Applied Physics A, Materials Science & Processing vol:107 issue:1 pages:183-186
We report on confinement of the series of two-dimensional (2D) electron gases provided by image-potential states (ISs) above wire-like Co nanoparticles that are formed at Au(111) step edges upon Co atom deposition. Maps of the local density of states recorded by means of scanning tunneling microscopy reveal the formation of standing wave (SW) patterns at the Co nanowire surface caused by effective scattering at its boundaries. Due to the simple rectangular shape of the wire-like Co nanoparticles, SW patterns, which reflect the eigenfunctions of the particles, are unambiguously resolved. Quantitative comparison to the confinement of Co surface state electrons reveals that the IS electrons follow a similar particle-in-a-box type behavior. These findings open new perspectives for investigation of quantum size effects of 2D electron systems above nanostructured surfaces.