Patent ID: 7586305

Claim:
A method for determination of the absolute number of electron spins in an extended sample with the assistance of an apparatus for measuring magnetic resonance, the extended sample being disposed within a measurement volume of a radio frequency (RF) resonator of the apparatus during an electron spin resonance measurement, the method comprising the steps of: a) determining a spatial sensitivity profile of the RF resonator over the measurement volume; b) determining, at a defined position within the measurement volume, a resonator sensitivity constant using a calibration sample which is small compared to the measurement volume, the calibration sample having a known number of electron spins; c) measuring a magnetic resonance signal of the extended sample in the apparatus, wherein the extended sample has a known spatial distribution in the measurement volume; d) weighting the magnetic resonance signal with an integral of the spatial sensitivity profile of the RF resonator over a partial volume of the measurement volume occupied by the extended sample; and e) determining a number of electron spins in the extended sample as a quotient between a weighted resonance signal of step d) and the resonator sensitivity constant of step b).