration. This bgr;1ghyphen;vibration has a frequency of 648 cmminus;1in the ground state and of 552 cmminus;1in the upper state. The agr;1ghyphen;component of the egr;g+benzene vibration inparahyphen;xylene has a lower state frequency of 458 cmminus;1and the upper state value of 367 cmminus;1. The Tesla luminescence spectrum is interpreted in relation to the fluorescence and absorption spectra.