Fast atom bombardment

Fast atom bombardment (FAB) is an ionization technique used in mass spectrometry. The material to be analyzed is mixed with a non-volatile chemical protection environment called a matrix and is bombarded under vacuum with a high energy (4000 to 10,000 electron volts) beam of atoms. The atoms are typically from an inert gas such as argon or xenon. Common matricies include glycerol, thioglycerol, 3-nitrobenzyl alcohol (3-NBA), 18-Crown-6 ether, 2-nitrophenyloctyl ether, sulfolane, diethanolamine, and triethanolamine. This technique is similar to secondary ion mass spectrometry and plasma desorption mass spectrometry.

How it works
FAB is a relatively soft ionization technique and produces primarily intact protonated molecules denoted as [M+H]+ and deprotonated molecules such as [M-H]-. The nature of its ionization products places it close to electrospray and MALDI.