Solvo-hydrothermal growth and photoluminescence studies of micro and nano structured Zinc Sulfide for bio-imaging applications Thesis submitted to COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY in partial fulfillment of the requirements for the award of the degree of DOCTOR OF PHILOSOPHY in Physics by Sajan P. Nano Functional Materials Lab Department of Physics Cochin University of Science and Technology Cochin - 682 022, Kerala, India June 2016