Nuclear orientation and NMR of oriented nuclei

Recent developments in low-temperature nuclear orientation

“…The improvement of nuclear demagnetisation methods opened the perspective of NO at sub-millikelvin temperatures (Ono et a1 1980). Adiabatic passsage NMR (Barclay et a1 1972) and pulsed NMRON (Wilson and Chaplin 1981) were introduced, and the quadrupole structure in the NMRON of heavy ions in ferromagnetic hosts was resolved (Callaghan et a1 1976a, b, Hagn et a1 1979. Thermal cycling methods were developed to permit accurate dynamic (relaxation time) measurements on NO samples (Klein 1977), and the first NMRON on implanted samples (Fox 1971, see also Stone 1980a, implantation into cold hosts (Herzog et a1 1977, see also Herzog 1985) and NMR on brute force oriented samples (BFNMR; see Brewer 1977a) were demonstrated.…”

“…The possibility of using pulsed RF techniques in NMRON has been thoroughly explored by the Canberra group (see Wilson andChaplin 1981, Chaplin andWilson 1986). Two types of methods have emerged: true pulsed NMR methods, in which short monochromatic RF pulses of high amplitude are applied to turn the nuclear ensemble through a particular angle; and the so called pulsed-FM methods, in which frequency-modulated pulses of intermediate amplitude are applied for longer times.…”

“…The Canberra group have also carried out true pulsed NMRON experiments (see Wilson andChaplin 1981, Chaplin andWilson 1986), in which the pulse amplitudes B, are of order lOOpT or more, and the lengths r of order 10 ps or less. No FM of the pulse carrier frequency is required, since the short pulse length in the time domain ensures a sufficient bandwidth in the frequency domain to affect a considerable fraction of the nuclei in the inhomogeneously broadened resonant region.…”