Crystallography “In Our Time”

Nov 292012
 

As part of the Bragg Centenary Celebrations, Melvyn Bragg and his guests discussed the history of crystallography, the study of crystals and their structure on “In Our Time” on BBC Radio 4. His guests were Prof. Judith A. K. Howard (University of Durham), Dr. Christopher Hammond (University of Leeds) and Prof. Mike Glazer (University of Oxford).

The program began with the work of Johannes Kepler in the 17th century, and focussed on the work of the father-and-son team the Braggs in 1912.  It also covered aspects of the the work of the German physicist Max von Laue who had proved that X-rays are a form of light waves and that it was possible to scatter these rays using a crystal and some of the most significant scientific findings of the last century – such as revealing the structure of DNA.

The program is available on line from the “In Our Time” website.

Snowflakes at the Oxford Christmas Light Night

Nov 242012
 

Every year, Oxford Inspires organises an evening of social and cultural events in the centre of Oxford following the theme of Christmas Lights.  A lot of the institutions within the city get involved, and this year that included Amber, who was invited to give a presentation at the Snowflake exhibition held at the History of Science Museum.  The event was held on Friday, 23 November and the Museum opened at 6pm with talks from 7pm in the Gallery (that’s the basement to anyone else, so Amber felt at home).   Activities included:

  • Mirror Snowflakes – Create an infinite variety of symmetrical snowflakes with the help of a pair of mirrors.
  • Paper Crystals – Make your own snowflake decorations for Christmas.
  • Dr. Judith V. Field (Birkbeck College, London), “When Stars of Snow Fell on Kepler’s Coat”
  • Dr. Amber L. Thompson (University of Oxford), “Why Is Snow So Beautiful?”

The evening was very well attended with a very mixed audience.

Why is Snow So Beautiful?

Structure of the Month – November 2012

Nov 012012
 

Presented by: Vanessa E. Fairbank & Dr. Amber L. Thompson
Research Leader: Dr. Andrew L. Goodwin
Published: Physical Review B

Cubic Cd(CN)2 shows the strongest known isotropic negative thermal expansion (NTE; volume contraction on heating).  Variable-temperature single-crystal X‑ray diffraction suggests there is temperature-dependent off-centering of Cd2+ ions that has the effect of increasing the cadmium coordination volume at low temperatures, providing an alternate mechanism for NTE in this material. These displacements are evident in the residual electron density and the highly-structured diffuse scattering in the experimental X-ray diffraction patterns.  Using Monte Carlo simulations, we have interpreted these patterns in terms of a basic set of “ice-rules” that establish a mapping between the dynamics of Cd(CN)2and proton ordering in cubic ice VII.

Structure of the Month – November 2012

Structure of the Month – November 2012