Tandem mass spectrometry and surface enhanced Raman spectroscopy for examining ion-surface and molecule-surface interactions
Abstract
Interactions of ions and molecules with surfaces were studied in both gas (especially vacuum) and electrochemical environments. In the vacuum environment, a hybrid BEEQ tandem mass spectrometer was used to study hyperthermal ion/surface collision processes. The nature of the process at low impact collision energies (typically <10 >eV) and the preparation of chemically modified surfaces using such “soft-landing” processes were explored. It was shown that polyatomic ions can be deposited into fluorinated self-assembled monolayer (F-SAM) surfaces where they can survive for extended periods (up to several days) in and out of the vacuum. Vibrational characterization of chemisorbed species and reaction products on silver, gold and Pt-group surfaces, the latter prepared by ultrathin film electrodeposition onto gold (“overlayer SERS”), has been explored using surface-enhanced Raman spectroscopy (SERS) in electrochemical and gas-phase environments. The virtue of SERS for probing metal-adsorbate interactions was demonstrated by accessing the coordination modes of a model polyatomic adsorbate, thiocyanate. The “overlayer SERS” strategy was also used to elucidate the effect of water vapor on the temperature-dependent surface oxidation of Pt-group metals in gaseous oxygen. These findings provide a direct link between metal surface oxidation in electrochemical and ambient gaseous environment. A versatile spectroelectrochemical flow cell was developed to facilitate studies of reaction and other adsorptive processes in electrochemistry. Specifically, the adsorption kinetics of simple ions and molecules on silver and rhodium surfaces and the mechanism of formic acid electrooxidation on rhodium film electrodes were examined. Surface Raman spectroscopy was also used to characterize bismuth oxide films electrochemically deposited on gold substrates.
Degree
Ph.D.
Advisors
Weaver, Purdue University.
Subject Area
Analytical chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.