1. Lecture 5: Microscopy PHYS 430/603 material Laszlo Takacs UMBC Department of Physics

2. Light microscopy The principle and a commercial scope Useful sites: http://www.microscopyu.com/articles/optics/components.html http://em-outreach.ucsd.edu/web-course/toccontents.html

3. Optical microscope (OM) and transmission electron microscope (TEM)

4. TEM modes: Composite image, bright field image, dark field image, selected area diffraction Transmitted and diffracted beamsDiffraction patternFirst image Bright fieldBright field, transmitted electrons only Dark fieldSelected area diffraction pattern

5. Comparing imaging and diffraction in a TEM.

6. Electron diffraction from a monocrystalpolycrystalglass

7. How do scanning microscopies work? 02122111 19721870 28612981 08818701 19796011 17887110 29886121 18929711 08711831 21102101 Image = table of numbers Measurement generates a value for every location: Reflectivity of light (scanner) Ejected electrons (SEM) Current between tip and surface (STM) Force between tip and surface (AFM) Any quantity of interest that can produce useful contrast Interpret numbers as intensities for display or printer. Digital image processing.

8. How do scanning microscopies work? 02122111 19721870 28612981 08818701 19796011 17887110 29886121 18929711 08711831 21102101 Image = table of numbers Measurement generates a value for every location: Reflectivity of light (scanner) Ejected electrons (SEM) Current between tip and surface (STM) Force between tip and surface (AFM) Any quantity of interest Interpret numbers as intensities for display or printer. Digital image processing.

9. The principle of the SEM. There is no image formation in the optical sense. This is classical analog system. Modern SEMs record the measured intensities in a computer memory rather then project them directly on a CRT screen. This way image processing is possible before the final image is created. TV does the same.

10. Measurable effect caused by high-energy electrons

11. Typical morphological contrast by secondary electrons. It only looks like an illuminated landscape. The contrast comes from how many secondary electrons are generated and how efficiently they are collected by the detector. The illumination comes from above, the detector is n the side.

12. Magnifications: very different features are seen on different length scales

13. Depth of field

14. X-ray analysis

15. Images of a Lunar rock: (a) Backscattered electrons (depend on Z) (c) Fe X-rays (d) P X-rays (b) Sketch of phases; m = metal tr = trolite, FeS sc = Fe-Ni phosphide wh = phosphate

16. The principle of STM/AFM