Electronic properties and degradation upon VUV irradiation of sodium chloride on Ag(111) studied by photoelectron spectroscopy
| Autor: | Martin Oehzelt, Ruslan Ovsyannikov, Haibo Wang, Norbert Koch, Patrick Amsalem, Stefanie Winkler |
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| Rok vydání: | 2021 |
| Předmět: |
irradiation damage
Materials science Analytical chemistry Halide work function Island growth medicine.disease_cause law.invention X-ray photoelectron spectroscopy law Electrochemistry Materials Chemistry medicine ddc:530 Work function sodium chloride (NaCl) Electrical and Electronic Engineering Bilayer 530 Physik Condensed Matter Physics Electronic Optical and Magnetic Materials Others ddc:621 photon stimulated desorption Vacuum level Scanning tunneling microscope 621 Angewandte Physik photoemission Ultraviolet |
| Zdroj: | Electronic Structure. 3:034008 |
| ISSN: | 2516-1075 |
| DOI: | 10.1088/2516-1075/ac2464 |
| Popis: | The growth as well as vacuum ultraviolet (VUV) radiation-induced degradation of sodium chloride (NaCl) on Ag(111) is investigated by ultraviolet and x-ray photoelectron spectroscopy. In line with previous scanning tunneling microscopy studies, our results confirm that NaCl grows initially as a bilayer before island growth starts. Simple spectroscopic methods for calibrating the closure of the NaCl bilayer are further presented. In addition, the energy level alignment is studied as a function of NaCl film thickness and VUV-light intensity. When measuring with ultra-low photon flux, a sharp interface dipole lowers the sample work function by 0.65 eV upon adsorption of the first bilayer, which is followed by vacuum level alignment for subsequently deposited layers. In contrast, measurements performed with standard photon fluxes, such as those provided by commercial He discharge lamps, shows ‘downward band-bending’-like characteristics in the NaCl films. Upon extended exposure time to the standard VUV intensity, photoemission measurements further reveal that strong modifications of the electronic properties of the NaCl surface occur. These are likely correlated with halogen emission, eventually resulting in the formation of Na clusters promoting low work function of parts of the sample surface. This study provides general guidelines for obtaining reliable spectroscopic measurements on alkali halide thin films on metals. |
| Databáze: | OpenAIRE |
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