Louis Harold Gray was a physicist and radiation biologist who specialized in the application of radiation to cancer therapy.
In this letter, Franklin sought his advice regarding the tendency of viruses to break down during long exposures to x-rays,
one of the many challenges in her virus work.
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1957-02-22 (February 22, 1957)
Gray, L. H.
Mount Vernon Hospital
Original Repository: Churchill Archives Centre. The Papers of Rosalind Franklin
Reproduced from the Franklin Collection at the Churchill Archives Centre with the permission of the copyright holder.
I am writing to you at the suggestion of Professor F.S. Dainton. We are studying the structure of crystalline viruses by
means of X-ray diffraction, and are much hampered by the rapid deterioration of the virus crystals in the X-ray beam. We
use 40-50 KV X-rays, and exposures are long. A very rough calculation shows that a crystal of .04 mm^2 cross-section receives
something of the order of 100 Rontgens. per exposure. We should like to be able to make a whole series of measurements on
a single crystal, whereas, at present, deterioration is appreciable, even after a single long exposure. I asked Professor
Dainton whether he thought it would be possible to inhibit chemically the secondary reactions which follow the production
of free radicals by X-rays, and he suggested that I should consult you.
We are already experimenting with the effect of lowering the temperature, and of surrounding the crystal with nitrogen instead
of air. If you have any other suggestion to make, or would spare the time to discuss the problem, I should be glad to come
and see you and should be grateful if you would suggest a convenient time.