Jurnal Sains Nuklear Malaysia, 2011, 23(2): 26-45 ISSN: 2232-0946 Correspondence author: zaidi@uthm.edu.my XPS, AES AND LASER RAMAN SPECTROSCOPY: A FINGERPRINT FOR A MATERIALS SURFACE CHARACTERISATION Zaidi Embong* Science and Mathematics Department, Faculty of Science, Art and Heritages University Tun Hussein Onn Malaysia (UTHM), Parit Raja, Batu Pahat, Johor, Malaysia ABSTRACT This review briefly describes some of the techniques available for analysing surfaces and illustrates their usefulness with a few examples such as a metal and alloy. In particular, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and laser Raman spectroscopy are all described as advanced surface analytical techniques. In analysing a surface, AES and XPS would normally be considered first, with AES being applied where high spatial resolution is required and XPS where chemical state information is needed. Laser Raman spectroscopy is useful for determining molecular bonding. A combination of XPS, AES and Laser Raman spectroscopy can give quantitative analysis from the top few atomic layers with a lateral spatial resolution of <10nm. Keywords: AES, XPS, laser Raman microscopy, surface characterisation INTRODUCTION The surface of a metal may differ in properties from the bulk material and these differences may vary from surface free energy to differences in composition due to segregation or contamination. Techniques such as X-ray photoelectron spectroscopy (XPS), also called electron spectroscopy for chemical analysis (ESCA), can be used to quantify the chemical composition of surfaces. In this kind of analysis, a specimen is submitted to an X-ray beam and electrons from the valence layers are ejected giving rise to transitions of electrons from inner layers to occupy the generated vacancies. Peaks of binding energy corresponding to these transitions are detected and quantified, giving a [Watt et al., 2003; Wild, 1995; Nordling et al., 1964; Kratos Analytical, 1985]. Auger Electron Spectroscopy (AES) is a powerful method of analysis of the atomic composition of the surface of the targets from which the Auger electrons issue [Lawrence et al., 1995; Madden, 1981]. It has been extensively used now and a number of instruments for surface and thin film studies. Laser Raman spectroscopy (LRS) can be used to obtain information about the vibrational spectrum of a material. This can lead to a better understanding of the chemical composition of the sample, as in many organic compounds, where different chemical bonds have very characteristic vibrational frequencies [Wild, 1995; Vickerman et al 2009]. It may also be possible to deduce the structure of a material; for example, in molecular systems, the juxtaposition of different chemical species leads to small modifications of the usual vibrational frequencies, so that longer-scale structure may be investigated [Vickerman et al., 2009]. Recently, a characterisation of the material surfaces can be performed using three surface analytical techniques, namely X-Ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and Laser Raman Spectroscopy (LRS). XPS and AES are well established analytical tools which are able to provide information about the chemical state and chemical composition of solid surfaces. LRS, on the