Allotropes energy levels

C ulfuT exists in a variety of metastable molecular forms and polymorphs (I). For most of these allotropes the color is knovsoi well and is used often as an identifying tool. However, the spectrum of these species, with few exceptions, is not established well. This article reviews the spectra observed for polymeric sulfur, Sg, Sg, S4, S3, and S2 and discusses and predicts the electronic energy levels, the spectrum, and color of these and some other allotropes. 

This paper consists of five sections. In the first, the absorption spectrum of solid sulfur is discussed the second deals with liquid sulfur, the third reviews spectra of the vapor, and the fourth describes spectra of sulfur allotropes in solution, glasses, and matrices. The fifth section is a short review of some extended Huckel computations of energy levels of various allotropes in different structural configurations. 

Knowledge of electronic energy levels of sulfur allotropes is still rather meager. It is amazing that no great effort has been made to record and analyze the spectrum of Sg. For example, Sg must have a low lying triplet state in the visible. This triplet state is not known although its... 

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