John Fenn was an American chemist known for his pioneering work in mass spectrometry. He was awarded the Nobel Prize in Chemistry in 2002 for developing the technique of electrospray ionization, which allows scientists to analyze large biomolecules like proteins and DNA. This innovation has significantly advanced the fields of biochemistry and molecular biology. Fenn was born on June 15, 1917, in New York City and earned his Ph.D. from Yale University. Throughout his career, he held various academic positions, including at Virginia Commonwealth University. His contributions have had a lasting impact on analytical chemistry and have facilitated numerous scientific discoveries.