ERS201H5 Lecture Notes - Lecture 9: Photographic Film, Diffraction Grating, Electron Microprobe
Document Summary
Discovered in 1895 by wilhelm roentgen: sealed glass tube, hit by electrons produced low-energy radiation, causing fluorescent minerals nearby to glow. 1912: max von laue suggested x-rays might be diffracted by mineral lattice: like diffraction grating o. If so, x-ray wavelength similar to atomic spacing. Bragg and w. l bragg determined crystal structure of halite. Radio waves ( to 300,000 cm) to cosmic rays ( to 3x10-11 cm) X-rays about 100 to 0. 02 ( = 10-8 cm) The electromagnetic spectrum with the visible region expanded. Wavelength ( ) values are expressed in nm (nanometers), where. Outer shell electron falls in to replace lost inner shell electron. Excess energy released as an x-ray: less energy required to hold inner shell electron, energy and wavelength of x-ray are characteristics of particular element and shell difference, k , k , l etc. The numeral indicate specific subshells (1 for s, 2 for p) for the origin of the electron that fills the vacancy.
