Experimental and quantum calculation of molecular systems of biological and chemical importance by Raman, infrared and SERS

Abstract

Study of interaction of light with matter is a subject of molecular spectroscopy. Theories developed by Maxwell, Young and other scientists in the nineteenth century established that light could be thought as an electromagnetic wave propagating in a medium. Interaction of such wave with molecules can provide rich information about their structure as well as physical and chemical properties. The energy of a fixed molecule can be divided into three parts: electronic, vibrational and rotational. Vibrational spectroscopy probes the vibrational energy levels of a molecule. With the advent of modern optical instrumentation, it has become an indispensable characterization technique in natural science today. Infra-red (IR) and Raman are two main techniques in vibrational spectroscopy. Although both techniques probe the vibrational energy level of a molecule, physical mechanism involved in these processes is different as will be described later. Of these two techniques, mainly Raman spectroscopy is employed in this work.