Infrared Diagnostics on Micro and Nano Scale Structures

Fourier Transform Infrared spectroscopy is used as a diagnostic tool in biological and physical sciences by characterizing the samples based on infrared light-matter interaction. In the case of biological samples, Activation of Jurkat T-cells in culture following treatment with anti-CD3 (Cluster of Differentiation 3) antibody is detectable by interrogating the treated T-cells using the Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) Spectroscopy technique. Cell activation was detected within 75 minutes after the cells encountered specific immunoglobulin molecules. Spectral markers noted following ligation of the CD3 receptor with anti CD3 antibody provides proof-of-concept that ATR-FTIR spectroscopy is a sensitive measure of molecular events subsequent to cells interacting with anti-CD3 Immunoglobulin G (IgG). ATR-FTIR spectroscopy is also used to screen for Colitis in chronic (Interleukin 10 knockout) and acute (Dextran Sodium Sulphate-induced) models. Arthritis (Collagen Antibody Induced Arthritis) and metabolic syndrome (Toll like receptor 5 knockout) models are also tested as controls. The marker identified as mannose uniquely screens and distinguishes the colitic from the non-colitic samples and the controls. The reference or the baseline spectrum could be the pooled and averaged spectra of non-colitic samples or the subject’s previous sample spectrum. The circular dichroism of titanium-doped silver chiral nanorod arrays grown using the glancing angle deposition (GLAD) method is investigated in the visible and near infrared ranges using transmission ellipsometry and spectroscopy. The characteristics of these circular polarization effects are strongly influenced by the morphology of the deposited arrays. Studies of optical phonon modes in nearly defect-free GaN nanowires embedded with intrinsic InGaN quantum dots by using oblique angle transmission infrared spectroscopy is described here. These phonon modes are dependent on the nanowire fill-factor, doping densities of the nanowires and the presence of InGaN dots. These factors can be applied for potential phonon based photodetectors whose spectral responses can be tailored by varying a combination of these three parameters. The optical anisotropy along the growth (c-) axis of the GaN nanowire contributes to the polarization agility of such potential photodetectors