Laser desorption mass spectrometry uses a pulsed laser to release material from a condensed-phase sample and generate gas-phase ions for mass analysis. In direct laser desorption, the analyte or substrate absorbs the pulse; in matrix-assisted laser desorption/ionization (MALDI), an excess of a light-absorbing matrix co-crystallized with the analyte mediates energy deposition and ion formation ^[1]. Short irradiation produces a desorption plume containing neutrals, clusters, and ions, and subsequent proton-transfer, cationization, or deprotonation processes determine the detected species. The source is commonly coupled to a time-of-flight analyzer because pulsed ion production provides a natural start time, but the analyzer is not part of the defining ionization principle ^[2]. The method differs from electrospray, which forms ions from charged droplets, and from secondary-ion mass spectrometry, which uses a primary ion beam. Its essential features are pulsed photon irradiation, a localized condensed sample, desorption with ion formation, extraction of the plume ions, and mass-to-charge measurement.