Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 419364
Title Structure Matters: Correlating Temperature Dependent Electrical Transport through Alkyl Monolayers with Vibrational and Photoelectron Spectroscopies
Author(s) Shpaisman, H.; Seitz, H.; Yaffe, O.; Roodenko, K.; Scheres, L.M.W.; Zuilhof, H.; Chabal, Y.J.; Sueyoshi, T.; Kera, S.; Ueno, N.; Vilan, A.; Cahen, D.
Source Chemical Science 3 (2012). - ISSN 2041-6520 - p. 851 - 862.
Department(s) Laboratory for Organic Chemistry
Publication type Refereed Article in a scientific journal
Publication year 2012
Keyword(s) self-assembled monolayers - hydrogen-terminated silicon - h stretching modes - molecular junctions - charge-transport - through-bond - infrared-spectroscopy - electronic transport - organic monolayers - thiol monolayers
Abstract Freezing out of molecular motion and increased molecular tilt enhance the efficiency of electron transport through alkyl chain monolayers that are directly chemically bound to oxide-free Si. As a result, the current across such monolayers increases as the temperature decreases from room temperature to [similar]80 K, i.e., opposite to thermally activated transport such as hopping or semiconductor transport. The 30-fold change for transport through an 18-carbon long alkyl monolayer is several times the resistance change for actual metals over this range. FTIR vibrational spectroscopic measurements indicate that cooling increases the packing density and reduces the motional freedom of the alkyl chains by first stretching the chains and then gradually tilting the adsorbed molecules away from the surface normal. Ultraviolet photoelectron spectroscopy shows drastic sharpening of the valence band structure as the temperature decreases, which we ascribe to decreased electron–phonon coupling. Although conformational changes are typical in soft molecular systems, in molecular electronics they are rarely observed experimentally or considered theoretically. Our findings, though, indicate that the molecular conformational changes are a prominent feature, which imply behavior that differs qualitatively from that described by models of electronic transport through inorganic mesoscopic solids
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