Chapter Three - Optical Atomic Magnetometry for Ultra-Low-Field NMR Detection

Abstract

Abstract This chapter deals with detection of nuclear magnetic resonance (NMR) signals in the ultra-low-field (ULF) regime, by means of optical atomic magnetometers (OAMs). A general introduction is provided about specific NMR features occurring when nuclei precess in microtesla fields, or weaker. The advantages of detecting the NMR signal by means of an OAM are here preliminarily discussed. A further general introduction is provided about basic ideas and recent progresses in optical atomic magnetometry. A section is devoted to the detailed presentation of an example of dual-channel atomic magnetometer which was used to detect the signal produced by protons of a remotely polarized water sample in an unshielded environment, taking advantage of its differential nature. Results reported in a wide set of similar experiments are then discussed in a general synthesis of the interdisciplinary activity performed on the main subject of this work. We report on progresses made in the ULF-NMR applications in imaging, microfluidic, zero- and near-zero field spectroscopy. The non-conventional NMR detection schemes discussed in this chapter are in some cases profitably coupled with non-conventional methods for sample polarization. Some experiments devoted to non-conventional preparation of the nuclear spin state are considered and briefly discussed, as well.