Mauritius Renninger

Mauritius Renninger (born June 8, 1905 , † December 22, 1987 in Marburg ) was a crystallographer and theoretical physicist. After receiving his doctorate in Munich (1932) and then working as an assistant to Paul Peter Ewald , he switched to industry ( IG Farben in Oppau ). In 1946 he returned to the university as an assistant to Carl Hermann . He was then appointed professor at the Philipps University of Marburg . Renninger became known through his work on the detour excitation of the diamond in 1937, also known as the Renninger effect.

Detour excitation

If several reflections meet the Laue condition at the same time during X-ray diffraction , i.e. are located on the Ewald sphere at the same time , this can lead to weak reflections receiving a significant intensity. In the case of diamond, for example, this applies to the reflex with the Laue indices hkl = 222, which, assuming a spherical electron density of the carbon atoms , must have a very weak intensity, but can have significant intensity through detour excitation (up to tenfold amplification). In the experiment, the detour excitation can be determined by the so-called Renninger scan . A reflex is rotated around the vector perpendicular to the diffraction plane hkl (Psi-Scan) so that the Laue condition for the reflex hkl is always fulfilled. Depending on the angle of rotation, further reflexes are then active (or not) and the Renninger effect occurs (or not).

Lightening

Strong x-ray reflections can be weakened by the Renninger effect . This is called brightening because the X-ray intensity was originally measured using X-ray film . At a lower intensity, this film is less blackened ( lightened ).

Web links

• Obituary Mauritius Renninger (PDF file; 438 kB)
• Software for calculating the detour excitation (PDF file; 1.51 MB)
• History of crystallography in Germany ( page 460; PDF file; 933 kB)