INTRAMOLECULAR THERMAL MOTIONS IN LIQUID N-PROPANOL (PLUS GLYCEROL), A PROTON MAGNETIC-RELAXATION STUDY .2.

The proton magnetic relaxation times T-1 and T-2 of the four n-propano l species HOC3D7, DOCH2CD2CD3, DOCD2CH2CD3, and DOCD2CD2CH3 have been measured at the resonance frequency v = 12 MHz as a function of the te mperature in the range 80 < T/K < 330. T-1 measurements were performed at a second frequency, v = 48 MHz, as well. Further measurements of t he same general kind were done on the mixtures n-propanol + 50 mol % g lycerol (glycerol-d(5) and -d(8)) and n-propanol + 70 mol % glycerol ( glycerol-d(5) and -d(8)). Isotopic dilution measurements with constant content of propanol and varying degree of deuteration were made to ob tain the intramolecular relaxation rates. The proton NMR spectra of th e four propanol species were recorded at T = 130 K. From all these dat a correlation times for the various proton-proton vectors were derived . It turned out that to each motion a slow and a fast mode contributio n exists; however, the results are not compatible with the model of a molecule as a system of rigid bodies connected by axes about which rot ation occurs. A formal description and interpretation is given involvi ng the molecule concept without the presupposition of a microscopic ri gid body.