title: Inelastic tunneling spectroscopy of alkanethiol molecules: high-resolution spectroscopy and theoretical simulations.
abstract: We investigate inelastic electron tunneling spectroscopy (IETS) for alkanethiol self-assembled monolayers (SAM) with a scanning tunneling microscope and compare it to first-principles calculations. Using a combination of partial deuteration of the molecule and high-resolution measurements, we identify and differentiate between methyl (CH3) and methylene (CH2) groups and their symmetric and asymmetric C-H stretch modes. The calculations agree quantitatively with the measured IETS in producing the weight of the symmetric and asymmetric C-H stretch modes while the methylene stretch mode is largely underestimated. We further show that inelastic intermolecular scattering is important in the SAM by plotting the theoretical current densities.
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai, 980-8577, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Okabayashi
authors.forename: Magnus
authors.initials: M
authors.lastname: Paulsson
authors.forename: Hiromu
authors.initials: H
authors.lastname: Ueba
authors.forename: Youhei
authors.initials: Y
authors.lastname: Konda
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Komeda