Reflection electron energy loss spectrum of surface plasmon excitation of Ag: A Monte Carlo study

Ding, Zejun; Li, H. M.; Pu, Qirong; Zhang, Z. M.; Shimizu, Ryuichi

doi:10.1103/physrevb.66.085411

Cited by 68 publications

(24 citation statements)

References 19 publications

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“…We have previously made such comparisons 13,21 for several metals by using the numerically obtained electron-surface inelastic interaction cross sections, Eqn (3); very good agreements were found in each case of primary beam conditions and materials. However, the experimental curves quoted from literature have not shown the full shape of elastic peak so that the exact normalization with the intensity of elastic peak has not been fully guaranteed.…”

Section: Reels Spectramentioning

confidence: 80%

Monte Carlo simulation study of electron interaction with solids and surfaces

Ding

Salma

et al. 2006

Surface & Interface Analysis

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A brief overview is given on several aspects of applications of the Monte Carlo (MC) simulation method to surface-related electron spectroscopy and microscopy. For the MC modeling of electron interaction with solids, the electron inelastic scattering cross section is calculated by the use of bulk dielectric function with optical constants in a dielectric functional approach. This has enabled the systematic reproductions of the experimental energy distributions of backscattered electrons for a number of elemental materials. An improved calculation of backscattering factor for quantitative AES analysis has been performed on the basis of a new definition and by making use of the up-to-date relevant cross sections. The physical reason is given for the backscattering factor that can be less than unity for very low primary energies close to the ionization energy and/or for large incident angles. For the MC modeling of electron interaction with surfaces, the inelastic scattering of electrons moving in a surface region is treated in a self-energy formalism. The model has enabled the evaluation of the surface excitation effect through the calculation of position-dependent electron IMFP. A simulation of REELS spectra for Ag is compared with an experiment; a reasonable agreement found on the surface plasmon peak intensity normalized with elastic peak intensity thus verifies this modeling of electron interaction with surfaces. Finally, the MC simulation code has been extended to deal with complex sample geometries. By using basic building blocks to construct a complex geometry and the ray-tracing technique for correction of electron flight-step-length sampling, the structured and/or inhomogeneous sample can be modeled with reasonable flexibility.

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Section: Reels Spectramentioning

confidence: 80%

Monte Carlo simulation study of electron interaction with solids and surfaces

Ding

Salma

et al. 2006

Surface & Interface Analysis

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“…For noble metals such as silver, however, there are interband transitions that overlap, 30 making surface excitation very complicated. Furthermore, according to the results of Ding and Shimizu,16 there are two surface plasmon peaks at ¾3.7 and ¾7.5 eV. Hence, the /ω s estimation for free-electron metals might not be used directly as an estimation of the effective surface depth for Ag.…”

Section: Effective Surface Depth For Silvermentioning

confidence: 95%

“…Ding and Shimizu 16 have also reported surface excitations occurring in solids and vacuums in their study of the REELS spectrum of surface plasmon excitation of Ag. In their work, the differential inelastic cross-section is obtained from inhomogeneous electron self-energy in the surface region.…”

Section: Introductionmentioning

confidence: 95%

Effective depths for surface excitation derived by reflection electron energy‐loss spectroscopy analysis

Zhang

Iyasu

Shimizu

et al. 2004

Surface & Interface Analysis

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A method of estimation is proposed for determining the effective depth of surface excitation. For this, the effective differential inverse inelastic mean free path (DIIMFP) is presumed to be represented as a linear combination of theoretical DIIMFPs for surface and bulk excitation, which are derived by the use of optical dielectric constants. The effective DIIMFP in the approach is derived by a reflected electron energy-loss spectroscopy analysis based on the extended Landau approach. The present analysis for 1 kV electrons has led to a simple estimation of the effective depth for surface excitations (∼14.5Å for Al and ∼21Å for Ag), agreeing well with an estimation given by u/! s , where u and ! s are the velocity of the primary electrons and the average surface plasmon frequency, respectively.

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“…It should be mentioned that EELS has been applied for decades to detect surface plasmons 1,[7][8][9][10][11][12][13][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][12][13][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).…”

mentioning

confidence: 99%

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

Liu

Zhang

et al. 2014

Nature Phys

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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...

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Reflection electron energy loss spectrum of surface plasmon excitation of Ag: A Monte Carlo study

Cited by 68 publications

References 19 publications

Monte Carlo simulation study of electron interaction with solids and surfaces

Monte Carlo simulation study of electron interaction with solids and surfaces

Effective depths for surface excitation derived by reflection electron energy‐loss spectroscopy analysis

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

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