X-ray crystallography elastic X-ray scattering include powder diffraction, Small-Angle X-ray Scattering (SAXS) and several types of X-ray fiber diffraction, which was used by Rosalind Franklin in determining the double-helix structure of DNA. In general, single-crystal X-ray diffraction offers more structural information than these other techniques; however, it requires a sufficiently large and regular crystal, which is not always available. These scattering methods generally use "monochromatic" X-rays, which are restricted to a single wavelength with minor deviations. A broad spectrum of X-rays (that is, a blend of X-rays with different wavelengths) can also be used to carry out X-ray diffraction, a technique known
Rudolf Signer from the Thymus of calves, of which he took 15 grams of extraordinarily pure DNA to London. In England he gave it to various scientists, among them Maurice Wilkins, in order to promote research in the field. The analysis of X ray images of these DNA samples in Wilkins' laboratory allowed James Watson and Francis Crick to discover the double-helix structure of DNA. Rests of the DNA which Signer brought to England, survive today in the collection of King's College, London. Over 250 of Signer's scientific writings were published during his lifetime. The Lavoisier Medal was awarded to him for