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

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 similar to 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 similar to 1.6 x 10(8) spins/root Hz or similar to 2.7 x 10(6) 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 similar to 440 nm for a high spin concentration solid sample (similar to 10(8) spins/mu m(3)) and similar to 6.7 mu m for a low spin concentration liquid sample (similar to 6 x 10(5) spins/mu m(3)). Potential applications of this system range from the imaging of point defects in crystals and semiconductors to measurements of oxygen concentration in biological samples. (C) 2011 American Institute of Physics. [doi:10.1063/1.3581226]