Charge density studies used to reveal the fine details of atomic electron density, bonds and weak interatomic interactions. The use of this to develop new compounds/applications.

  • Cameron, Stanley (PI)

Project: Research project

Project Details

Description

When a fine beam of X-rays is directed at a crystal, the X-rays are reflected only at specific angles. The intensity of the reflected beam at each of these angles vary and the intensity depends on the arrangement of the atoms in the crystal. It is possible to work out the arrangement of all the atoms within a crystal from a consideration of all the intensities of the reflected X-rays. The X-rays are actually reflected by the electrons around each of the atoms. Most of the electrons are held in a tight cloud close to the centre of the atom (the core electrons), but a few electrons, further away from the atom centre interact with the electron clouds of adjacent atoms. This interaction creates the attraction which holds the atoms together in a molecule. The closely-held electrons are those which reflect most efficiently. It is much more difficult to "see" the other electrons which form the bonds between atoms. However, if the crystal is cooled to below -100oC and the X-ray reflection intensities are measured with real care, it is possible to extract some information about the bonding electrons. It has been found that the bonding electrons have little effect on the intensity of the X-rays reflected at high angles. This allows the calculation of the effect the core electrons would have alone. An examination of the very small difference between the electron clouds, calculated from the core electrons alone, and that actually observed then brings out the details of the bonding electrons. ) We are using this technique to examine the bonding electrons in molecules and have recently developed the technique so that we can now "see" the even weaker interactions that occur between molecules in a solid. These weak interactions are of crucial importance for the way solid materials behave and are also vital for the proper functioning of large biological molecules (eg enzymes). We are planning to examine some simple crystalline solids which - systems for the larger molecules and to produce a complete map and full explanation of all the weak interactions in these model solids.

StatusActive
Effective start/end date1/1/11 → …

Funding

  • Natural Sciences and Engineering Research Council of Canada: US$26,297.00

ASJC Scopus Subject Areas

  • Radiation
  • Inorganic Chemistry