Abstract
We have detected and manipulated the naturally occurring statistical polarization in nuclear spin ensembles using magnetic resonance force microscopy. Using protocols previously developed for detecting single electron spins, we have measured signals from ensembles of nuclear spins in a volume of roughly with a sensitivity of roughly 2000 net spins in a averaging window. Three systems have been studied, nuclei in , and nuclei (protons) in both polymethylmethacrylate and collagen, a naturally occurring protein. By detecting the statistical polarization, we not only can work with relatively small ensembles, but we eliminate any need to wait a longitudinal relaxation time to polarize the spins. We have also made use of the fact that the statistical polarization, which can be considered a form of spin noise, has a finite correlation time. A method similar to one previously proposed by Carlson et al. [Bull. Am. Phys. Soc. 44, 541 (1999)] has been used to suppress the effect of the statistical uncertainty and extract meaningful information from time-averaged measurements. By implementing this method, we have successfully made nutation and transverse spin relaxation time measurements in at low temperatures.
1 More- Received 7 January 2005
DOI:https://doi.org/10.1103/PhysRevB.72.024413
©2005 American Physical Society