Development of laser-ion beam photodissociation methods. Progress report, December 1991--November 1994

Abstract

This project emphasizes the development of laser mass spectrometry methods for fundamental and applied studies of gas-phase processes. The current studies are focussed on the photochemistry and photophysics of peptides and other biological molecules. Matrix-assisted laser desorption ionization (MALDI) is used to produce ions that are subsequently subjected to photoexcitation and dissociation. MALDI is still very much in the developmental stages, thus a significant portion of this research focusses on fundamental studies of the MALDI ion formation/energy transfer process. The authors view is that excited state H+-transfer reactions play an important role in MALDI, consequently a significant portion of their research activities are focussed on such studies. Fundamental studies of the role of the matrix in MALDI are an integral part of this project. A new MALDI experiment, MALDI of aerosol particles generated from solutions, has been demonstrated and new developmental research in this area is planned. The authors are also actively pursuing a research program on gas-phase H+-transfer processes that mimic the MALDI process. In addition, they are developing photodissociation experiments, based on tandem time-of-flight mass spectrometers, for structural characterization of complex organic molecules. The photodissociation studies use MALDI as the ionization method. These research areas involve the development of new instrumentation, new instrument methodologies, and data processing.