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Physics Colloquium: Morphology Dependent Excited States in Conjugated Polymers AND From Proto-Galactic Clouds to Planets in Tight Binary Stellar Systems
Wednesday, Aug. 28, 2019
4 p.m. - 5 p.m. Location: SLC 1.102

The two new UTD Senior Lecturers in Physics will present their research:

Morphology Dependent Excited States in Conjugated Polymers

Dr. Amena Khan (UT Dallas)

Organic semiconductors possess the electronic properties of traditional semiconductors and at the same time exploit the mechanical flexibility of plastics. Conjugated polymers are a class within it that has attracted the semiconductor industry due to its prospect of low-cost large-area production, color tunability, low operating voltage; these properties make them low in energy consumption and environment-friendly. Unlike conventional inorganic semiconductors, however, the photophysics of the organic semiconductors is defined by strong phonon coupling to the electronic transition. Furthermore, where the addition of functional groups to the main polymer backbone in conjugated polymers can be crucial to increase solubility (to facilitate inkjet printing, for example), the added complex roles of the different components of the polymer chain can affect the optoelectronic properties in the film. In this talk, I will present some of the work I have done to understand emissive properties from the blue-emitting polyfluorenes that have found applications in organic light-emitting diodes, transistor, and lasers. I will discuss the role of film morphology and how chain conformation determines the number of emissive states, both singlet and triplet, and energy transfer mechanisms.

Numerical Simulations of Astrophysical Systems:
From Proto-Galactic Clouds to Planets in Tight Binary Stellar Systems

Dr. Lamya Saleh (UT Dallas)

I will discuss two publications that represent best my professional training in research.  My doctoral thesis was based on hierarchical models of Galaxy formation including cold dark matter cores with the goal of explaining the observed dynamical and metallicity trends in our galaxy.  Using numerical simulations, pre-galactic primordial clouds were evolved with chemical enrichment and energy input by type II and type Ia supernovae, a supernova induced star formation mechanism, and metallicity dependent ejecta taking into consideration the finite lifetimes of stars.  Our model traced relative chemical abundances of alpha- and Fe-group elements in the galaxy down to metallicities as low as [Fe/H] ~ -4, reasonably agreeing with observed trends.  As a postdoctoral trainee, I was interested in investigating the dynamical stability of planetary systems with S-type orbits within tight binary systems. This was triggered by the surprising discoveries of several such systems at the time.  Dynamical integrations of four-body systems were performed including planet-planet interactions, Kozai oscillations, and GR effects.  We investigated stability zones and were able to reproduce observed eccentricity trends by the onset of Kozai oscillations in such systems.

Contact Info:
Michael Kesden, 972-883-3598
Questions? Email me.

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