The Magnetic Moments of the Proton and the Deuteron. The Radiofrequency Spectrum ofH2in Various Magnetic Fields

Nuclear spin isomers of guest molecules in H 2 @C 60 , H 2 O@C 60 and other endofullerenes

“…Based on a variety of spectroscopic studies, the emerging answer is a qualified 'yes' [14,[32][33][34], and references therein] although some coupling of rotational and internal translation modes of the endo H 2 has been predicted theoretically [35] and detected spectroscopically [32]. (It has not, however, been possible to resolve by NMR the spin-rotation fine structure in H 2 @C 60 that is resolved in gas phase molecular beam measurements [36].) Similarly, the low-temperature FIR spectrum of H 2 O@C 60 resembles that of water in the gas phase [14].…”

Spectroscopy of light-molecule endofullerenes

“…A similar spectrum is obtained at the molecular resonance frequency, in this case because the two single-quantum transitions of the J = 1 'molecular spin' are split into three components by coupling to the I = 1 nuclear angular momentum [78,79]. These phenomena were observed and described with great detail and clarity by Ramsey and co-workers [78,80,81] well before the bulk NMR experiments of Purcell, Pound and Bloch.…”

“…Phenomena such as precession and nutation in a magnetic field, which are central topics in NMR [76,77], are also observed for the rotational angular momenta of molecules. For example, the molecular magnetic resonance of J = 1 ortho-H 2 is observed at approximately one-sixth of the proton Larmor frequency, in the same magnetic field [78,79]. Nuclear spin angular momenta and molecular rotational angular momenta may couple, in much the same way as two nuclear spins in the same molecule.…”

“…Consider, for example, the ortho-H 2 ground state, which has molecular angular momentum J = 1 and nuclear spin angular momentum I = 1. The magnetic resonance spectrum at the proton Larmor frequency displays six peaks, since the two single-quantum transitions of the I = 1 nuclear spin are both split into three components by coupling to the J = 1 molecular angular momentum [78,79]. A similar spectrum is obtained at the molecular resonance frequency, in this case because the two single-quantum transitions of the J = 1 'molecular spin' are split into three components by coupling to the I = 1 nuclear angular momentum [78,79].…”

“…The magnetic resonance spectrum at the proton Larmor frequency displays six peaks, since the two single-quantum transitions of the I = 1 nuclear spin are both split into three components by coupling to the J = 1 molecular angular momentum [78,79]. A similar spectrum is obtained at the molecular resonance frequency, in this case because the two single-quantum transitions of the J = 1 'molecular spin' are split into three components by coupling to the I = 1 nuclear angular momentum [78,79]. These phenomena were observed and described with great detail and clarity by Ramsey and co-workers [78,80,81] well before the bulk NMR experiments of Purcell, Pound and Bloch.…”