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Proton dynamics in ice VII at high pressures
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10.1063/1.4816630
/content/aip/journal/jcp/139/4/10.1063/1.4816630
http://aip.metastore.ingenta.com/content/aip/journal/jcp/139/4/10.1063/1.4816630

Figures

Image of FIG. 1.
FIG. 1.

Internal frequencies of HO ice-VII versus pressure at 295 K showing the measured Raman OH symmetric (open triangles and circles) and asymmetric (solid triangles and circles) stretch frequencies ν and ν up to 27 GPa. Lower inset: Weighted average measured IR stretch frequency ν, between 31 and 55 GPa (crosses, asterisks ). Upper inset: measured IR bending frequencies. Solid and dashed lines are best fits to the data. The frequencies for calculating Ke(H) between 5 and 55 GPa were taken from the fitted lines.

Image of FIG. 2.
FIG. 2.

Measured IR frequencies of translation T (open squares ) and libration L (open circles ). Solid lines T and L are best fit to the data. The frequencies for calculating Ke(H) between 5 and 64 GPa were taken from the fitted lines. Solid circle: weighted average frequency of ice Ih at 15 K measured using INS. Solid square: average over measured INS frequencies of 20 K ice and 253 K super cooled water. Note the smooth lines joining the ambient and high pressure data of different phases of HO.

Image of FIG. 3.
FIG. 3.

Calculated mean kinetic energies Ke(H) (circles) and Ke(O) (squares) vs pressure in HO ice VII at 298 K. Solid lines are best fits to the data points. Ambient pressure data points: (i) diamond – an average over revised calculated and experimental values of ice Ih and bulk water listed in Table I and (ii) open square – calculated by Eq. (3) utilizing INS measured VDOS spectra of ice Ih. Error bars at 35 GPa represent the typical uncertainty in the calculated values between 5 and 55 GPa. The error bars at 61.5 GPa are considerably larger due to uncertainties in the optically measured frequencies. Note the smooth line joining the ambient and high pressure data of different phases of water and ice.

Image of FIG. 4.
FIG. 4.

Relative contributions of lattice external and internal modes to the mean kinetic energies of the proton (solid symbols) and of the oxygen atom (open symbols) in HO ice VII at 298 K versus pressure. Squares: translation; circles: librations; triangles: cumulative internal modes. Solid and dashed lines are best fits to the data.

Image of FIG. 5.
FIG. 5.

Calculated mean kinetic energies Ke(D) (solid circles) and Ke(O) (solid squares) vs pressure in DO ice VII at 298 K. Solid lines are best fits to the data points. The ambient pressure data points (open circle and square) were calculated using Eq. (3) and utilizing the measured INS VDOS spectra of 15 K deuterated ice Ih. Note the smooth line joining the ambient and high pressure data of different phases of DO.

Tables

Generic image for table
Table I.

Comparison of previously calculated Ke(H) values (in meV units) and the new ones in water obtained by including the measured libration spectra. The results of previous and new analysis of the DINS experimental HO data are also presented.

Generic image for table
Table II.

List of the geometrical parameters versus pressure of HO ice VII at room temperature, used for calculating the kinetic energies of the H- and O-atoms, Ke(H) and Ke(O) (in meV units) shown in bold face in the two bottom lines bellow. The force constants (in 10dyn/cm units) are those found to best reproduce the listed literature frequencies. S(H) and S(O) are the deduced shares of the proton and of the oxygen, respectively, in the kth mode of motion: k = T-translation, L-libration, 1-symmetric stretch (ss), 2-bending (b), 3-asymmetric stretch (ass). Literature frequencies and S values were used as input data in Eq. (3) .

Generic image for table
Table III.

List of the geometrical parameters versus pressure of DO ice VII at room temperature, used for calculating the kinetic energies of the D- and O-atoms, Ke(D) and Ke(O) (in meV units) shown in bold face in the two bottom lines below. The force constants are those found to best reproduce the listed literature frequencies. S(D) and S(O) are the deduced shares of the proton and of the oxygen, respectively, in the kth mode of motion: k = T-translation, L-libration, 1-symmetric stretch (ss), 2-bending (b), 3-asymmetric stretch (ass). Literature frequencies and S values were used as input data in Eq. (3) from which Ke(D) and Ke(O) (in meV units) were calculated versus pressure.

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/content/aip/journal/jcp/139/4/10.1063/1.4816630
2013-07-31
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Proton dynamics in ice VII at high pressures
http://aip.metastore.ingenta.com/content/aip/journal/jcp/139/4/10.1063/1.4816630
10.1063/1.4816630
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