NOVEL SPECTROSCOPIC INSTRUMENTATION AND SPECTROSCOPIC STUDIES ON BIOLOGICALLY IMPORTANT MOLECULES AND CRYSTALS

Abstract

Many human, plant, and animal diseases, especially those caused by pathogens such as bacteria are hard to detect in early stages. Current gold standard of identifying live/dead bacteria and bacteria strains is culturing, which involve plating bacteria on agar plates and incubating them for ~ 24 hours and subsequently counting colonies. One major drawback of culturing technique is that it requires a large amount of time during which infections can grow multiple folds and may be fatal. The research conducted here developed new techniques and instrumentation for accomplishing this task of determining live/dead bacteria and bacteria strains, in-situ within minutes. These new techniques and instrumentation make use of optical spectroscopy techniques such as Raman spectroscopy, resonance Raman spectroscopy and Fluorescence spectroscopy. The novel instruments developed in this research utilize common detector systems such as monochrome CCTV cameras and cellphone cameras to make optical spectroscopy detection ubiquitously available. Along with optical instrumentation for pathogen detection, upconverting nano-particles and fluorescent molecules based optical systems are developed to enable human eye to see in the near infrared and near ultraviolet light. Alongside, femtosecond to millisecond time resolved absorption studies are conducted on visual pigments and their photo-intermediaries are identified. Steady state and time-resolved X-ray diffraction studies are conducted on single crystal Nickle to understand how its crystal structure changes as a function of pulsed heating, especially around the Curie temperature where magnetic properties change from ferromagnetic to paramagnetic.