Scanning probe energy loss spectroscopy: Angular resolved measurements on silicon and graphite surfaces

Abstract

This version: Publisher final versionURL identifying the publication in the King's Portal: https://kclpure.kcl.ac.uk/portal/en/publications/scanning-probe-energy-loss spectroscopy-angular-resolved-measurements-on-silicon-and-graphite surfaces(a6e6d078-998c-47d4-a21a-80876915b51b).

Scanning probe energy loss spectroscopy below 50nm resolution

“…The energy resolution available from a standard metal tip (replacing the monochromator in EELS) is ϳ0.3 eV, so the technique is best suited to the acquisition of electronic excitation spectra. Recent reports [3][4][5] have focused on the information content of the SPELS spectra, demonstrating plasmon modes and interband excitations akin to conventional EELS. An obvious question now is, "What is the spatial resolution of the technique?"…”

“…The RFA analyzer, chosen because of its high throughput, was mounted parallel to the surface, where the signal levels in SPELS are highest. 3 The energy resolution of the analyzer was ϳ0.1 eV. 9,10 The test sample in the experiments was a Si(111) surface, cleaned in ultrahigh vacuum (UHV) by electron bombardment heating at 1250°C.…”

“…Energy-resolved images of the surface reveal measurable features on the length scale 10-20 nm. This is an innovation in a branch of science (field emission from a metal tip) which dates back [3][4][5]19,20 at least 30 years. The measurements demonstrate that SPELS has the potential to probe the excited states of surface structures, and thus also provide chemical analysis, on the scale of 10-50 nm (and possibly below).…”

New directions in nanoscience: new challenges for surface analysis

“…15,16 Like electron spectroscopies, this is a vacuumbased technique and thus is unable to address samples immersed in solution. Nevertheless, it does have the potential to add spectroscopic (i.e.…”

“…Figure 7 shows the SPELS spectrum from the Si(111)-7 ð 7 surface, to which the bulk and surface silicon plasmon modes (labelled) contribute, and from the graphite surface, where the -band (¾7 eV) and -band (¾27 eV) plasmons are evident. 15 Figure 8 compares the SPELS spectra from a film of gold and silver particles with the spectrum from an evaporated gold film on mica (of the kind imaged in Fig. 3, except that the film is not patterned in this case).…”