Spatial and temporal imaging of gas phase protein and DNA produced by matrix-assisted laser desorption

The sensitivity of a transient imaging technique based on laser-excited fluorescence is shown to be within the levels required for studying matrix-assisted laser-desorption (MALD) of large biomolecules. Results show that film morphology, particularly film thickness, has a major influence on plume dynamics. Fluorescent labeling of protein and of DNA is used to allow imaging in UV-MALD-generated plumes. Evidence that intact molecules are monitored is provided. Dye molecules, proteins and DNAs were found to behave very differently in the vaporization process. The spatial and temporal distributions are important for the design of secondary ionization schemes to enhance ion yields, for the optimization of ion collection, and for maximizing resolution in time-of-flight mass spectrometers.