An overview of ultra short wavelengths inmacromolecular crystallography

My abstract for this talk published by the ACA in its Abstracts book was:-

When ESRP released its X-ray undulators specifications in the1980s the
intensities were unprecedented. A report was prepared for ESRP, at CERN,
based on detailed analyses in a visit I made to LURE to work with Roger
Fourme, We modelled cryomounting of a protein crystal with a Cu stalk to
carry away heat from the sample absorbed from the X-ray undulator beam &
modelled thermal heating at short wavelengths. The reduced diffraction
efficiency of the sample could be handled by the increased brilliance. The
ESRP was already 5GeV and so also a high photon energy source. Considering
the ratio of the diffraction efficiency and the absorbed photon versus
energy led Uli Arndt to the idea that gains in measurable diffraction data
per protein sample were possible. At the SRS wiggler, with Britt Hedman and
Keith Hodgson, an experimental simulation of the undulator intensity at an
ESRF but with white beam radiation showed that ~20 micron gramicidin
samples gave nice (Laue) diffraction patterns. Next, tests at CHESS on
their multipole wiggler showed readily measurable diffraction from a
protein crystal specifically at 25keV and 38 keV and led to the ideas of
‘ideal data’ free of absorption errors & of using short wavelength
absorption edge resonant scattering, included in the ESRF Foundation Phase
Report. But, since cryodata MX measurement proved very effective at
controlling radiation damage and various phasing methods developed notably
at the Se K edge, the use of high photon energies for MX went 'quiet'. But
high pressure MX at ESRF ID30 reinvigorated the topic as did MX phasing at
the Xe and Ho K edges (ESRF ID15). We also still don't have a dedicated
charge density Beamline, and where 33 keV would help with the ‘ideal data’
required; a proposal to ESRF from ECDM V has been made.