# ARTHUR LINDO PATTERSON (1902 - 1966). *A Fourier Series Method for the Determination of the Components of Interatomic Distances in Crystals*. (*Phys. Rev.* **1934**, *46*, 372-376.)

Patterson was born in Nelson, New Zealand, and became an American citizen in 1945. In 1923 he received a B.Sc. and in 1924 an M.Sc. at McGill University in Montreal. He then went to work with William H. Bragg, at the Royal Institution, London, from 1924 to 1926. He later held research positions at the Kaiser Wilhelm Institute in Berlin, the Rockefeller Institute in New York, the Johnson Foundation in Philadelphia, MIT, Bryn Mawr College, the Naval Ordnance Laboratory, the Institute for Cancer Research, and the University of Pennsylvania.

During his time in Germany he developed the idea that something could be learned about molecular-structure analysis from Fourier theory. He was so convinced of this that he spent three years doing private research at MIT from 1933 to 1936. In the course of studying the scattering of X-rays by liquids, which can give information about the local atomic environments about the atoms, he noticed that a key mathematical formula could be applied to analyze the diffraction of X-rays by crystals.

Essentially, what Patterson did was to figure out a way to take the reflection intensities F2 and compute from them a plot called a Patterson map in which peaks represent interatomic vectors. Analysis of the locations of the peaks in the Patterson map, combined with information about the space group of the crystal, often enables the crystallographer to deduce where the atoms must reside in the crystal. Patterson's discovery of this method resulted in his famous paper (*A Fourier Series Method for the Determination of the Components of Interatomic Distances in Crystals*) on the interpretation of the "F2 series," so called by him, but generally referred to as the Patterson function.

However, the full implementation of the function had to wait many years for development of practical means of summing the Fourier series in two and three dimensions. At first, this was done with the help of paper methods called summation strips, but its full power wasn't realized until the advent of electronic computers.

Patterson's method has been called "perhaps the most important single development in crystal-structure analysis since the discovery of X-ray diffraction itself."

Anon. "Arthur Lindo Patterson; Crystal Structure Analyst," *Physics Today ***1967** *(Feb.)*, 97-99.

R. E. Marsh and D. P. Shoemaker, "Arthur Lindo Patterson 1902 -1966," *Acta Crystallographica***1967**, *22*, 749-750.