Flexi Says: Rosalind Franklin used X-ray diffraction to examine the structure of DNA. Prior to her research in DNA, Franklin used X-ray diffraction to study the structures of protein molecules. In X-ray diffraction, a sample is irradiated with X-rays, which scatter when they interact with electrons in the sample. The scattering patterns can reveal patterns in the arrangement of atoms that make up the sample. Franklin worked for many months to adapt this technique to the study of delicate DNA molecules. In May 1952, Franklin bombarded a strand of DNA with an X-ray beam for 100 hours of exposure under carefully controlled humidity. Diffracted by the electrons in the atoms of the DNA, the rays produced a pattern on a photographic plate. Rosalind then performed mathematical computations to analyze the pattern in the photo. Her photo and computations would help reveal the double helix structure of the DNA molecule.