Anomalies in the high resolution E.P.R. spectrum of methylene violet

Abstract

The high resolution spectrum of methylene violet in alkaline ethanol has been studied. The spectrum obtained using an X-band spectrometer appears to be anomalous in that one group of lines is unexpectedly broad, of low amplitude and has a temperature-dependent width which is completely different from that of all of the other lines in the spectrum. By combining the X-band results with those obtained from the same radical at the Q-band some of these apparent anomalies can be given a qualitative explanation. One anomaly remains unexplained; namely that the broad lines in the X-band spectrum also appear to have less area under their absorption curve than is to be expected on a statistical basis. (The Q-band spectrum seems to support this contention, but no quantitative information can be derived from it.) The ratio of the area under a broad line to that under an equivalent normal line is determined as a function of temperature. In the temperature range 0 to 85°C this ratio varies between 0·5 and 0·85. Statist...