EMS ACCOUNT - MULTIPHOTON IONIZATION MASS-SPECTROMETRY - PRINCIPLES AND FIELDS OF APPLICATION

Multiphoton ionization exhibits a number of specific features that mak e it a unique ionization technique for analytical and scientific mass spectrometry. Among these is the possibility of selectively ionizing c ertain pre-selected compounds out of complex mixtures with high effici ency while suppressing unwanted substances, a feature that can even be used to distinguish between isomers. Other interesting aspects includ e the ability to control the degree of fragmentation through the laser intensity and to ionize even large molecules intact especially when t he ionization is induced by very short laser pulses. In this account t he basic principles of the technique as well as the experimental requi rements are discussed and some typical applications are demonstrated.