Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form

I. Theory of Laser Driven Molecular Wires.II. Light Diffraction by Colloidal Crystals - Numerical Simulations for Realistic Finite Systems Using Single Scattering Theory.

Tikhonov, Alexander (2007) I. Theory of Laser Driven Molecular Wires.II. Light Diffraction by Colloidal Crystals - Numerical Simulations for Realistic Finite Systems Using Single Scattering Theory. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

Primary Text

Download (2MB) | Preview


Part I considers electron transport through a molecular bridge coupled to two metal electrodes in the presence of a monochromatic ac radiation field. Coherent current flow through the wire is calculated within a nondissipative one-electron tight binding model of the quantum dynamics. Using Floquet theory, the field-driven molecular wire is mapped to an effective time- independent quantum system characterized by a tight-binding Hamiltonian with the same essential structure as the nondriven analog. Thus, the Landauer formalism and scattering Green's Function methods for computing current flow through the wire, which have been profitably applied to the molecular wire problem in the absence of driving, can also be used to analyze the corresponding field-driven system.The theory developed here is applied to an experimentally relevant system, namely a xylyl-dithiol molecule in contact at either end with gold electrodes. Net current through the wire is calculated for two - STM and molecular junction - configurations of the electrode-wire-electrode system for a range of experimental inputs, including bias and the intensity and frequency of the laser. Via absorption/emission of photons, the electron tunneling occurs through an interference of many pathways and may lead to a significantly enhanced laser-driven current at experimentally accessible laser field strengths.In Part II we apply a single particle scattering methodology to calculate diffraction efficiencies of finite Crystalline Colloidal Arrays (CCA's). We developed an extension of the well-known Kinematic theory and tested it by comparing computed light scattering efficiencies with exact results for 1D slab model. We discuss some applications of the method to finite CCA's of different shapes and sizes. In particular, the dependence of diffraction intensities on the incident angle is analyzed near the Bragg diffraction maximum for several different crystal planes. We also study the effect of the incident beam shape and cross sectional profile on the CCA diffraction. Finally, the effective penetration depth for the incident light is calculated and compared for several incident directions, and the effect of stacking faults on diffraction efficiencies is analyzed using the methodology developed herein.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairCoalson, Robrob@mercury.chem.pitt.eduROBC
Committee MemberPetek, Hrvojepetek@pitt.eduPETEK
Committee MemberJordan , Kennethken@visual1.chem.pitt.eduJORDAN
Committee MemberAsher, Sanfordasher@pitt.eduASHER
Date: 29 January 2007
Date Type: Completion
Defense Date: 27 October 2006
Approval Date: 29 January 2007
Submission Date: 16 November 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: molecular electronics; nanoscale transport junction; photonic crystals; driven electronic transport; driven tunneling
Other ID:, etd-11162006-140646
Date Deposited: 10 Nov 2011 20:05
Last Modified: 15 Nov 2016 13:51


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item