Stanzel, J., Weigand, W., Kilian, L., Meyerheim, H. L., Kumpf, C., Umbach, E.
Chemisorption of NTCDA on Ag(111): A NIXSW study including non-dipolar and electro-stimulated effects
Surface Science 571, (1-3),pp L311-L318 (2004)
The adsorption of one monolayer of 1,4,5,8-naphthalene-tetracarboxylicacid-dianhydride (NTCDA) on the Ag(1 1 1)-surface was studied using the normal incidence X-ray standing waves (XSW) technique. Results regarding two key-issues are presented: Most prominent, the precise adsorbate-substrate bonding distance could be evaluated to 3.02 ± 0.02 Angstrom capital
AA, ring (for the "relaxed monolayer" structure). This value is significantly smaller than a van der Waals bonding distance and clearly indicates the chemisorptive bonding character. Concordant results were obtained from both O 1s photo- and O KLL Auger electron emission. This was enabled by the development of a data analysis procedure -the second issue addressed- which takes into account non-dipolar contributions to the photoemission as well as electron-stimulated Auger excitations. The latter effect adds a fraction to the total Auger yield being as high as 50
AA, ring (for the "relaxed monolayer" structure). This value is significantly smaller than a van der Waals bonding distance and clearly indicates the chemisorptive bonding character. Concordant results were obtained from both O 1s photo- and O KLL Auger electron emission. This was enabled by the development of a data analysis procedure -the second issue addressed- which takes into account non-dipolar contributions to the photoemission as well as electron-stimulated Auger excitations. The latter effect adds a fraction to the total Auger yield being as high as 50