EFFICIENCY OF THE PHOTOPROCESSES LEADING TO SINGLET OXYGEN (1-DELTA-G) GENERATION BY ALPHA-TERTHIENYL - OPTICAL-ABSORPTION, OPTOACOUSTIC CALORIMETRY AND INFRARED LUMINESCENCE STUDIES

Abstract— …The triplet energy of α‐terthienyl has been determined by heavy atom‐induced optical absorption; the value of 39.7 ±1.5 kcal/mol is consistent with earlier energy transfer work. Combining this result with calorimetric data from optoacoustic calorimetry indicates that intersystem crossing occurs with at least 90% efficiency in polar and non‐polar solvents. The quantum yields for singlet oxygen formation via energy transfer from triplet α‐terthienyl have been obtained from time‐resolved measurements of its IR phosphorescence; these yields are in the 0.6‐0.8 range in non‐polar and polar (hydroxylic and non‐hydroxylic) solvents. Copyright © 1990, Wiley Blackwell. All rights reserved