This disclosure provides systems, methods, and apparatus related to depth well logging. In one aspect, an apparatus includes a radio frequency (RF) coil and a magnetic field sensing device. The apparatus is configured to be positioned in a first magnetic field. The first magnetic field polarizes nuclear spins of species in a detection region proximate the apparatus. The apparatus generates a second magnetic field for a time period with the RF coil to excite the nuclear spins of the species in the detection region. Then, the apparatus measures electromagnetic radiation, using the magnetic field sensing device, generated by the species as a result of the excitation of the nuclear spins.
STATEMENT OF GOVERNMENT SUPPORT
 This invention was made with government support under Contract No. DE-AC02-05CH11231 awarded by the U.S. Department of Energy. The government has certain rights in this invention.