title: Helical versus all-trans conformations of oligo(ethylene glycol)-terminated alkanethiol self-assembled monolayers.
abstract: The complex mixture of conformational states exhibited by oligo(ethylene glycol)-terminated alkanethiols on Ag and Au surfaces is explored by polarization-dependent X-ray absorption spectroscopy. Three self-assembled monolayers (SAMs) with known helical or all-trans conformations are used as references to characterize a SAM with unknown conformations. This case study is used as a prototype for developing a systematic framework to extract the conformations of SAMs from the polarization dependence of several orbitals. In the case at hand, these are associated with the C-H/Rydberg bonds of the alkane, the C-H/Rydberg bonds of ethylene glycol, and the C-C bonds of the backbone. The C-H/Rydberg orbitals of the alkane and ethylene glycol are distinguished via the chemical shift of the corresponding C 1s core levels.
authors.affiliation: Department of Physics, University of Wisconsin-Madison , 1150 University Avenue, Madison, Wisconsin 53706, United States.
authors.forename: Phillip S
authors.initials: PS
authors.lastname: Johnson
authors.forename: Mohit
authors.initials: M
authors.lastname: Goel
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Abbott
authors.forename: F J
authors.initials: FJ
authors.lastname: Himpsel
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D019855:Ethylene Glycol / Q000737:chemistry*; D008968:Molecular Conformation; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000473:Alkanes; D013438:Sulfhydryl Compounds; D019855:Ethylene Glycol