Time-domain chirp electron nuclear double resonance spectroscopy in one and two dimensions

Abstract

It is demonstrated by theory and experiment that time-domain broadband electron nuclear double resonance (ENDOR) spectroscopy can be performed by using radio frequency chirp pulses. The chirp ENDOR experiment is shown to have a sensitivity comparable to that of established pulsed ENDOR experiments while featuring at the same time a higher resolution. Two pulsed schemes are proposed for chirp ENDOR that are related to the Davies- and Mims-ENDOR experiments. A simple two-step phase cycle can remove the contributions from unwanted coherence transfer pathways and, unlike in time-domain ENDOR with pulses of fixed radio frequency, no quadrature readout is needed. The basic chirp ENDOR experiment can easily be extended by applying concepts from electron spin echo envelope modulation and nuclear magnetic resonance spectroscopy. A novel hyperfine sublevel correlation (HYSCORE) experiment based on chirp ENDOR is proposed.