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Vibrational Anharmonicity in the Water-Nitrate Complex, Ice, and Gas Hydrates: Applications to Spectroscopy and Thermal Transport

Kratz, Eric G. (2014) Vibrational Anharmonicity in the Water-Nitrate Complex, Ice, and Gas Hydrates: Applications to Spectroscopy and Thermal Transport. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Vibrational anharmonicity strongly influences the properties of gas-phase complexes and solids. Anharmonicity is responsible for the observation of “forbidden” vibrational transitions, thermal expansion, and phonon-phonon scattering. In the first portion of this dissertation the vibrational spectra of [(NO3-)(H2O)] and its isotopologues are examined through effective Hamiltonian and vibrational configuration interaction calculations employing ab initio force constants. While a harmonic treatment of the [(NO3-)(H2O)] infrared absorption spectrum predicts two OH stretch transitions, four strong
peaks are experimentally observed. Anharmonic vibrational calculations confirm that the “extra” transitions are due to the rocking motion of the water molecule relative to the nitrate ion and a Fermi resonance between the OH stretch and water bend overtone. The second part of the dissertation explores the nature of the vibrational anharmonicity of gas hydrates and ice Ih as well as its effects on the structure and thermal conductivity. The
arrangement of the hydrogen atoms in the solids and the gas-water interactions are found to have a strong influence on some of the properties of the crystals. Coarse-grained simulations and analytic scattering approximations qualitatively reproduce the observed behavior of the thermal conductivity of gas hydrates and ice. In addition, the calculations reveal that guest-host coupling cannot fully explain the differences in the thermal conductivity of gas hydrates and ice.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kratz, Eric G.
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairJordan, Kenneth D.jordan@pitt.eduJORDAN
Committee MemberHutchison, Geoffrey R.geoffh@pitt.eduGEOFFH
Committee MemberWaldeck, David H.dave@pitt.eduDAVE
Committee MemberMcGaughey, Alan J.
Date: 23 September 2014
Date Type: Publication
Defense Date: 14 May 2014
Approval Date: 23 September 2014
Submission Date: 13 August 2014
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 153
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Quasi-harmonic thermal conductivity phonon infrared proton disorder
Date Deposited: 23 Sep 2014 15:02
Last Modified: 15 Nov 2016 14:23


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