Vibrational Frequencies of the Isotopic Water Molecules; Equilibria with the Isotopic Hydrogens

1943 ◽  
Vol 11 (3) ◽  
pp. 101-109 ◽  
Author(s):  
W. F. Libby
Keyword(s):  
Vibrational Frequencies ◽  
Water Molecules ◽  
Isotopic Water

Note: Crystal Structure, Vibrational Spectrum and Thermal Behavior of the Ammonium Hexathiohypodiphosphate Dihydrate, (NH4)4P2S6 · 2H2O

2007 ◽  
Vol 62 (8) ◽  
pp. 1102-1106 ◽  
Author(s):  
Mimoza Gjikaj ◽  
Wolfgang Brockner
Keyword(s):  
Crystal Structure ◽  
Thermogravimetric Analysis ◽  
Vibrational Spectrum ◽  
Ir Spectra ◽  
Thermal Behavior ◽  
Single Crystals ◽  
Vibrational Frequencies ◽  
Water Molecules ◽  
Ft Ir ◽  
Ft Raman

Single crystals of (NH4)4P2S6 ・ 2H2O could be obtained and the crystal structure determined (monoclinic, P21/c with a = 6.931(1), b = 12.730(2), c = 17.446(2) Å , β = 96.87(1)°, V = 1528.2(4) Å3, Z = 4). The NH4 +, and [P2S6]4− ions and the water molecules are involved in an extended hydrogenbonding network. The FT-Raman and FT-IR spectra have been recorded and the observed vibrational frequencies assigned to tetrahedral NH4 + and [P2S6]4− (D3d) ions as well as to H2O molecules. The thermogravimetric analysis has shown that (NH4)4P2S6 · 2H2O starts to decompose at around 60 °C (up to 170 °C), but no distinct intermediates could be observed.

scholarly journals Theory of isotope fractionation on facetted ice crystals

2011 ◽  
Vol 11 (6) ◽  
pp. 17423-17445
Author(s):  
J. Nelson
Keyword(s):  
Isotope Fractionation ◽  
Surface Processes ◽  
Water Isotopes ◽  
Water Molecules ◽  
Temperature Changes ◽  
Temperature Reconstructions ◽  
Fractionation Model ◽  
Kinetic Fractionation ◽  
Isotopic Water ◽  
Fractionation Coefficient

Abstract. Present models of the differential incorporation of isotopic water molecules into vapor-grown ice omit surface processes that may be important in temperature reconstructions. This article introduces a model that includes such surface processes and shows that differences in deposition coefficients for water isotopes can produce isotope fractionation coefficients that significantly differ from those of existing theory. For example, if the deposition coefficient of H218O differs by just 5 % from that of ordinary water (H216O), the resulting fractionation coefficient at 20 % supersaturation may deviate from the kinetic fractionation (KF) prediction by up to about ±17 ‰. Like the KF model, this "surface-kinetic" fractionation model generally predicts greater deviation from the equilibrium prediction at higher supersaturations; indeed, the sensitivity to supersaturation far exceeds that to temperature. Moreover, the model introduces possible new temperature dependencies from the deposition coefficients. These parameters need to be constrained by new laboratory measurements; nevertheless, the theory suggests that observed δ18O changes in ice samples are unlikely to be due solely to temperature changes.

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