Journal of Electron Spectroscopy and Related Phenomena 129 (2003) 1–8 www.elsevier.com / locate / elspec Energy calibration and intensity normalization in high-resolution NEXAFS spectroscopy 1 * ¨ A. Scholl , Y. Zou, Th. Schmidt, R. Fink , E. Umbach ¨ ¨ ¨ Experimentelle Physik II, Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany Received 16 August 2002; received in revised form 6 January 2003; accepted 10 January 2003 Abstract Using high-brilliance synchrotron radiation and an ultrahigh-resolution monochromator a wealth of new fine structures can be observed in near-edge X-ray absorption spectra. The potential information gain, however, requires an accurate calibration of the energy scale and a perfect intensity normalization in order to avoid erroneous results, e.g., the occurrence of spurious peaks. By means of the most problematic C 1s edge it is shown how large these effects can be and how appropriate energy calibration and intensity normalization can be achieved.  2003 Elsevier Science B.V. All rights reserved. Keywords: NEXAFS; Calibration; Normalization; Carbon edge 1. Introduction significant fine structure in the unoccupied valence states. Both are sensitive to the chemical bonding The near-edge X-ray absorption fine structure and responsible for electron transport [2–5]. Second- (NEXAFS) technique has become a powerful tech- ly, NEXAFS is a local probe that monitors the local nique to analyse interesting new materials, adsor- distribution of valence states at the different core bates, and thin films [1]. This method is particularly holes that can be selected by the energy dependence useful for the investigation of organic substances, for of the absorption cross section [6]. Thirdly, NEX- at least three reasons. First, the excitation of core AFS is ideally suited to investigate the molecular electrons into unoccupied molecular orbitals yields orientation based on the linear NEXAFS dichroism important information on the electronic structure [3,7–9]. A detailed understanding of the rich fine involving chemical shifts of the core levels as well as structure is backed by appropriate calculations [1,10–13]. These advantages of NEXAFS are best illustrated by a very recent example obtained in our group, the observation of detailed fine structure in *Corresponding author. Tel.: 149-931-88-5186; fax: 149-931- highly-ordered thin films of various organic sub- 888-5158. stances which is due to various electronic transitions E-mail address: achim.schoell@physik.uni-wuerzburg.de (A. and their coupling to vibrations [14]. It is empha- ¨ Scholl). 1 sized that such fine structures can only be observed ¨ Present address: Physikalische Chemie II, Universitat Erlangen, Egerlandstrasse 3, D-91058 Erlangen, Germany. by using a high-brilliance beamline with a high 0368-2048 / 03 / $ – see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016 / S0368-2048(03)00016-1