Surface plasmon excitation of Au and Ag in scanning probe energy loss spectroscopy

Pulisciano, Adriano; Park, S. J.; Palmer, Richard E.

doi:10.1063/1.3006435

Cited by 29 publications

(24 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The energy-loss peak located at about 3.7 eV is associated with the SPR excitation of Ag. Our spectrum is in excellent agreement with those reported by Palmer's group, who also used scanning probe electron spectroscopy to investigate the EELS of Ag surfaces 15,16 . In their experiments, a tip withdrawn a distance from the tunnelling region was invoked as a field-emission electron source when a bias voltage of hundreds of volts was applied.…”

supporting

confidence: 81%

“…5d). However, similar to the results of Palmer's group 16 , an increase of RI has not been observed for 100 nm Ag@HOPG (Fig. 5e).…”

supporting

confidence: 77%

“…In other words, the SPR peak of EELS should thus be significantly enhanced, and its transition probability should be quadratically dependent on the external field, as clearly confirmed by our experimental observations. It is noted that with a similar experimental set-up, Palmer's group observed no enhancement of SPR excitation on the Ag surface 16 , although the strength of the electric field introduced by the tip bias in their experiments was much larger than ours. This might be due to the difference in the samples employed.…”

mentioning

confidence: 60%

“…This suggests that the enhancement of SPR excitation should be attributed to the electric field rather than the tip voltage or the incident electron energy. According to the previous experimental observations of Palmer's group 16 in the energy range of our experiments, the increase of the incident electron energy should actually cause a decrease of the SPR peak intensity, rather than the huge enhancement as observed here. The observation of the nonlinear electron scattering is further illustrated by the dependence of RI on the sample current at three tip-sample distances, which is shown in Fig.…”

mentioning

confidence: 83%

“…For each measured EELS spectrum, background subtraction using a polynomial function 16 was first performed. The spectrum was then normalized by the height of the ES peak for comparison.…”

Section: Methodsmentioning

confidence: 99%

See 4 more Smart Citations

Nonlinear inelastic electron scattering revealed by plasmon-enhanced electron energy-loss spectroscopy

Liu

Zhang

et al. 2014

Nature Phys

View full text Add to dashboard Cite

Electron energy-loss spectroscopy is a powerful tool for identifying the chemical composition of materials [1][2][3][4][5] . It relies mostly on the measurement of inelastic electrons, which carry specific atomic or molecular information. Inelastic electron scattering, however, has a very low intensity, often orders of magnitude weaker than that of elastically scattered electrons. Here, we report the observation of enhanced inelastic electron scattering from silver nanostructures, the intensity of which can reach up to 60% of its elastic counterpart. A home-made scanning probe electron energy-loss spectrometer 6 was used to produce highly localized plasmonic excitations, significantly enhancing the strength of the local electric field of silver nanostructures. The intensity of inelastic electron scattering was found to increase nonlinearly with respect to the electric field generated by the tip-sample bias, providing direct evidence of nonlinear electron scattering processes. Figure 1a gives a schematic drawing of the scanning probe electron energy-loss spectroscopy (SP-EELS) technique used in this study, the details of which can be found elsewhere 6 . Briefly, it consists of a tip-sample system and a toroidal electron energy analyser (TEEA). The experimental arrangement is sketched in Fig. 1b. A tip made from a 0.42 mm tungsten wire by electrochemical etching is approached to a distance of micrometres from the grounded sample surface, which is prepared by evaporating a 30 nm thin film of Ag on freshly cleaved highly ordered pyrolytic graphene (HOPG). Silver structures with dimensions of tens of nanometres are observed on the sample surface, as illustrated in the inset of Fig. 1b. Electrons are field-emitted from the tip when a negative tip voltage V t of hundreds of volts is applied, and surface plasmon resonance (SPR) of the Ag nanostructures is excited by the field-emission electrons under a strong electric field introduced by the tip-sample bias. The backscattered electrons from the sample surface are collected and analysed by the TEEA. In this way the electron energy-loss spectroscopy (EELS) under a certain tip-sample distance and tip voltage can be acquired.It should be mentioned that EELS has been applied for decades to detect surface plasmons 1,7-14 , and in combination with a scanning transmission electron microscope (STEM) it is capable of mapping the spatial variation of SPRs at the nanoscale 11-14 . The energy-loss feature of Ag systems has been studied extensively by EELS, including low-energy backscattering EELS (refs 1,10) and high-energy transmission EELS (refs 11,13,14). A typical EELS spectrum of Ag nanostructures is shown in Fig. 1c, which was obtained at a tip-sample distance of 114 µm with a tip voltage of −246 V and a sample current of 10 pA. The energy-loss peak located at about 3.7 eV is associated with the SPR excitation of Ag. Our spectrum is in excellent agreement with those reported by Palmer's group, who also used scanning probe electron spectroscopy to investigate the EELS of Ag sur...

show abstract

supporting

confidence: 81%

“…5d). However, similar to the results of Palmer's group 16 , an increase of RI has not been observed for 100 nm Ag@HOPG (Fig. 5e).…”

supporting

confidence: 77%

mentioning

confidence: 60%

mentioning

confidence: 83%

“…For each measured EELS spectrum, background subtraction using a polynomial function 16 was first performed. The spectrum was then normalized by the height of the ES peak for comparison.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations