Cryogenic electron spin resonance microimaging probe.

A new probe for acquiring ESR images with microscopic resolution and high spin sensitivity, at a temperature range of ~4.2-300 K, is presented. Details of the probe design, as well as its principle of operation, are provided. The probe incorporates a unique surface loop-gap microresonator. Experimental results demonstrate the system's capability to acquire two - as well as three-dimensional images with a flat test sample of phosphorus-doped silicon. The imaging results also allow verifying the resonator's resonance mode - they show its B(1) distribution, which also makes it possible to estimate the number of spins measured in the sample.

Note: High sensitivity pulsed electron spin resonance spectroscopy with induction detection.

Commercial electron spin resonance spectroscopy and imaging systems make use of the so-called "induction" or "Faraday" detection, which is based on a radio frequency coil or a microwave resonator. The sensitivity of induction detection does not exceed ~3 × 10(8) spins/√Hz. Here we show that through the use of a new type of surface loop-gap microresonators (inner size of 20 µm), operating at cryogenic temperatures at a field of 0.5 T, one can improve upon this sensitivity barrier by more than 2 orders of magnitude and reach spin sensitivities of ~1.5 × 10(6) spins/√Hz or ~2.5 × 10(4) spins for 1 h.

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 ∼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 × 10(8) spins∕√Hz or ∼2.7 × 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 ∼440 nm for a high spin concentration solid sample (∼10(8) spins∕µm(3)) and ∼6.7 µm for a low spin concentration liquid sample (∼6 × 10(5) spins/µm(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.