Portrait of a Molecule

The biggest molecule known to man* is much too tiny to be seen, even under a microscope. But X rays and photography can make molecules dimly visible. Dr. Maurice L. Huggins, a chemist at the Eastman Kodak Research Laboratories, has produced this rare phenomenon--a photograph of a molecule (see cut).

The molecule, magnified nearly 100,000,000 times (its actual size: one forty-millionth of an inch), is hexamethylbenzene, an organic compound derived from coal tar. Its design, deduced from its chemical behavior, has long been pictured in chemistry books as follows:

Dr. Huggins' photograph confirmed the chemists' theoretical picture. In his portrait, the twelve dark spots are the carbon atoms (the hydrogen atoms do not show because they are too light in mass to be detected by this method).

The technique for molecular photography was originated by famed British Physicist Sir William Lawrence Bragg (TIME, Oct. 3, 1938), pioneer in the X-ray study of molecular crystals. He found that X rays, when diffracted by crystals, provide clues for calculating the pattern of atoms in a molecule. Using this information, he developed certain films, made of light and dark bands, which, when superimposed on the X-ray picture, make the atomic pattern visible. By enlargement of such a photograph, a molecule can be magnified 250,000,000 times.

Bragg's method required weeks of laborious calculation. Dr. Huggins reported that, by means of a set of standard light-band masks, he can make a portrait of a molecule in half an hour.

* The tobacco mosaic virus, a "giant" protein molecule eleven-millionths of an inch long.

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