Detection of multiple trap sites in α-deuterated 2-indanone using optically detected magnetic resonance

2-indanone was deuterated by refluxing with D2O and by acid catalyzed enolization, yielding seven distinct molecular species. Samples containing differing total percent deuteration, as determined from mass spectral data, were extracted during the reaction. Using a simulation program, the hydrogen-deuterium exchange was deemed to be a statistically random process. The optically detected magnetic resonance spectrum showed multiple traps in these partially deuterated samples. Seven well-resolved peaks were observed in one of the transitions, while in the other, deconvolution of the spectra assuming Gaussian line shapes yielded all seven lines. In 2-indanone, the third transition is not observed. Correlations were made between the seven peaks in the two transitions by electron-electron spin double resonance, and the zero-field splittings of each of the multiple traps were determined. The seven molecular species generated in the deuteration were correlated to specific zero-field transitions by analyzing the ODMR of samples which had a higher concentration of specific partially deuterated molecules. An analysis of these energies indicated that the shift was the result of a change in the D value which was about 8.1 MHz per additional deuterium. The E value changed little, -2.6 MHz per added deuterium. In addition, the analysis of the integrated intensities indicated that one of the two out-of-plane geometries of the carbonyl group in 2-indanone was favored over the other. Difference in the zero-point energies of the double minimum potential surface was postulated to be the cause. (C) 1998 Elsevier Science B.V. All rights reserved.