Where X-Rays Come From: Cu Kα Spectrum | Crystallography 2.4

On 8 November 1895 a screen glowed two meters from a shielded discharge tube, and the rays behind it turned out to be just the right size to measure atoms. This episode follows an electron inside an X-ray tube: braking gives a smooth spectrum with a sharp short-wavelength cutoff, and refilling an empty K shell gives the copper Kα and Kβ spikes that Moseley later used to order the elements. A nickel foil, whose absorption edge falls between those two lines, then leaves a single wavelength of 1.54 Å. Chapters 0:00 A glowing screen in Würzburg 1:50 Inside an X-ray tube 2:25 Braking electrons make light 2:58 The shortest wavelength: λmin = hc/eV 4:00 Sharp spikes above 9 kV 4:30 Electron shells and Kα, Kβ 6:03 Moseley's straight line 7:39 Three lines in one beam 8:11 How matter absorbs X-rays 8:48 Nickel's absorption edge 9:18 A nickel foil removes Kβ 10:07 The fluorescence trap with iron 10:29 One wavelength, 1.54 Å 10:53 Three things to take away 11:24 Next: a wave meets a lattice Reference: M. Martínez-Ripoll (with the late F. Hernández Cano), Crystallography-Cristalografia, web course (CSIC, CC BY-NC 4.0, https://www.xtal.iqf.csic.es/Cristalo..., and university crystallography and diffraction lecture notes. Historical sources: Röntgen, Nobel Prize biography: https://www.nobelprize.org/prizes/phy... · Barkla, Nobel lecture (1920): https://www.nobelprize.org/uploads/20... · Barkla, The spectra of the fluorescent Röntgen radiations, Phil. Mag. 22, 396 (1911): https://doi.org/10.1080/1478644090863... · Moseley, The high-frequency spectra of the elements, Phil. Mag. 26, 1024 (1913): https://doi.org/10.1080/1478644130863... Previous episode: 2.3 "Oxide Families". Next episode: 2.5 "The Reciprocal Lattice". Narration: AI voice (ElevenLabs); music: AI-generated (Lyria) and original synthesized tracks.