A conversation with John B. Fenn. Interview by M. Samy El-Shall.

Editor's Note: Every year, the Editorial Committee of each Annual Reviews series asks an internationally distinguished researcher to prepare a prefatory article for the volume being planned. It was an easy choice for us to seek a contribution from John B. Fenn (b. 1917), who since 1994 has been a professor of analytical chemistry at Virginia Commonwealth University in Richmond, Virginia. Few people have achieved the originality and the impact that John Fenn has shown in his development of new instruments for chemical analysis. Anyone using supersonic jet expansions or electrospray ionization owes a huge debt to this special individual, who was awarded the Nobel Prize in Chemistry in 2002. A full account of the development of electrospray ionization may be found in Fenn's 2002 article in the Journal of Biomolecular Techniques (see Related Resources at the end of the interview). What follows is a transcript of an interview that Fenn's colleague Professor Samy El-Shall kindly conducted on our behalf. This interview captures the spirit and the imagination of this singular individual. It also shows that the path to discovery is seldom straight and narrow. -Richard N. Zare.