The Observation and Dynamics of 1H NMR Spin Noise in Methanol

The observation of 1H spin noise in relation to prior established magnetization and radiation damping has revealed a correlated dynamics. The spin noise of methyl satellites in 13C-enriched methanol was observed in the presence of an antiphase magnetization, created by the combination of 1H–13C J coupling evolution and radiofrequency (RF) pulses. A gradient pulse was applied to remove residue spin coherence coming from the RF pulses, and as a result spin noise phenomena were uncovered. While magnetization was in an inverted metastable state, the spin–spin relaxation time was shortened to prevent a super radiation burst. The relation between magnetization, radiation damping, and absorption or emission of the spin noise of methyl satellites has been studied. In relation to magnetization and radiation damping, spin noise bump and dip have been observed simultaneously in the same molecule. Both can be created through a proper inversion of magnetization. The revealed spin noise dynamics of spin system coupling to the probe circuit via radiation damping allows performance of a transformation from dip into bump by proper application of pulses combined with 1H–13C J coupling evolution.