\begin{abstract}

\section*{Preparation and Characterisation of Nanostructured metal films}


{\bf \emph{Keywords:}} plasmonics, thin films, silver, gold, nanostructures, optical transmission spectroscopy, ellipsometry, total current secondary electron spectroscopy, scanning electron microscopy

Black metal films have been used for a wide range of optical applications for many decades due to their unusual absorbsion properties \cite{pfund1930} \cite{harris1952}. Black metal films have recently been shown to increase the efficiency of thin film solar cells \cite{panjwani2011}. %Advances in nano fabrication technologies have allowed for the creation of ``artificially'' blackened metal surfaces which suppress reflection via surface plasmon scattering of light in nano-grooves \cite{sondergaard2012}. Considering these recent developements, it seems possible that ``traditional'' black metal films may support plasmonic behaviour.

In this project we have produced a range of silver and gold nanostructured films for study using optical and electronic spectroscopic techniques. Scanning electron microscopy images have been used to study the structural differences between black and non-black metal films. A Total Current Spectroscopy experiment has been designed and integrated with sample preparation technology; this allowed us to perform analysis of surfaces in situ. Optical transmission spectroscopy has been used to compare the transmissive behaviour of black and non-black films under visible wavelengths. Variable Angle Spectroscopic Ellipsometry (VASE) has been employed for detailed measurements and modelling of samples.

SEM images confirm that the structure of black metal films is extremely complicated when compared to a non-black film. With Total Current Spectroscopy, we have demonstrated a change in surface potential when a Black Ag film was deposited onto an existing Ag film. Ellipsometric modelling for very thin Ag and Black Ag films shows a notable difference in optical constants of the two films.




\end{abstract}
