Quantum dynamics of adsorbed normal- and para-H2, HD, and D2 in the microporous framework MOF-74 analyzed using infrared spectroscopy

Title:
Quantum dynamics of adsorbed normal- and para-H2, HD, and D2 in the microporous framework MOF-74 analyzed using infrared spectroscopy
Authors:
FitzGerald, Stephen; Hopkins, Jesse B.; Burkholder, B.; Friedman, Michael; Rowsell, Jesse L. C.
Abstract:
Low-temperature diffuse reflectance infrared spectroscopy is used to measure the quantum dynamics of molecular hydrogen and its isotopologues adsorbed in the microporous material MOF-74. At least two distinct adsorption sites are revealed by increasing the concentration of H2 within the material and monitoring the successive appearance of absorption bands with decreasing bathochromic shifts (or "redshifts") from the unperturbed (gas-phase) vibrational frequencies. Under conditions wherein both the primary and neighboring secondary sites are occupied, additional frequency shifts are observed that confirm the interactions among the adsorbed molecules are non-negligible. Ortho to para conversion of the adsorbed normal-H2 is observed to occur within minutes and this process is accelerated when both primary and secondary sites are occupied. Translational sidebands are also observed, providing an estimation of 124 cm-1 for the frequency of the center-of-mass motion of H2 at the primary adsorption site. The frequency shifts of the absorption bands of HD and D2 diverge from the predictions of a simple isotope effect, emphasizing the importance of the zero-point energy contribution.
Citation:
FitzGerald, S.A., J. Hopkins, B. Burkholder, M. Friedman, and J.L.C. Rowsell. 2010. "Quantum dynamics of adsorbed normal- and para-H2, HD, and D2 in the microporous framework MOF-74 analyzed using infrared spectroscopy." Physical Review B 81(10): 104305.
Publisher:
American Physical Society
DATE ISSUED:
2010-03-01
Department:
Physics and Astronomy
Type:
article
PUBLISHED VERSION:
10.1103/PhysRevB.81.104305
PERMANENT LINK:
http://hdl.handle.net/11282/310151

Full metadata record

DC FieldValue Language
dc.contributor.authorFitzGerald, Stephenen_US
dc.contributor.authorHopkins, Jesse B.en_US
dc.contributor.authorBurkholder, B.en_US
dc.contributor.authorFriedman, Michaelen_US
dc.contributor.authorRowsell, Jesse L. C.en_US
dc.date.accessioned2013-12-23T16:26:51Zen
dc.date.available2013-12-23T16:26:51Zen
dc.date.issued2010-03-01en
dc.identifier.citationFitzGerald, S.A., J. Hopkins, B. Burkholder, M. Friedman, and J.L.C. Rowsell. 2010. "Quantum dynamics of adsorbed normal- and para-H2, HD, and D2 in the microporous framework MOF-74 analyzed using infrared spectroscopy." Physical Review B 81(10): 104305.en_US
dc.identifier.issn1098-0121en_US
dc.identifier.urihttp://hdl.handle.net/11282/310151en
dc.description.abstractLow-temperature diffuse reflectance infrared spectroscopy is used to measure the quantum dynamics of molecular hydrogen and its isotopologues adsorbed in the microporous material MOF-74. At least two distinct adsorption sites are revealed by increasing the concentration of H2 within the material and monitoring the successive appearance of absorption bands with decreasing bathochromic shifts (or "redshifts") from the unperturbed (gas-phase) vibrational frequencies. Under conditions wherein both the primary and neighboring secondary sites are occupied, additional frequency shifts are observed that confirm the interactions among the adsorbed molecules are non-negligible. Ortho to para conversion of the adsorbed normal-H2 is observed to occur within minutes and this process is accelerated when both primary and secondary sites are occupied. Translational sidebands are also observed, providing an estimation of 124 cm-1 for the frequency of the center-of-mass motion of H2 at the primary adsorption site. The frequency shifts of the absorption bands of HD and D2 diverge from the predictions of a simple isotope effect, emphasizing the importance of the zero-point energy contribution.en_US
dc.language.isoen_USen_US
dc.publisherAmerican Physical Societyen_US
dc.identifier.doi10.1103/PhysRevB.81.104305en
dc.subject.departmentPhysics and Astronomyen_US
dc.titleQuantum dynamics of adsorbed normal- and para-H2, HD, and D2 in the microporous framework MOF-74 analyzed using infrared spectroscopyen_US
dc.typearticleen_US
dc.identifier.journalPhysical Review Ben_US
dc.identifier.volume81en_US
dc.identifier.issue10en_US
dc.identifier.startpage104305en_US
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