Frequency-Domain Analysis of Spin Motion Using Modulated-Gradient NMR

In pulsed-gradient spin-echo NMR, one measures the disof rotational dipolar auto-correlation spectral density via the ‘‘probe’’ of the spin relaxation times, where T1 samples at placement of nuclear spins over the time interval, D, between two gradient pulses, of duration d and amplitude g , positions v0 and 2v0 , while T1r samples at v1 and 2v1 . The purpose of the present Communication is to demonplaced in the dephasing and rephasing evolution periods of a spin-echo RF pulse sequence. For sufficiently narrow grastrate an implementation of the frequency-domain analysis using two different modulation waveforms for the effective dient pulses, the experiment is nicely described in terms of a scattering wave-vector formalism so that the echo ampligradient. We term this method frequency-domain analysis of spin motion using modulated-gradient NMR (FD-MGtude is inherently acquired in a time–wave-vector domain as NMR). We note that the use of oscillating gradients to probe molecular motion has been recently reported by Wang et al. (4) . That approach, originally suggested in Refs. (1–3) , E(q , D) Å * `