Linked Life Data

19514032

Source:http://linkedlifedata.com/resource/pubmed/id/19514032

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2009-8-24
pubmed:abstractText
The molecular orientation of adsorbed molecules forming self-assembled monolayers can be determined by combining vibrational sum-frequency generation (SFG) measurements with quantum chemical calculations. Herein, we present a theoretical methodology used to simulate the SFG spectra for different combinations of polarizations. These simulations are based on calculations of the IR vectors and Raman tensors, which are obtained from density functional theory computations. The dependency of the SFG vibrational signature with respect to the molecular orientation is presented for the molecules p-nitrothiophenol and 2,4-dinitroaniline. It is found that a suitable choice of basis set as well as of exchange-correlation (XC) functional is mandatory to correctly simulate the SFG intensities and consequently provide an accurate estimation of the adsorbed molecule orientation. Comparison with experimental data shows that calculations performed at the B3LYP/6-311++G(d,p) level of approximation provide good agreement with experimental frequencies, and with IR and Raman intensities. In particular, it is demonstrated that polarization and diffuse functions are compulsory for reproducing the IR and Raman spectra, and consequently vibrational SFG spectra, of systems such as p-nitrothiophenol. Moreover, the investigated XC functionals reveal their influence on the relative intensities, which show rather systematic variations with the amount of Hartree-Fock exchange. Finally, further aspects of the modeling are revealed by considering the frequency dependence of the Raman tensors.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Aug
pubmed:issn
1439-7641
pubmed:author
pubmed:issnType
Electronic
pubmed:day
24
pubmed:volume
10
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2132-42
pubmed:year
2009
pubmed:articleTitle
Theoretical simulation of vibrational sum-frequency generation spectra from density functional theory: application to p-nitrothiophenol and 2,4-dinitroaniline.
pubmed:affiliation
Laboratory of Applied Theoretical Chemistry, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium. julien.guthmuller@fundp.ac.be
pubmed:publicationType
Journal Article