\chapter{Introduction} % TODO: Broad general sweeping statements about thin films So called metallic-black films are the result of deposition of metal elements at a relatively high pressure (of the order of $10^{-2}$ mbar). The films are named due to their high absorbance at visible wavelengths; they appear black to the naked eye. There is a remarkable contrast between such films and films deposited under low pressure (less than $10^{-6}$mbar), which are typically highly reflective and brightly coloured. % First mentions and early research; Pfund This phenomenom has been known since the early 20th century, with the first papers on the subject published by Pfund in the 1930s \cite{pfund1930}, \cite{pfund1933}. Pfund established the conditions for formation of metallic-blacks \cite{pfund1930}, and showed that the transmission spectrum of metallic black films is almost zero in visible wavelengths, but increases to a plateau in the far infrared \cite{pfund1933}. More extensive research on the structural and optical properties of these films by Louis Harris and others during the 1940s and 1950s \cite{harris1948}, \cite{harris1952}, \cite{harris1953}. % Research by Harris concluding ``condensor'' like structure Harris et al. have produced experimental results of the transmission of metallic-black films from visible wavelengths to the far-infrared \cite{}. By modelling the film as a layer of metallic strands, acting as ``condensors'', Harris et al. arrived at an expression for the electron relaxation time of [element]-black \cite{}, leading to a a transmission spectrum in good agreement with experimental results. % Mckenzie Mckenzie has established that the presence of oxygen effects the optical and electrical properties of metallic-blacks \cite{mckenzie2006}. % More recent research More recently, it was shown that Au-black coatings increased the efficiency of thin film solar cells \cite{}. In this study, a simulation approximating an Au-black film as a layer of semi-spherical structures showed plasmonic behaviour which lead to an increase in electric field behind the film. % Artificially ``blackened'' thin films Metallic-black films have proven useful in applications requiring efficient absorption of light, including the. Recently there has been interest in artificial ``blackening'' of metal surfaces in ways which simplify the characterisation of the surfaces for practical applications. Sondergaard et al. have produced metallic-black surfaces capable of suporting surface plasmon modes \cite{sondergaard2012}. These films exhibit similar optical properties to the previously considered ``evaporated'' metallic-black surfaces. % What I will be doing with metallic-black films This project will employ several techniques, including:Total Current Specroscopy; Ellipsometry and Optical Spectroscopy to investigate the difference between metallic films deposited at low pressure, and high pressure (metallic-blacks).