High field EPR

We use high-field EPR at 90, 180 and 270GHz to exploit the extra sensitivity and resolution that it offers when studying a large range of systems. We can study systems with large zero field splittings and resolve features that are not distinct at 10GHz or even 35GHz where most commercial spectrometers operate. The example below shows a 94GHz spectrum of DPPH, a common standard sample, and fluoranthene, an organic conductor which has an extremely narrow line.

dpph2

At 10GHz, these two features would not be separated, so high field EPR allows us to detect a small amount of one material in the presence of another.