Figure 1. Absorption spectrum (methylcyclohexane) and phosphorescence spectrum (EPA) of 2-phenyl-1-indanone (I). trans+ cis isomerization of stilbene (using 3660 A light and 0.01 M stilbene) showed that intersystem crossing in this ketone occurs with unit efficiency. Irradiation of a 0.014 M benzene solution of IV through a uranium-glass filter for 9 hr resulted in formation of only trace amounts (< 5x) of aldehydic material as shown by nmr analysis. ...