ABSTRACT
This chapter covers photochemical studies of three-and four-membered ring compounds isolated in very low temperature matrices, typically solidified noble gases or nitrogen at temperatures of 10-20 K. Under the conditions of such
matrix isolation
, reactive species are stabilized because they are prevented from diffusing and therefore from undergoing bimolecular reactions. Matrix-isolated species can be characterized by a variety of normal spectroscopic methods; IR spectroscopy usually provides the greatest amount of structural information. In the study of small ring compounds, the matrix-isolation technique has allowed the characterization and identification of previously elusive compounds such as thiirenes and highly reactive small ring species such as cyclopropenylidenes.
