Spin-echo in the phosphorescent triplet state of crystalline 2-indanone

Abstract

The relative ordering of the three sublevels of the phosphorescent triplet state of 2-indanone was determined by correlating optically detected magnetic resonance (ODMR) spectra taken with the sample in a Zeeman field with calculated spectra. Spin coherence was observed in the phosphorescent triplet state of 2-indanone in neat and doped single crystals by conventional and real time detection. The Hahn electron spin-echo signal was observed in real time by a pulse sequence which terminates with a continuous-wave low power field (LPF). The Fourier transform of the echo decay as a function of τ yielded a peak at 9.0 MHz which was attributed by isotopic substitution studies to nuclear coupling of the triplet electrons via the α-protons in the molecule. Dephasing of the Hahn and stimulated spin echo in 2-indanone due to energy trapping was measured with chemically mixed crystals of 2-indanone prepared with varying concentrations of quinoxaline. Energy transfer to quinoxaline which served as a deep trap contributed to the dephasing of the echo.