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Type of Document Master's Thesis Author Sun, Peng Author's Email Address psun@nd.edu URN etd-04162004-122454 Title Xps Study of Neutral Mixed Valence Ru Dimer: [(acac)2Ru]2(Bpz4) and Afm Study of Water Meniscus Between an Afm Tip and Nacl Substrate Degree Master of Science Department Chemistry and Biochemistry Advisory Committee
Advisor Name Title Marya Lieberman Committee Chair S. Alex Kandel Committee Member Thomas P. Fehlner Committee Member Keywords
- water meniscus
- AFM
- XPS
- mixed valence
Date of Defense 2004-04-16 Availability unrestricted Abstract This thesis consists of two parts. In the first part, X-ray photoelectron spectroscopy (XPS) was used to study a new neutral mixed valence complex: [((acac)2Ru)2B(pz)4]. XPS study of the a powder sample of the Ru dimer indicated only one group of Ru signals with binding energies close to those of RuIII in Creutz-Taube-type complexes, which suggested that the Ru dimer used was possibly oxidized RuIII/RuIII during the experiment. Surface attachment of the Ru dimer was measured on self-assembled monolayers of alkanethiols with various terminal groups. Contact angle, ellipsometry and XPS measurements suggested that the Ru dimer molecules form self-limiting monolayers on hydrophilic surfaces and not bind detectably to hydrophobic surface. Additionally, an anchoring group 4-mercaptopyrazole was studied by XPS, demonstrating that the adsorption of the molecules on gold surface is self-limiting.
In the second part, water meniscus condensed between an AFM tip and a NaCl substrate was studied in various conditions, including ambient, dry nitrogen and ultra-high vacuum (UHV). Water meniscus formation was measured by probing the ability of the meniscus to dissolve the NaCl near the contact point and evaluating the pull-off point as a function of water partial pressures. These studies are consistent with the formation of water meniscus under ambient and dry conditions.
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