Imaging of vapor plumes produced by matrix assisted laser desorption: A plume sharpening effect

The first gated imaging of both light matrix molecule and heavy biomolecule vapor expansion during matrix assisted laser desorption and ionization is reported, revealing a plume sharpening effect. Laser induced fluorescence i maging of dye-tagged DNase I proteins shows that these heavy molecules (30 000 Da) propagate within a very narrow angular distribution compared to tha t of the 3-HPA matrix (139 Da). A special solution of the gas dynamic equat ions is developed to describe the 3D coexpansion of heavy and light plume c omponents.