Study of molecular dynamics and cross relaxation in tetramethylammonium hexafluorophosphate (CH3)4NPF6 by 1H and 19F NMR

(CH3)4NPF6 is studied by NMR measurements to understand the internal motions and cross relaxation mechanism between the heterogeneous nuclei. The spin lattice relaxation times (T1) are measured for 1H and 19F nuclei, at three (11.4, 16.1 and 21.34 MHz) Larmor frequencies in the temperature range 350-50 K and 1H NMR second moment measurements at 7 MHz in the temperature range 300-100 K employing home made pulsed and wide-line NMR spectrometers. 1H NMR results are attributed to the simultaneous reorientations of both methyl and tetramethylammonium groups and motional parameters are evaluated. 19F NMR results are attributed to cross relaxation between proton and fluorine and motional parameters for the PF6 group reorientation are evaluated.