High-sensitivity Q-band electron spin resonance imaging system with submicron resolution

Abstract

A pulsed electron spin resonance (ESR) microimaging system operating at the Q-band frequency range is presented. The system includes a pulsed ESR spectrometer, gradient drivers, and a unique high-sensitivity imaging probe. The pulsed gradient drivers are capable of producing peak currents ranging from ∼9 A for short 150 ns pulses up to more than 94 A for long 1400 ns gradient pulses. Under optimal conditions, the imaging probe provides spin sensitivity of ∼1.6 108 spinsHz or ∼2.7 106 spins for 1 h of acquisition. This combination of high gradients and high spin sensitivity enables the acquisition of ESR images with a resolution down to ∼440 nm for a high spin concentration solid sample (∼108 spinsm3) and ∼6.7 m for a low spin concentration liquid sample (∼6 105 spinsm3). Potential applications of this system range from the imaging of point defects in crystals and semiconductors to measurements of oxygen concentration in biological samples. © 2011 American Institute of Physics.