This technique involves shining X-rays at a crystal of DNA and then analysing the resulting diffraction pattern. The diffraction pattern can be used to calculate the electron density of the DNA, which can then be used to build a model of the DNA structure.

Model building

Watson and Crick used the information from the X-ray crystallography data to build a model of the DNA structure. They used sticks and balls to represent the atoms in the DNA molecule, and they arranged them in a way that was consistent with the experimental data.

The double helix model of DNA was published in 1953, and it has since become one of the most iconic images in science. The model has been instrumental in understanding how DNA stores and transmits genetic information, and it has laid the foundation for the entire field of molecular biology.