Irradiation of the N−D stretching band in crystalline deuterium-doped ammonium copper Tutton salt rotates the ammonium ion and changes the conformation of molecules about the copper. The crystal salt exists in at least two different crystal forms, each form containing a particular Jahn−Teller distorted copper conformation. We consider only the “A” form crystal. In this crystal, the minority conformation (B) appears with the majority conformation (A) as the temperature is raised. The spectral holes and antiholes produced by the changes in conformation occur in patterns that depend on the exact frequency of irradiation. Each pattern appears and eventually decays with different kinetics over a range of times. The variation of the hole widths, measured at different temperatures, reveals the presence of various conformations in the crystal lattice. This inhomogeneity is related to the statistical distribution of conformations A and B weighted by their thermal populations. The kinetics of the decay of the holes yields the rate constants of transformation from one conformation to the other. The numerical values and the kinetic model agree well with the experimental data.

The title compound doped with a small amount of deuterium shows infrared bands due to the N-D and O-D stretching vibrations. When one of the N-D bands is irradiated with an infrared laser, holes and antiholes are produced. The pattern of these holes/anti-holes depends on the irradiation time. A ten-minute irradiation produces holes/anti-holes in the N-D bands only. A ten-second irradiation produces holes/antiholes in the O-D bands as well. The features produced by the ten-second irradiation decay during the longer irradiation. Thus, the burning and decay kinetics of the Tutton salts involve processes that occur on at least two time scales.The ammonium Tutton salts, (NH 4 ) 2 X(H 2 O) 6 (SO 4 ) 2 , with X a divalent transition metal ion, form a series of well-known isomorphous crystals. 1 Introducing a small amount of deuterium produces crystals containing some NH 3 D + ions and some HOD molecules. The Tutton salts all crystallize in the monoclinic space group P2 1 /a(#14) with the transition metal ion at a center of inversion. This ion is surrounded by the six water molecules in a distorted octahedron. The hydrogen atoms are equivalent in pairs: thus there are six distinct sets of H-atom sites. The water molecules are hydrogen bonded to the sulfate ions and these, in turn, to the ammonium ions. The ammonium ions sit in general sites, and so there are 4 distinct H positions for the ammonium hydrogen atoms.The deuterium-doped crystals show a series of 10 distinct O-D and N-D bands, one for each distinct H (D) site. The different orientations of the HOD and NH 3 D + molecules have slightly different energies since they put the D-atom in different inequivalent sites. The small energy differences determine the equilibrium distribution of the orientations at a given temperature. 2, 3 We disturb the orientational distribution by irradiating the band corresponding to a given N-D band and then watch the relaxation back to equilibrium in the dark. We have previously reported on the effect of using a hole-burning laser for a period of about 30 min on a variety of ammonium Tutton saltsscobalt, 2 nickel, and their mixed crystals, 4,5 and copper. 6 For the copper salt, we noticed that the relaxation depended strongly on the timesthat is, the relaxation was not a merely monotonic decay, but instead a result of a number of conformational processes occurring on different time scales.Consequently, we developed an irradiation-spectrometer system to examine the kinetics on the order of seconds as well as over longer intervals. In this paper, we briefly explain the new apparatus and then consider the results of irradiating the ammonium nickel Tutton salt for two different periods, 10 s and 10 min. To compare results on such different time scales using a fixed power laser it is necessary to repeat the short irradiation process and its decay many times and co-add the results, and we do just that.For the Cu salt and, to a lesser extent the Co salt, the JahnTeller effect produces a distorted octahedron of water molecules, and this distor...

The title compound, crystallized with a few percent of deuterium, contains some NH(3)D(+) and HOD. At low temperatures, five N-D stretch bands are observed. These belong to two ammonium sites with apparent C(s) symmetry in the low-temperature phase. The N-D bands can be hole-burned with an infrared laser. Burning bands belonging to the A-sites transforms some of them to the higher-energy B-sites. The A- and B-sites probably differ from each other by the arrangement of water and sulfate about the ammonium.

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We have studied the infrared spectra of the OH(D) hydrogen bonds from the water and NH(D) bonds from the NH2 group in the title compound as functions of deuterium concentration and temperature. Some of the vibrational stretching bands are re-assigned. The crystal contains two distinct water molecules. The two OD bands from one HOD molecule merge together as the temperature is raised, suggesting homogenization of the environments of two OD's due to increasing librational motion. The two OD bands from the other HOD molecule behave as expected and do not merge over the temperature range. The two ND bands of the HND group show the overlap or resonances between the ND bands and combination bands. The shifts with temperature of the various stretching bands of the hydrogen-bonded atoms are in agreement with the changes expected from the changes in structure determined by previous X-ray analyses.