Determining the Orientation of Chemical Functional Groups on Metal Surfaces by a Combination of Homodyne and Heterodyne Nonlinear Vibrational Spectroscopy
Date
2017
Authors
Yang, Wei-Chen
Hore, Dennis K.
Journal Title
Journal ISSN
Volume Title
Publisher
The Journal of Physical Chemistry C
Abstract
We illustrate how phase-sensitive sum-frequency generation spectroscopy may be used to determine the polar orientation of organic species on metals, where there is a significant electronic contribution to the second-order signal. It turns out that traditional direct heterodyne schemes, as would be applied to the same molecules on dielectric substrates, are challenging to use here as a result of the large resonant/nonresonant amplitude ratio that diminishes the phase contrast observed in tuning through the vibrational mode. This is demonstrated in a variety of experimental surfaces that illustrate all limiting cases. We propose a scheme that can overcome this challenge and thereby determine the chemical functional group orientation through a combination of the homodyne spectrum and some phase information from a heterodyne approach.
Description
Keywords
Metals, Nonlinear optics, Oscillation, Polarity Alkyls
Citation
Yang, W. & Hore, D. K. (2017). Determining the orientation of chemical functional groups on metal surfaces by a combination of homodyne and heterodyne nonlinear vibrational spectroscopy. The Journal of Physical Chemistry C, 121(50), 28043- 28050. DOI: 10.1021/acs.jpcc.7b09730