Thesis
Unconventional adsorption of alkane substituted naphthalene diimides on highly ordered pyrolytic graphite
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/103637
Abstract
Scanning Tunneling Microscopy (STM) is reported for N, N'-Dihexyl-1,8:4,5 naphthalenediimide (C6 NDI), N, N'-Dioctyl-1,8:4,5-naphthalenediimide (C8 NDI), and N, N'-Didodecane-1,8:4,5-naphthalenediimide (C12 NDI) adsorbed on highly ordered pyrolytic graphite (HOPG). All three naphthalenediimides (NDI) formed well ordered monolayers at the interface between the HOPG and different alkylbenzenes. C8 NDI was also adsorbed from toluene at both the HOPG-air and HOPG-vacuum interface. Planar adsorption of the C6, the C8 and C12 NDI ring cores on HOPG was observed. All three NDIs were observed to have the same monolayer structure, but in order to fit them to the structure, their alkane arms were at an angle to the NDI ring core which lay flat relative to the surface of the HOPG. Hydrogen bonding, O and N interaction with HOPG, and [pi pi] interactions all appear to play a primary role in the creation of the monolayer structure. The monolayer structure had no dependence on the adsorption method and was stable. Other alkane substituted systems in previous studies which form adsorbate structures on graphite are driven by alkane chain interactions with HOPG and interdigitation. The observed unit cell for C6 NDI has a= 2.11±0.04 nm, b= 1.75±0.14 nm, and [alpha]= 67.02±2.39°. The observed unit cell for C8 NDI in solution has a= 1.98±0.25 nm, b= 1.73±0.25 nm, and [alpha]= 68.00±2.00°. The observed unit cell for C8 NDI cast films in UHV is a=1.97 ± 0.20 nm, b=1.95 ± 0.20 nm, and [alpha]= 66.00 ± 2.00º. The observed unit cell for C12 NDI has a=1.95 ± 0.10 nm, b=1.93 ± 0.09 nm, and [alpha]=72.60 ± 2.60º. The STM imaging is highly dependent on the bias and appears to be controlled by an unoccupied orbital in the ±2 V bias region. Orbital mediated tunneling spectroscopy (OMTS) was performed on C8 NDI. The spectra revealed a single electron affinity band near 3.5 eV below the vacuum level.
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Details
- Title
- Unconventional adsorption of alkane substituted naphthalene diimides on highly ordered pyrolytic graphite
- Creators
- Clarisa Michelle Carrizales
- Contributors
- Kerry W. Hipps (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemistry, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525393901842
- Language
- English
- Resource Type
- Thesis