ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Filtering by
- All Subjects: Biochemistry
- All Subjects: Tunneling (Physics)
- Creators: Mujica, Vladimiro
This dissertation presents results towards this end, including the successful implementations of the first diffusive mixing chemoactivated reactions and ultrafast dynamics in the femtosecond regime. The primary focus is on photosynthetic membrane proteins and enzymatic drug targets, in pursuit of strategies for sustainable energy and medical advancement by gaining understanding of the structure-function relationships evolved in nature. In particular, photosystem I, photosystem II, the complex of photosystem I and ferredoxin, and 3-deoxy-D-manno-2-octulosonate-8-phosphate synthase are reported on, from purification and isolation, to crystallogenesis, to experimental design and data collection and subsequent interpretation of results and novel insights gained.
that arises in the response of a molecule to an external electric field. To illustrate
the plausibility of the idea, we used Simmons' tunneling model, which describes image
charge and dielectric effects on electron transport through a barrier. In such a
model, the barrier height depends on the dielectric constant of the electrode-molecule-electrode junction, which in turn can be approximately expressed in terms of the
molecular polarizability via the classical Clausius-Mossotti relation. In addition to
using the tunneling model, the validity of the relationships between the molecular
polarizability and the molecular conductance was tested by comparing calculated
and experimentally measured conductance of different chemical structures ranging
from covalent bonded to non-covalent bonded systems. We found that either using
the tunneling model or the first-principle calculated quantities or experimental data,
the conductance decreases as the molecular polarizability increases. In contrast to
this strong correlation, our results showed that in some cases there was a weaker or
none correlation between the conductance and other molecular electronic properties
including HOMO-LUMO gap, chemical geometries, and interactions energies. All
these results together suggest that using the molecular polarizability as a molecular
descriptor for conductance can offer some advantages compared to using other
molecular electronic properties and can give additional insight about the electronic
transport property of a junction.
These results also show the validity of the physically intuitive picture that to a first
approximation a molecule in a junction behaves as a dielectric that is polarized in the
opposite sense of the applied bias, thereby creating an interfacial barrier that hampers
tunneling. The use of the polarizability as a descriptor of molecular conductance offers
signicant conceptual and practical advantages over a picture based in molecular
orbitals. Despite the simplicity of our model, it sheds light on a hitherto neglected
connection between molecular polarizability and conductance and paves the way for
further conceptual and theoretical developments.
The results of this work was sent to two publications. One of them was accepted
in the International Journal of Nanotechnology (IJNT) and the other is still under
review in the Journal of Physical Chemistry C.