CH-Stretching Vibrational Trends in Natural Gas Hydrates Studied by Quantum-Chemical Computations
2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 30, 17084-17091 p.Article in journal (Refereed) Published
Vibrational Raman spectrosopy of hydrocarbon CH-stretching vibrations is often-used to study natural gas, hydrates., In this work, CH-stretching vibrational, Raman spectra of hydrocarbon molectles (CH4, C2H6, C(3)H6, C3H8, C4H8, i-C4H10, and n-C4H10) encapsulated in the water cages (D, ID, T, P, H, and I) of the SI, sII, sH, and sK crystal phases. are derived from quantum-chemical computations at the omega B97X-D/6-311++G(24,2p) level of theory. The trends of CH-stretching vibrational frequencies Of hydrocarbon Molecules in natural gas hydrates are found to follow the prediction by the loose cage tight cage model: as the size of Water cavity increases, the CH frequencies will first decrease and: then increase until equal to-that in the gas phase. In the "tight cage" situation, the frequency will be greater than in the gas phase; in the "loose cage" situation, the frequency will be smaller or asymptotic to that in the gas phase. Furthermore, the OH-stretching frequencies are sensitive to the H-bond configuration, and the varying strengths of H-bonds for different configurations are reflected by,the frequency distribution in the corresponding subspectra.
Place, publisher, year, edition, pages
American Chemical Society , 2015. Vol. 119, no 30, 17084-17091 p.
IdentifiersURN: urn:nbn:se:liu:diva-120872DOI: 10.1021/acs.jpcc.5b01903ISI: 000359031900007OAI: oai:DiVA.org:liu-120872DiVA: diva2:849404
Funding Agencies|Swedish Research Council (VR); Swedish Supercomputer Center (SNIC/NSC); China Scholarship Council 2015-08-282015-08-282015-09-17