Date of Publication

10-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Physics

Subject Categories

Quantum Physics

College

College of Science

Department/Unit

Physics

Thesis Adviser

Nelson B. Arboleda, Jr.

Defense Panel Chair

Michelle T. Natividad

Defense Panel Member

Christopher Que
Maria Carla F. Manzano
Joaquin Moreno
Allan Padam

Abstract/Summary

Carbon monoxide (CO) is a common air pollutant in the environment but at the same time an important reactant to a number of industrial catalytic processes. In hydrogen production, through water gas shift process, surface pre-adsorbed CO is needed to reduce water to hydrogen gas. In Boudouard reaction, adsorbed CO molecules oxidize to CO2, a lesser harmful gas, and leaves residual carbon on the surface for the production of carbon based materials such as graphite etc. These show the importance of understanding the interaction mechanism of CO on metal surfaces. In this study, we present the adsorption, diffusion and rotation of CO on Cu(410) stepped copper surface. We used a wide terraced, stepped surface for our investigation due to the fact that surface atoms of Cu(410), with their varying coordination number, may serve as a representation of defects on metal surfaces. Here we show that CO is sensitive to atomic coordination and surface corrugation. We show this through the preferential adsorption of CO on low coordinated step sites and its weaker adsorption towards the valley site of a stepped surface. This anisotropy that arise due to the asymmetric geometry across the step and the valley allows for diffusion of CO towards the step site. By monitoring the change in the vibrational frequency of CO as it translates across the surface we found that it manifests the atomic corrugation of the Cu(410) surface. We also show that at the first surface layer (step edge site) of Cu(410) rotational state dependence of adsorption probability exist. The results obtained and analyzed from this work can contribute to our current understanding of surface-adsorbate interaction. Most importantly, this work suggests the possibility of monitoring the excitation in the internal degrees of freedom of CO to obtain information on the surface structure.

Abstract Format

html

Language

English

Format

Electronic

Physical Description

69 leaves

Keywords

Carbon monoxide; Copper—Surfaces

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Embargo Period

5-28-2022

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