Cryogenic sample eject system for electron paramagnetic resonance spectrometers.

We present a fully automated cryogenic sample insertion and ejection system for use with low-temperature EPR probes. We show how the system can be implemented on a conventional EPR spectrometer and that ejection and insertion is reliably possible at temperatures down to 10 K. Furthermore, we investigate the glass properties of a 0.1 mM sample of TEMPO in d-glycerol/DO (25/75, v/v) by measuring the electron phase memory time T in addition to determining the effective spin concentration from a PELDOR/DEER background trace. These experiments were done either using the sample eject system or samples that were manually flash frozen. We show that using the ejection system we can consistently obtain a better glass matrix as indicated by the longer T times and the lower effective concentrations.