ELECTRON ENERGY LOSS SPECTROSCOPY GZDE ARIBAL 20823751 AYKUT

ELECTRON ENERGY LOSS SPECTROSCOPY GÖZDE ARIBAL 20823751 AYKUT BİLİR 20823842 BORGA DERBENT 20823966

CONTENTS • • • What is the EELS ? The process of historical development How does it work ? Components and properties Why is it used ? Advantages and Disadvantages Compare with EDX Applications Summary References

WHAT IS EELS ? • • • Analytical technique Quantitative analysis Analysis of the inelastic scattering suffered by the transmitted electron beam with measurement of the electron energy distribution Capable of giving structural and chemical information Electron spectrometer

Figure 1 High-resolution electron energy loss spectroscopy (EELS) is a highsensitivity, non-destructive technique for the study of surface and adsorbate vibrations and low-energy electronic excitations.

THE PROCESS OF HISTORICAL DEVELOPMNET • James Hillier • RF Baker in the mid 1940 s • Research 1990 s due to advance in microscope instrumentations and vacuum technology

HOW DOES IT WORK ? • • Can be obtained experimentally In elastic scattering of X-ray photons or optical measurements Change in momentum and direction of propaganation Change in internal degrees of freedom

Figure 2 A typical EELS spectrum from an thin film

COMPONENTS AND PROPERTIES • Magnetic field is between two parallel plates. • Objective aperture • Specimen • Lens • Collector aperture

Figure 3 Photograph of the first electron microanalyzer (Hiller and Baker 1944) •

WHY IS IT USED ? • a) b) c) d) The measurements of Local properties Including specimen thickness Mechanical and electronical Chemical composition

ADVANTAGES • • Higher core-loss signal Higher ultimate spatial resolution Absolute, standardless quantification Structural information available

DISADVANTAGES • • Higher spectral background Very thin specimen needed Possible inaccuracy in crystals More operator intensive

COMPARE WITH EDX Table 1. Comprasion between EELS and EDX.

Table 2. X-ray fluorescence yield for K-, L- and Mshells as a function of atomic number, from Krause (1979)

APPLICATIONS • • • Thickness measurements Pressure measurements Analytical electron microscopy (AEM)

SUMMARY Electron energy-loss spectroscopy (EELS) is an analytical technique that measures the change in kinetic energy of electrons after they have interacted with a specimen.

REFERENCES 1) Journal de Physique IV , Colloque C 7 , supplément au journal de physique III , Volume 3 2) R. F. EGERTON Electron Energy Loss Spectroscopy in The Electron Microscope 3. Edition 3) Yüksek Lisans Tezi NANO ÖLÇEKLİ VANANYUM OKSİT İNCE FİLMLERİN YAPISAL VE ELEKTRİKSEL KARAKTERİZASYONU Ogeday ÇAPAR

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