Resume

• 2011

  Doctor of Philosophy (Ph.D.)

  Dissertation: Structural

  Electronic

  and Magnetic Properties of Graphene-Based Nanomaterials.

  Physical Organic Chemistry

  Clark Atlanta University

• 2008

  Sinhalese

  English

  Master of Science (M.S.)

  Thesis: Structural and Electronic Properties of Hydrogenated Graphene.

  Computational Physics

  Clark Atlanta University

• 2005

  Master of Science (M.Sc.)

  Thesis: Design and Construction of a Testing Machine to Study the Impact Behavior of Materials.

  Physics of Materials

  University Hockey Team

  University of Peradeniya

• 2001

  Bachelor of Science (B.Sc.)

  Was a member of the university hockey team which won the \"Inter University Hockey Championship\" in 2001.\nToured India by representing the university hockey team in 2002.\n

  Physical Sciences

  University of Peradeniya

• Berry College - Duminda Samarakoon

  Berry College is an independent

  coeducational college with fully accredited arts

  sciences and professional programs plus specialized graduate programs in education and business administration. The college is recognized nationally for the quality and value of its educational experience.

  Physics

  Research

  Graphene and Carbon Nanotubes

  Chemistry

  Nanotechnology

  Laboratory

  Science

  Materials

  Multiscale Modeling and Simulations of Nanoscopic Materials

  Simulations

  Teaching

  Quantum Chemistry and Condensed Matter Physics

  Nanomaterials

  Structural and Electronic Properties Of Fluorographene

  The structural and electronic characteristics of fluorinated graphene are investigated based on first-principles density-functional calculations. A detailed analysis of the energy order for stoichiometric fluorographene membranes indicates that there exists prominent chair and stirrup conformations

  which correlate with the experimentally observed in-plane lattice expansion contrary to a contraction in graphane. The optical response of fluorographene is investigated using the GW–Bethe–Salpeter equation approach. The results are in good conformity with the experimentally observed optical gap and reveal predominant charge-transfer excitations arising from strong electron–hole interactions. The appearance of bounded excitons in the ultraviolet region can result in an excitonic Bose–Einstein condensate in fluorographene.

  Structural and Electronic Properties Of Fluorographene

  We have investigated the structural and electronic characteristics of fully hydrogenated boron-nitride (BN) layer and zigzag-edged nanoribbons using dispersion-corrected density-functional calculations. In the fully hydrogenated BN structure

  the hydrogen atoms adsorb on top of the B and N sites

  alternating on both sides of the hexagonal BN-plane in a specific periodic manner. Among various low-energy hydrogenated membranes referred to as chair

  boat

  twist-boat

  and stirrup

  the stirrup conformation is the most energetically favorable one. The zigzag-edged BNnanoribbon

  prominently fabricated in experiments

  possesses intrinsic half-metallicity with full hydrogenation. The half-metallicity can be tuned by applying a transverse electric bias

  thereby providing a promising route for spintronics device applications.

  Intrinsic Half-Metallicity in Hydrogenated Boron-Nitride Nanoribbons

  Hydrogenated epitaxial graphene has distinctive electronic properties compared to the two-sided hydrogenated graphene referred to as graphane. Of particular interest is the experimentally observed room-temperature ferromagnetic semiconducting property

  which has remained elusive to theoretical interpretation. Here

  we present results of a density functional theory investigation into various hydrogenation patterns. Our results indicate that the stability of a given hydrogenation pattern is strongly influenced by the amount of sp2-hybridized bonding in the structures. A hydrogenation pattern with a trigonal planar network is identified as an intrinsic ferromagnetic semiconductor

  which is in very good conformity with experimental observations. Our results provide insight into the structural

  electronic

  and magnetic properties of hydrogenated epitaxial graphene.

  Trigonal Hydrogenated Epitaxial Graphene: A Ferromagnetic Semiconductor

  We use a combination of computational and experimental studies to elucidate the effect of polymer stereoregularity on the capability of polystyrene interacting with single-walled carbon nanotube (SWNT) surfaces. Calculated binding energies on complexes of slightly oxidized SWNT with isotactic and atactic polystyrene favor the former

  which suggests that the isotactic polymer interacts more effectively with the SWNT. The glass transition temperature (Tg) of the isotactic polystyrene/SWNT matrix increases from 90.9 to 100.5 °C as the SWNT content is increased to 0.5%

  whereas the glass transition temperature of the atactic polystyrene/SWNT matrix is invariant with increasing SWNT content. Rotating frame 13C T1ρ relaxation rates for the isotactic polymer/SWNT matrix increases from 2.15 to 2.43 ms as the SWNT content is increased from 0.25 to 1.0%. However

  the rotating frame 13C T1ρ relaxation rates for the atactic polymer/SWNT matrix decreases from 2.50 to 1.60 ms as SWNT content is increased from 0.25 to 1.0%. Our results demonstrate that the SWNTs are better dispersed within the isotactic polystyrene and the better dispersion is associated with a more effective interaction of the isotactic polymer with the SWNT surface.

  Effect of polymer stereoregularity on polystyrene/single-walled carbon nanotube interactions

  We have studied the electronic characteristics of multilayer epitaxial graphene under a perpendicularly applied electric bias. Ultraviolet photoemission spectroscopy measurements reveal that there is notable variation of the electronic density-of-states in valence bands near the Fermi level. Evolution of the electronic structure of graphite and rotational-stacked multilayer epitaxial graphene as a function of the applied electric bias is investigated using first-principles density-functional theory including interlayer van der Waals interactions. The experimental and theoretical results demonstrate that the tailoring of electronic band structure correlates with the interlayer coupling tuned by the applied bias. The implications of controllable electronic structure of rotationally fault-stacked epitaxial graphene grown on the C-face of SiC for future device applications are discussed.

  Tunable Bands in Biased Multilayer Epitaxial Graphene

  Graphane is a two-dimensional system consisting of a single planar layer of fully saturated carbon atoms

  which has recently been realized experimentally through hydrogenation of graphene membranes. We have studied the stability of chair

  boat

  and twist-boat graphane structures using first-principles density functional calculations. Our results indicate that locally stable twist-boat membranes significantly contribute to the experimentally observed lattice contraction. The band gaps of graphane nanoribbons decrease monotonically with the increase of the ribbon width and are insensitive to the edge structure. The implications of these results for future hydrogenated graphene applications are discussed.

  Chair and Twist-Boat Membranes in Hydrogenated Graphene

  We have investigated the structural

  electronic

  and vibrational properties of graphene oxide based on first-principles density-functional calculations. A twist-boat conformation is identified as the energetically most favorable nonmetallic configuration for fully oxidized graphene. The calculated Raman G-band blue shift is in very good agreement with experimental observations. Our results provide important insight into structural and electronic characteristics that are useful for further development of graphene-based nanodevices.

  Twist-Boat Conformation in Graphene Oxides

  We have studied the electronic structural characteristics of hydrogenated bilayer graphene under a perpendicular electric bias using first-principles density functional calculations. The bias voltage applied between the two hydrogenated graphene layers allows continuous tuning of the band gap and leads to transition from semiconducting to metallic state. Desorption of hydrogen from one layer in the chair conformation yields a ferromagnetic semiconductor with a tunable band gap. The implications of tailoring the band structure of biased system for future graphene-based device applications are discussed.

  Tunable Band Gap in Hydrogenated Bilayer Graphene

  Fluorinated epitaxial graphene has potential applications in organic electronics. We present the calculation results by means of first-principles density-functional-theory for various fluorination patterns. Our results indicate that semi-fluorinated graphene conformations follow the same energetic order as the corresponding hydrogenated graphene counterparts. The distinctive electronic properties between semi-hydrogenated graphene and semi-fluorinated graphene are attributed to the polar covalent C–F bond in contrast to the covalent C–H bond. The partial ionic character of the C–F bond results in the hyperconjugation of C–F σ-bonds with an sp2 network of graphene. Resonant orbitals stabilize the stirrup conformation via the gauche effect. Resonant orbitals also lead to electron doping of the sp2 network and enhanced excitonic effect. The implications of resonant-orbital-induced doping for the electronic and magnetic properties of fluorinated epitaxial graphene are discussed.

  Resonant orbitals in fluorinated epitaxial graphene

  Samarakoon

  Ph.D.

  Duminda

  Augusta University

  Berry College

  Cornell University

  PARADIM Theory User Facilit

  Rome

  GA

  Teaching lectures and laboratory sections of introductory chemistry courses.\nSupervising students to conduct biomolecular simulations of DNA-binding proteins.

  Visiting Assistant Professor in Chemistry

  Berry College

  Ithaca

  New York Area

  Visiting Scientist

  Cornell University

  PARADIM Theory User Facilit

  Augusta University

  Augusta

  Georgia Area

  Lecturer In Chemistry