Application Of Electron Energy Loss Spectroscopy Research Articles

On the Application of Electron Energy-Loss Spectroscopy for Investigating Nanostructure of Soot from Different Fuels

Soot is characterized by a multiscale structural organization; the only diagnostic tool that can give access to it is the transmission electron microscope (TEM). However, as it is a diffraction-based technique, TEM images only conjugate aromatic systems and, thus, it is particularly useful to combine it with electron energy-loss spectroscopy (EELS), which is able to provide quantitative information about the relative abundance of sp3 and sp2 hybridized carbon. In this paper, a method for the EELS spectrum analysis of carbonaceous materials, recently developed for electron-irradiated graphite and glassy carbon composition analysis, has been applied for the first time on soot samples, in order to test its performance in soot nanostructure study in combination with TEM and high-resolution TEM (HRTEM). Soot samples analyzed were collected in the soot inception region of premixed flames of different hydrocarbon fuels. EELS, in agreement with TEM and HRTEM, showed a quite disordered and heterogeneous structure for young soot, with a relatively low sp2 content and slight presence of fullerene-like structures, more evident in the case of methane soot hinting to the effect of more saturated aliphatic fuels on soot characteristics at soot inception.

Application of Electron Energy-Loss Spectroscopy for Analysis of the Microstructure of Reactor Materials

Application of Electron Energy-Loss Spectroscopy for Analysis of the Microstructure of Reactor Materials

Performance of a Direct Electron Detector for the Application of Electron Energy-Loss Spectroscopy

Performance of a Direct Electron Detector for the Application of Electron Energy-Loss Spectroscopy

Fundamentals of electron energy-loss spectroscopy

Electron energy-loss spectroscopy (EELS) is an analytical technique that is based on inelastic scattering of fast electrons in a thin specimen. In a transmission electron microscope (TEM) it can provide structural and chemical information about a specimen, even down to atomic resolution. This review provides an overview of the physical basis and new developments and applications of EELS in scanning transmission electron microscopy. Recent advances in elemental mapping, spectrum imaging of plasmonic structures and quantitative analysis of atomically resolved elemental maps are highlighted.

Application of EELS in Materials Science

Abstract Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) has become widely used for the analysis of the composition and electronic structure of materials at the nanoscale. This tutorial review provides an overview of the theory and applications of the technique and a few examples are provided to illustrate the type of information available. Some of the recent developments and future prospects of EELS are discussed.

Application of Electron Energy-Loss Spectroscopy (EELS) and Energy-Filtered Transmission Electron Microscopy (EFTEM) to the Study of Mineral Transformation Associated with Microbial Fe-Reduction of Magnetite

AbstractElectron energy-loss spectroscopy (EELS), energy-filtered transmission electron microscopy (EFTEM), and high-resolution transmission electron microscopy (HRTEM) have been applied in mineralogy and materials research to determine the oxidation states of various metals at high spatial resolution. Such information is critical in understanding the kinetics and mechanisms of mineral–microbe interactions. To date, the aforementioned techniques have not been applied widely in the study of such interactions. In the present study, the three techniques above were employed to investigate mineral transformations associated with microbial Fe(III) reduction in magnetite. Shewanella putrefaciens strain CN32, a dissimilatory metal-reducing bacterium, was incubated with magnetite as the sole electron acceptor and lactate as the electron donor for 14 days under anoxic conditions in bicarbonate buffer. The extent of bioreduction was determined by wet chemistry and mineral solids were investigated by HRTEM, EFTEM, and EELS. Magnetite was partially reduced and biogenic siderite formed. The elemental maps of Fe, O, and C and red-green-blue (RGB) composite map for residual magnetite and newly formed siderite were contrasted by the EFTEM technique. The HRTEM revealed nm-sized magnetite crystals coating bacterial cells. The Fe oxidation state in residual magnetite and biogenic siderite was determined using the EELS technique (the integral ratio of L3 to L2). The integral ratio of L3 to L2 for magnetite (6.29) and siderite (2.71) corresponded to 71% of Fe(III) in magnetite, and 24% of Fe(III) in siderite, respectively. A chemical shift (~1.9 eV) in the Fe-L3 edge of magnetite and siderite indicated a difference in the oxidation state of Fe between these two minerals. Furthermore, the EELS images of magnetite (709 eV) and siderite (707 eV) were extracted from the electron energy-loss spectra collected, ranging from 675 to 755 eV, displaying different oxidation states of Fe in the magnetite and siderite phases. The results demonstrate that EELS is a powerful technique for studying the Fe oxidation-state change as a result of microbial interaction with Fe-containing minerals.

재료 분석에서 전자 에너지 손실 스펙트럼 (EELS)의 원리 및 응용 연구

본 고에서는 최근 재료분석에 활발히 응용되고 있는 EELS 분석장비의 원리와 응용 분야 등에 대해 검토하였다. EELS를 이용하여 수행할 수 있는 주요 응용분야로는 원소의 정성 및 정량분석, 원소 및 화학 맴핑, 화학물의 결함구조를 알 수 있는 전자구조(DOS)에 대한 힌트 등이 있으며, 점차 재료의 근본 적인 성질을 추출할 수 강력한 분석기가 되고 있다. 또한 원소를 분석하고 맹핑하는데 걸리는 시간이 수초에서 수분 이하의 시간으로 매우 짧아 전자빔에 의한 재료의 손상을 최소화시킬 수 있는 장점을 갖고 있다. 특히 나노미터 영역의 분말의 경우 원소의 분포가 불균일하고 전자빔에 의하여 쉽게 변형되는 재료 분석에 매우 유용하다. 향후 TEM의 발달과 함께 EELS는 국부적인 영역에서 가장 다양하고 유용한 정보를 추출할 수 있는 분석기로 자리매김할 것으로 기대된다. An electron energy loss spectroscopy (EELS) instrument attached on transmission electron microscopy (TEM) becomes a powerful and analytical tool for extracting the noble information of materials using the enhancement of TEM images, elemental analysis, elemental or chemical mapping images, electron energy loss near edge structure (ELNES), and extended energy-loss fine structure (EXELFS). In this review, the principle and applications of EELS which is widely used in material, life, and electronic sciences were introduced.

Electron energy loss spectroscopy

Electron energy loss spectroscopy (EELS) is able to provide information on elemental concentration, crystal structure, electronic structure, and chemistry of materials at very high spatial resolution [1]. It has been widely applied to and will play a more significant role in the research of advanced materials [2]. This chapter will review the physics, instrumentation, and applications of EELS, organized as follows:

Application of electron energy-loss spectroscopy to the study of solid catalysts

The addition of an electron spectrometer to a transmission electron microscope provides electron energy-loss spectra and energy-filtered images, from which thickness and chemical information can be extracted. This article reviews the techniques and instrumentation required, together with recent applications involving heterogeneous catalysts.

First Applications of Electron Energy-Loss Spectroscopy with High Energy Resolution

ABSTRACTA new transmission electron microscope equipped with a monochromator and a high resolution energy-filter was used for the first time to fully exploit the chemical bonding information contained in the near edge fine structures (ELNES) of electron energy-loss spectra. The instrument is capable of acquiring spectra with an energy resolution in the range of 0.1 eV, thus opening up the way for improved ELNES information. ELNES spectra of TiO2 and CoO have been recorded and are compared with data obtained with a conventional microscope and with x-ray absorption spectroscopy. In case of the L2,3 edges of the transition metals the new instrument revealed previously unobservable fine structure details, but for the O K edges the improved energy resolution does not result in more detailed structural features than observable in common microscopes. Furthermore, the potential of the new microscope to obtain chemical bonding information at the nanometer scale is discussed.

Observation of Surface Blistering by Grazing Incidence Electron Microscopy

We demonstrate grazing incidence electron microscopy (GIEM) for observation of surface blistering introduced by energetic particle bombardment. This method enebles us direct and nondestructive observation and characterization of surface protrusions without any modification of the microscope, when it is used in combination with associated analytical instruments. As an example, the surface blistering of D+-irradiated single crystalline silicon was examined with the aid of the simultaneous application of electron energy-loss spectroscopy (EELS).

The application of electron energy-loss spectroscopy to the analysis of ultrafine aerosol particles

The use of Electron Energy-Loss Spectroscopy in the Scanning Transmission Electron Microscope, for the single particle analysis of ultrafine aerosol particles, has been assessed using an ambient aerosol sample. It has been shown that under what could be considered routine conditions, compositional data are available from particles down to 5 nm in diameter. Estimates of elemental concentrations were shown to be possible down to 1% in some cases for particles of initially unknown composition. Concentrations lower than this were detectable, but not quantifiable. The use of parallel data acquisition led to credible particle analysis times. Although these were still too long for the technique to be useful in routine analysis, it was shown that the technique is highly applicable where compositional information is required on nanometre-sized particles, and time constraints are not critical.

Some problems and solutions in electron energy loss spectroscopy of cryosections

Electron energy loss spectroscopy (EELS) has been a powerful tool for high resolution studies of elemental distribution, as well as electronic structure, in thin samples. Its foundation for biological research has been laid out nearly two decades ago, and in the subsequent years it has been subjected to rigorous, but by no means extensive research. In particular, some problems unique to EELS of biological samples, have not been fully resolved. In this article we present a brief summary of recent methodological developments, related to biological applications of EELS, in our laboratory. The main purpose of this work was to maximize the signal to noise ratio (S/N) for trace elemental analysis at a minimum dose, in order to reduce the electron dose and/or time required for the acquisition of high resolution elemental maps of radiation sensitive biological materials.Based on the simple assumption of Poisson distribution of independently scattered electrons, it had been generally assumed that the optimum specimen thickness, at which the S/N is a maximum, must be the total inelastic mean free path of the beam electron in the sample.

Dynamical scattering and the quantification of electron energy-loss spectra of solids

An important application of electron energy-loss spectroscopy (EELS) carried out in the electron microscope is to the elemental analysis of microscopic samples which may be as small as 1 nm in linear dimension, i.e. in samples of only 10–20 g. This technique is particularly important for the study of the first row elements of the periodic table which are not easily investigated using the alternative technique of X-ray emission spectroscopy (XRE). Until recently it was thought that uncertainties of some 10% were associated with the detection limit for light elements and for the accuracy with which the concentration of light elements present in the sample could be measured. This limit stems in part from the inaccuracies inherent in the random statistics of the counting process and in part from systematic errors in the calculation of the relevant cross-sections and corrections. However, the improved understanding of the various systematic errors and corrections as well as recent developments in parallel detection means that it should now be possible to carry out chemical analyses with an accuracy of the order of 1% or better. We examine the effect of Bragg scattering, which in electron microscopy must be trated in the dynamical scattering limit, on the accuracy of elemental analysis using EELS. Neglect of this effect may lead to errors of up to 20% in the chemical analysis. The theory of such multiple scattering is outlined and three representative samples are studied: boron nitride, nickel oxide and silicon. These examples permit us to examine the effect of Bragg scattering on estimates of the relative amounts of two elements as well as on estimates of the absolute amounts of a single element.

Application of EELS to the microanalysis of materials

Electron energy loss spectroscopy (EELS) is used in analytical electron microscopy (AEM) because it can provide results on the chemical composition and structure of a small volume of material. The practical application of EELS was demonstrated by the investigation of a refractory hard metal of the type WC-TiC-Co and by the investigation of a BaTiO3 ceramic material. To demonstrate the present status of quantitative analysis by EELS, the spectra of Be2SiO4, TiB2 and BaTiO3 were quantified and the results indicate that quantitative analysis is feasible for major concentrations of light elements and also of heavier elements even in the presence of severe edge overlap.

A TEM fresnel diffraction-based method for characterizing thin grain-boundary and interfacial films

Abstract A method is described by means of which the mean inner potential of glassy grain-boundary or interfacial films of 0·5–1·5 nm in thickness can be measured using transmission electron microscopy. The approach is based on the quantitative assessment of the intensity distribution associated with Fresnel diffraction at the boundary. The measurement of specimen thickness is shown to be the limiting factor in determining the accuracy of the method. Given the simultaneous qualitative application of electron energy-loss spectroscopy, to which the method is ideally complementary in a quantitative sense, the chemistry of a boundary can potentially be derived. The method's usefulness is demonstrated by its application to the characterization of a range of amorphous grain-boundary films in various engineering ceramics.

Electron Energy Loss Spectroscopy in the Study of Surfaces

Inelastic electron scattering provides a powerful technique for the study of the excitations of free atoms, molecules (1, 2), and solids (3). However, its most recent and very significant application has been in surface science, where electron energy loss spectroscopy (EELS) is used extensively to study the excitations of clean surfaces and adsorbates. The first such study was reported by Propst & Piper in 1967 (4), who studied the vibrational spectra of W(lOO) surfaces exposed to various gases with a resolution of 50 meV. The resolution of EELS was significantly improved by Ibach, who in 1970 reported the study of the surface phonons of ZnO with a resolution < 20 meV (5). Due to the efforts of Ibach and others the resolution has bcen improving ever since (currently a 2-3 meV resolution can be achieved), and the scope and applications of EELS have been constantly widening (6). Electron excitation has several features that make it particularly appropriate for surface spectroscopy. First, it covers a very wide spectral range. The Fourier decomposition of the electric field at the surface produced by an electron at a distance d from the surface and moving with velocity v has frequency components up to a cut off frequency we vld. Thus the electron behaves like a source of continuum radiation-a poor man's synchrotron. Therefore, low frequency phonons, high frequency intra-adsorbate vibrational modes, and electronic excitations can be monitored under the same scattering conditions, thus allowing a more complete understanding of the system under study. Second, the strong electron-matter interaction provides both a high surface selectivity and

Application of EELS to the Study of Metal-Hydrogen Systems

The study of metal-hydrogen systems is becoming increasingly important in various energy technologies today, and as a consequence it becomes desirable to be able to characterize the resulting phases as accurately as possible. In this paper we report a preliminary study of metal-hydrogen systems using the technique of electron energy loss spectroscopy (EELS) in an analytical electron microscope (AEM).The study of hydrogen in rare earth metals using EELS was first reported by Colliex et al. in 1976; in that work as well as in this study the characteristic energy loss of plasmon scattering was measured in various metal and hydride phases. Plasmon scattering in general is related to electronic structure of the material and thus the formation of a hydride phase if it affects the electronic structure of the alloy is expected to produce characteristic changes in the energy loss distribution.