title: Ammonium ions in alkali metal halide crystals: tunnelling and spin relaxation.
abstract: We have used low energy inelastic neutron scattering spectroscopy to examine the tunnelling spectroscopy of the ammonium ion in the (NH4)0.02Rb(x)K(0.98-x)I system. The concentration of different species were varied as x increased, this was followed systematically and the first consistent assignment scheme for these features is given. Differences were also found for the relaxation rate of the spin temperature inversions that could be generated in these species. At a critical concentration--about x = 0.04 mole fraction--the relaxation rates of the species changed dramatically.
authors.affiliation: The ISIS Facility, The Rutherford Appleton Laboratory, CCLRC, Chilton, UK OX11 0QX. j.tomkinson@rl.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Tomkinson
authors.forename: M T F
authors.initials: MT
authors.lastname: Telling
mesh_terms: D003460:Crystallization; D006219:Halogens / Q000737:chemistry*; D008672:Metals, Alkali / Q000737:chemistry*; D009502:Neutrons; D011789:Quantum Theory; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D006219:Halogens; D008672:Metals, Alkali; D000644:Quaternary Ammonium Compounds