1 Electromagnetic Radiation and X-Rays "It's of no use whatsoever[...] this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there." Heinrich Hertz

2 Spectroscopy and X-Ray Analysis Electromagnetic Radiation  Electromagnetic waves  Calculations involving waves  The electromagnetic spectrum  Light and Optics  Refraction and diffraction X-Rays  Discovery of X-rays  Generation of X-rays  Quantum Numbers  Electron Energy Transitions

3 The Electromagnetic Waves Light waves are self propagating waves that consist of both an electronic and magnetic component. Insert electromagnetic wave image here

4 Formulas for Waves Propagation Speed c = λf c is speed of propagation, (m/s) λ is wavelength, (m) f is frequency (/s, Hz, s -1 ) Period T = 1/f f = 1/T Where: T is the period (s) f is the frequency (Hz) Energy E = hf Where: E is the energy of the photon h is Planck’s constant f is the frequency of the radiation For light c is constant and equal to x 10 8 m/s

5 The Electromagnetic Spectrum Insert electromagnetic spectrum picture here

6 EM Radiation Activity You will each be assigned one of the following types of electromagnetic radiation. Look it up. Report the following information for it:  Wavelength  How it is generated  What it are some common uses Gamma rays, X-rays, Ultraviolet radiation, Light, Infra-red radiation, Microwaves, Radio waves (FM, AM, ELF), Gravity waves.

7 Calculations Calculate the frequency of a red laser pointer light with wavelength 655 nm.

8 Calculations Calculate the wavelength and type of electromagnetic radiation you would expect to produce from a 3 GHz computer.

9 Calculations A common unit in spectroscopy is the “wave number” which is usually defined as the number of waves per cm. How many wave cycles per cm (wave numbers) would you expect to find in radiation produced from a microwave oven operating at a frequency of 2450 MHz?

10 Calculations Copper emits a kα X-ray of 8.04 keV. What would the wavelength be?

11 Light and Optics Electromagnetic radiation  What we see as light is part of the electromagnetic spectrum.  Photon: a unit of electromagnetic energy (light). Photons have no electric charge, they have zero “rest mass” but they do have momentum and energy. 

12 Discovery of X-rays Wilhelm Röntgen Insert Wilhelm Roentgen image here Insert image of the first X-ray here

13 X-ray Tube Insert X-ray tube image here

14 Two methods for generating X-rays Bremsstrahlung / BrakingIonization / Characteristic Insert image

15 X-Ray Analysis Quantum numbers Electron Shells Allowed electron transitions Insert image

16 Quantum Numbers NumberNamePermitted ValuesDefines n Principal(1, 2, 3, …)Electron shell (1=K, 2=L, 3=M …) l Azimuthal0 to n-1Electron cloud shape mlml Magnetic- l to + l Electron shell orientation in a magnetic field msms Spin±½Electron spin direction j = l + m s Inner precession l + m s l ± ½ But j≠ -½ Total angular momentum

17 Principle Quantum Number, n Shell Designation Subshells l Number of states Number of electrons per subshell per shell 1Ks122 2Ls128 p36 3Ms1218 p36 d510 4Ns1232 p36 d510 f714

18 Electron Shells KLILI L II L III MIMI M II M III M IV MVMV n l s +½+½ +½+½ -½-½ +½+½ +½+½ -½-½ +½+½ -½-½ +½+½ j ½½½1½½½ 2½

19 Electron Shells K 1s L I 2s L II 2p -½ L III 2p +½ M I 3s M II 3p -½ M III 3p +½ M IV 3d -½ M V 3d +½

20 Electron Transitions 1. The change in n must be ≥ 1 (Δn ≠ 0) 2. The change in l can only be ±1 3. The change in j can only be ±1 or 0

21 Calculation 1. The change in n must be ≥ 1 (Δn ≠ 0) 2. The change in l can only be ±1 3. The change in j can only be ±1 or 0 Quantum # Δ n l mlml msms j 2p +½ to 1s

22 Example of Electron Transitions Insert image

23 Spectroscopy and X-Ray Analysis Electromagnetic Radiation  Electromagnetic waves  Calculations involving waves  The electromagnetic spectrum  Light and Optics  Refraction and diffraction X-Rays  Discovery of X-rays  Generation of X-rays  Quantum Numbers  Electron Energy Transitions