What technique did Rosalind Franklin use to study DNA?

Rosalind Franklin used X-ray crystallography to study DNA. More precisely, she used X-ray diffraction methods to record how X-rays scattered from DNA fibers, allowing scientists to infer the molecule’s structure.

At King’s College London, Franklin refined the experimental setup and controlled the humidity around DNA samples, which could exist in different structural forms. Her high-quality diffraction photographs revealed important measurements and patterns consistent with a helical molecule.

The best-known image, Photo 51, was taken in 1952 by Franklin’s graduate student Raymond Gosling under her supervision. Its distinctive X-shaped pattern provided strong evidence for DNA’s helical structure. Franklin’s measurements and analysis became crucial evidence used in the eventual construction of the double-helix model.

X-ray crystallography does not produce a conventional photograph of atoms. Instead, the diffraction pattern is mathematically interpreted to determine how atoms are arranged. Franklin later applied related techniques to the structures of viruses, including tobacco mosaic virus and polio virus.