•      Nanoparticles: This is a research project with significant educational components and undergraduate student involvement that will study the physical mechanisms of laser assisted modification of two types of nanoparticles: three dimensional, almost spherical metal nanoparticles embedded in dielectric matrices and highly anisotropic one- dimensional structures confined into carbon nanotubes.This study combines the data obtained from UV-VIS absorption spectroscopy and numerical Mie resonance analysis, with material characterization performed by Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results of the investigation will have two-fold significance. First, they will contribute new important information in the area of nanosized particles with the key goal of tailoring their properties. Second, the study will serve as an effective educational tool for teaching undergraduate students how ‘real life’ research in an international setting is conducted.

• ·      Raman Spectroscopy in Art and Archeology: Micro Raman spectroscopy is applied for mineralogical characterization of Bronze Age Cypriot ceramic fragments from the Lapatsa Tomb collection of The Ringling Museum of Art. Various phases have been identified. The presence of low temperature albite, and anatase suggests low firing temperature. The presence of hematite suggests firing in oxidizing atmosphere. On-site fiber Raman probe spectroscopy is applied for pigment and glaze characterization of three Luca Della Robbia majolica terracotta reliefs:  Madonna and Child ( 33” x 23“), Saint John the Baptist (29”tondo) and  Adoration (28” tondo). A celebrated pioneer of the artistic Renaissance, Luca Della Robbia experimentally developed and perfected the art of glazed terracotta.  Much of the success of the Della Robbia art form can be attributed to the mastery of colors and effects produced in the artworks' glazes, with the signature sign of a Della Robbia being white "porcelain like" relief figures on top of a blue back ground. The art pieces are exhibited in one of the galleries of The Ringling Museum of Art. The Raman signatures of the white, blue, yellow and green pigments will be studied and compared. In addition, spectra will be collected from areas on the surface where the glaze has been chipped away. The mineralogical composition of the clay material will be determined. With the data provided by Raman spectroscopy, these works will benefit in art historical context and conservation information.

• ·      Thin Film Mechanics: The problem of crack pattern formation has theoretical as well as practical significance in mechanics, physics, and chemistry of materials and can be a subject of study in the physics of self-organizing phenomena as well.  In a controlled and reproducible manner we are able to create four distinct types of crack patterns  - straight line cracks, curved closed loop cracks crescent (sawtooth) periodic cracks, and spiral cracks. Through these experiments we find a relationship between the geometrical parameters of the cracks and some of the properties of the films. We suggest a phenomenological explanation based on the film warping due to the stress nonuniformity created in the drying stage of the sol-gel materials.

• ·      Thin Metal Films: Chromium - Nickel alloys are widely used for fabrication of discrete thin film resistors in hybrid microelectronics. In the last twenty years extensive research is carried on the structural and electrical properties of stable nichrome thin films. In this project Atomic force microscopy (AFM) topography imaging is used to investigate: a) surface roughness of  two types of stainless steel substrates with surfaces finished by different finishing processes;  and  b) the change of the surface roughness following  SiO₂  film deposition onto the stainless steel  substrates.  The surface roughness is characterized by the following statistical parameters: average surface height, interface width, lateral correlation length and roughness exponent. The sheet resistance and the temperature coefficient of resistance (TCR) of thin NiCr film, deposited by RF magnetron  sputtering onto the stainless steel/SiO₂ substrates are measured and related to the surface roughness parameters of the film.  Direct proportionality between the measured sheet resistance of the films deposited at identical deposition conditions and the area under the height distribution function of their surfaces is found. The project is in collaboration with the Pressure Sensor Division of Stone Ridge Corp.

• ·     Carbon Nanotubes: In view of the recent progress in nanophysics and nanotechnologies the ability to assemble individual nanotubes and to organize them in the desired structures becomes more important. Multi-wall carbon nanotubes (MWCNTs) dispersed on polymer film are rotated and aligned with linearly polarized radiation from Nd:YAG laser operating at its fourth harmonic, 266 nm. This process is explained by the interaction of the strong electric field of the radiation with the highly anisotropic polarizability of the carbon nanotubes. The nanotube alignment is examined by Atomic Force Microscope (AFM).  Raman spectroscopy study of filled double walled CNT. Raman Spectroscopy study of Carbon Nanotubes. The Raman Spectroscopy study of his samples is carried out in my laboratory at New College. PbI₂-filled double-walled carbon nanotubes (PbI₂@DWCNT) are studied by Raman spectroscopy employing 785 nm excitation wavelength and their spectra are compared to those of pristine DWCNT.

•      Laser induced submicron periodic structures on polymer surfaces: Interesting phenomenon both from     theoretical and practical standpoints is the self organizing process of formation of one and two dimensional periodic structures (surface relief) on polymer surfaces induced by polarized laser radiation. Materials, process parameters, photo-physical and thermo-physical aspects of laser-matter interactions, as well as the optical and electrical properties of the modified surfaces are the subject of my research.
   

Website Designed by Vesta