John B. Fenn
Born: 15 June 1917, New York, NY, USA
Died: 10 December 2010, Richmond, VA, USA
Affiliation at the time of the award: Virginia Commonwealth University, Richmond, VA, USA
Prize motivation: "for their development of soft desorption ionisation methods for mass spectrometric analyses of biological macromolecules"
Field: physical chemical methodology
Prize share: 1/4
When electrically charged molecules - ions - are accelerated by an electrical field, their speed depends on the ion's charge and weight. By measuring the time it takes for the ions to pass a certain distance, the incidence of different molecules in a test can be determined. It was impossible, however, to use this technique on large molecules, such as proteins, before large ions could be produced in gaseous form. In 1988 John Fenn showed that when a test sample is sprayed with an electrical field, small charged drops are formed, and when the water evaporates, ions in gaseous form remain.