Today in Science History – January 13 – Paul Niggli and X-Ray Crystallography

January 13 marks the passing of Paul Niggli. Niggli was a Swiss mineralogist who was a pioneer of x-ray crystallography.

Niggli developed the mathematical system of space groups that defined 230 different 3-D atom arrangements based on x-ray diffraction patterns. X-ray crystallography works by shining x-ray radiation through a crystal structure. The x-ray waves interact with the gaps between the individual atoms and create distinct interference patterns. This pattern can give information on the position of the atoms in a crystal, the width of atomic bonds between them, and even the size of the atoms themselves. All that is really needed is a pure sample that can be crystallized.

Early crystallography calculations were done manually. Niggli’s arrangement models made identifying structures in molecules a lot easier and faster.

Notable Science History Events for January 13

1960 – Eric Betzig was born.

Betzig is an American physicist who developed fluorescence microscopy. This microscopy method involves exciting chromophores in the observed sample so they fluoresce at a longer wavelength. The incident light is filtered out. Optical microscope resolutions are limited by the wavelength of visible light. Since the fluoresced light has a longer wavelength, the image resolution is higher. Betzig shares the 2014 Nobel Prize in Chemistry with Stefan Hell and William E. Moerner for their discovery of this technique.

1953 – Paul Niggli died.

1935 – Paul Ulrich Villard died.

Villard was a French physicist and chemist who discovered gamma-ray radiation. He was investigating radioactive emissions from radium salts and found two types of rays could still be detected after blocking the source with lead. One type was similar to Rutherford’s beta rays because they were deflected by magnetic fields. The third type proved to be a very penetrating form of radiation not previously detected. Villard did not name his discovery, but since alpha and beta radiation had been discovered, Ernest Rutherford offered up the name gamma radiation since gamma was the next letter of the Greek alphabet.

Villard developed the ionization chamber method to measure radiation exposure. Prior to this technique, experimenters would hold their hands in front of unexposed photographic plates. Once they exposed their hands and the plate, they developed the image. The amount of exposure could be determined by the quality of the image of the hand.

He began his career studying high-pressure gases. Under high pressures, inert gases can react with water ice crystals to form hydrates. Villard is credited with the discovery of the noble gas crystal compound argon hydrate.

1927 – Sydney Brenner was born.

Brenner is a South African biologist who shares the 2002 Nobel Prize in Medicine with H. Robert Horvitz and John Sulston for their discoveries of how genes regulate organ development and cell death. His research centered on the use of the nematode Caenorhabditis elegans and the identification of which genes control programmed cell death.

1900 – Peter Waage died.

Waage was a Norwegian chemist who, together with his brother-in-law, Cato Guldberg, discovered the Law of Mass Action. This law relates the rate of a chemical reaction is proportional to the amount of active mass, or concentration, of the reactants. This law became the basis for determining rate constants of chemical reactions.

1864 – Wilhelm Wien was born.

Wien was a German physicist who was awarded the 1911 Nobel Prize in Physics for his laws involving the radiation of heat.He determined a blackbody curve at any temperature is determined from the blackbody curve at any other temperature by displacing the wavelength of the emission energy. This is known as Wien’s displacement law.

He determined a blackbody curve at any temperature is determined from the blackbody curve at any other temperature by displacing the wavelength of the emission energy. The peak of this curve is inversely proportional to the absolute temperature of the radiating body. This is known as Wien’s displacement law.