Eu valence in ultra-thin layers of EuF₃ derived from photon energy dependent photoemission and photoabsorption

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• 作者：J. Szade ; W. Burian ; M. Zangr ; o ; F. Bondino ; E. Magnano ; S. Widuch ; Z. Celiń ; ski
• 关键词：Photoemission (total yield) ; Soft X-ray photoelectron spectroscopy ; X-ray photoelectron spectroscopy ; Synchrotron radiation photoelectron spectroscopy ; X-ray absorption spectroscopy ; Metal– ; insulator interfaces ; Europium fluoride
• 刊名：Surface Science
• 出版年：2008
• 出版时间：15 April 2008
• 年：2008
• 卷：602
• 期：8
• 页码：1525-1531
• 全文大小：806 K

文摘

X-ray absorption (XAS) and resonant photoemission (RESPE) have been used to study Eu valence in ultra-thin EuF₃ layers grown by MBE. It was shown that resonant photoemission (RESPE) from EuF₃ ultra-thin layers exhibits different features for photon energies close to the 4d–4f threshold (130–150 eV) and the 3d–4f excitation region (1120–1170 eV). For the low energy resonance a clear effect of resonance induced Eu²⁺ states (final state 4f⁶) has been found whereas no divalent Eu states have been observed when photon energy was tuned to the 3d–4f transition. Our results indicate that Eu valence derived from the XAS and RESPE spectra depends on photon energy and is dominated by the final state effects for the 4d–4f resonance. An explanation is given based on the screening effect and different decay channels of the 4d–4f and 3d–4f resonances.