The first observation of CIDEP generated through the interaction between an excited singlet oxygen molecule and a free radical

Chemically induced dynamic electron polarization (CIDEP) generated through the interaction between the lowest excited singlet oxygen molecule and 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO) radical was observed by the time-resolved ESR technique. Excited singlet oxygen molecules were produced by the triplet sensitizer through energy transfer. Absorptive electron spin polarization was generated on the free radical in the excited singlet oxygen molecule — free radical system, in which the CIDEP generation was interpreted by the radical-triplet pair mechanism with doublet precursor (DP-RTPM). The CIDEP time profile was successfully analyzed by using the Bloch equations. Quenching of 1O2 by β-carotene provides further evidence for DP-RTPM in the 1O2-TEMPO system.