TitleMetallic quantum well states and chemisorption
NameTskipuri, Levan (author), Bartynski, Robert (chair), Andrei, Eva (internal member), Gilman, Ronald (internal member), Vescovo, Elio (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectPhysics and Astronomy,
DescriptionIn this thesis the adsorption properties of carbon monoxide (CO) on the epitaxial fcc-Co/Cu(100), Ni/Cu (100) and Cu/fcc-Fe/Cu(100) systems are reported.
The fcc-Co/Cu(100), Ni/Cu(100) systems are known to exhibit metallic quantum well (MQW) states at energies 1 eV or greater above the Fermi level, that disperse upward with increasing film thickness, but never cross the Fermi level and are less pronounced than MQW features in Cu/fcc-Fe/Cu(100) system. The presence of quantum size effects in electronic structure of these systems gives a possibility to modify molecule-surface interactions and influence CO adsorption. All these systems were explored with low energy electron diffraction (LEED), inverse photoemission (IPE), infrared absorption (FTIR) Spectroscopy and temperature programmed desorption (TPD).
TPD measurements revealed several desorption features upon CO adsorption on The fcc-Co/Cu(100), Ni/Cu(100) systems. These TPD features are linked
to the corresponding modes in IR spectra and suggest a range of bonding configurations at Co and Ni surfaces. The analysis of TPD and FTIR spectra are given. The adsorption properties of these thin film surfaces are compared to those of single crystal hcp-Co and Ni(100).
For increasing thickness of Cu on the fcc-Fe/Cu system, MQW states periodically cross and modulate IPE intensity at Fermi level. Changes in the peak temperature of TPD spectra are correlated with these modulations of IPE intensity. IR shows two features in the CO stretch frequency spectra, which are identified as CO adsorbed on terrace sites and at step sites. The IR results also suggest a correlation between intensities of these two spectral features and MQW states crossing the Fermi level.
The results of measurements done on the dimethyl disulfide (DMDS) molecule adsorbed on the Cu/fcc-Fe/Cu(100) MQW system is also reported. DMDS is
a simple example of an organic thiol, a class of molecules that exhibit self-assembly properties on metal surfaces. The measurements suggest possible modifications of molecular adsorption on the Cu surface. Similarities and differences of DMDS molecule adsorption on thin film Cu(100) and single crystal Cu(100) will be discussed.
NoteIncludes bibliographical references (p. 123-130)
Noteby Levan Tskipuri
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work