Adsorption of adenine and phenylglycine on Cu(110) surfaces studied using STM and RAIRS

Abstract

The adsorption of biologically active molecules, such as the DNA bases, amino acids, on solid surfaces has been the subject of a number of experimental and theoretical studies in the past years. The understanding of the self-assembly mechanism of bioactive molecules on surfaces not only is fundamentally important in the preparation of bioactive surfaces, but also provides us insight into the origins of life and homo-chirality in nature. In this thesis, the adsorption behaviour of adenine and phenylglycine molecules on the Cu(110) surface has been investigated in order to understand the effect of experimental parameters like coverage, annealing temperature etc. on the molecular orientation and the ordering of the adlayer structures. The thesis is organised in six parts: Chapter I gives an introduction to the relevance of surface sciences studies, describing the phenomena of surface chirality and molecular adsorption behaviours on surfaces. Chapter II gives an overview of the experimental techniques and introduces basic concepts of theoretical calculation. Chapter III investigates the effect of experimental parameters, e.g. surface coverage, annealing temperature and substrate temperature on molecular diffusion, molecular orientation and ordering of the adlayer structures. LT-STM examination of the contrast variations of adenine chains and isolated adsorbate as a function of the tip-sample bias voltage is also presented with the aim to understand the tunnelling mechanism. Chapter IV shows RAIR spectra studies of the evolution of phenylglycine molecular orientation as a function of surface coverage at room temperature. The adsorption geometry and binding nature of phenylglycine is discussed. Chapter V concerns with the adsorption behaviours of phenylglycine and adenine on Cu(110) surface pre-covered with oxygen. Chapter VI summarises the conclusions and describes the outlook of some future work.