Linus Pauling's contribution to DNA research was the triple-helix DNA model. This model, which was published in 1953, was incorrect, but it did lay the foundation for James Watson and Francis Crick's correct model of DNA as a double helix.
Pauling's model is incorrect because it shows the helical core being formed by phosphates. This is impossible under normal cellular conditions since phosphates, which are negatively charged, would repel each other when forced together. Pauling's misconception is attributed to his lack of access to X-ray diffraction pictures of pure DNA, which were obtained by Rosalind Franklin and Raymond Gosling in 1952.