ADVANCES IN X-RAY CRYSTALLOGRAPHY

Marcus J. Winter

Agilent Technologies,

Yarnton, Oxfordshire, U.K.

e-mail: marcus.winter@agilent.com

Agilent Technologies (XRD) – formerly Oxford Diffraction, has made some of the most notable advances in X-ray crystallography over recent years.  These include the adaption of graded focussing / monochromating X-ray mirrors to ‘conventional’ fine focus X-ray sources - to achieve the high brilliance Enhance Ultra (Cu) X-ray source. 

Further advances in X-ray source design are marked by the Mova (Mo) and Nova (Cu) microfocus X-ray sources: whilst operating at low powers (typically 40 – 50 W), these sources achieve X-ray brightnesses considerably higher than is possible using 2 – 3 kW fine focus X-ray tubes, and comparable with rotating anode – type sources. 

In parallel with X-ray source breakthroughs, CCD area detector technology has been considerably improved: for instance with the Eos S2 (Smart Sensitivity) and Atlas S2 CCD detectors.  The Eos is the highest sensitivity CCD detector which is commercially available – with a gain of 400 electrons per Mo photon, rapid read-out and 18-bit dynamic range. The much superior dark current (background) and read-out noise characteristics of CCD detectors mean that they considerably outperform the integrating CMOS detector technology.

The benefits of these developments in X-ray source and detector technologies and in the CrysAlis^Pro data-collection and data-analysis software suite will be illustrated through examples from a number of applications.

As a further valuable assistance to the crystallographer, the PX Scanner has been established: this is for the evaluation of the X-ray diffraction properties of crystals directly in situ in crystallisation plates: whilst the (putative) crystals are still growing in their mother liquor.  Some applications of the PX Scanner system will be summarised.