Sensitivity of optically excited and detected magnetic resonance

Compared to other forms of spectroscopy, the sensitivity of magnetic resonance experiments is relatively low, so that large numbers of spins are necessary for an experiment. This contrasts with related fields, most notably optical spectroscopy, where it has become possible, in recent years, to obtain spectroscopic information from individual atomic and molecular systems. This article investigates possible means for transferring some of this sensitivity advantage to the domain of magnetic resonance and gives numerical estimates of the expected signal-to-noise ratios, as well as experimental examples.