8 Atomic Physics 8.3 X-ray fluorescence and Moseley's law
Characteristic X-ray lines of different anode materials / Moseley's law
P2541001
Moseley lines; Curve a: transition n2 →n1 (Kα line), Curve b: transition n3 →n1 (Kβ line)
Principle
XR 4.0 X-ray goniometer
Moseley's law describes the relationship between the energy of the Ka lines of characteristic X-ray spec-tra and the atomic number. In this experiment, the characteristic X-ray lines of various different anode materials are determined in order to verify Moseley's law. Tasks 1. Record the X-ray spectra of the three X-ray tubes. 2. Determine the wavelengths and frequencies of the character-istic X-ray lines based on the Bragg angles of the lines. 3. Create the Moseley lines and determine the Rydberg constant and screening constant. What you can learn about ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪
Function and Applications Goniometer with two independent stepper motors for the precise angular positioning of a sample and detector.
Characteristic X-radiation Bohr model energy levels binding energy Moseley's law Rydberg frequency screening constant Bragg scattering
Benefits ▪ Self-calibrating goniometer Plug & measure:
Main articles XR 4.0 expert unit XR 4.0 X-ray goniometer XR 4.0 X-ray Plug-in Cu tube XR 4.0 X-ray Plug-in Mo tube XR 4.0 X-ray Plug-in Fe tube XR 4.0 Software measure X-ray Geiger-Mueller Counter tube, type B XR 4.0 X-ray Lithium fluoride crystal, mounted XR 4.0 X-ray Diaphragm tube d = 2 mm Data cable USB, plug type A/B, 1.8 m
09057-99 09057-10 09057-50 09057-60 09057-70 14414-61 09005-00
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09056-05 09057-02 14608-00
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▪ Automatic identification of the goniometer ▪ Goniometer block with two independent stepper motors for rotating the sample holder and the detector either separately or coupled in a 2:1 ratio ▪ The detector holder with a slit diaphragm holder for absorption foils can be moved in order to change the angular resolution ▪ Includes a light barrier system for limiting the permissible swivelling range and, thereby, for protecting the detectors ▪ Intuitive operation directly at the unit or via a PC Equipment and technical data ▪ Angular increment: 0.1°...10°, Rate: 0.5...100 s/increment ▪ Sample rotation range: 0...360°, Detector rotation range: -10°...+170° ▪ Dimensions (cm): 35 x 30 x 20, Mass (kg): 5 09057-10
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