“…The MS technique is applied to different types of compounds by the use of an appropriate ionization source. For example, electron impact (EI) ionization, chemical ionization (CI), matrix-assisted laser desorption/ionization (MALDI), and electrospray ionization (ESI) are widely used in current organic or biological molecule identification, while inductively coupled plasma (ICP) and glow discharge (GD) techniques are suitable for element determination. − For the analysis of organometallic species, EI, ESI, and MALDI sources are commonly used. − The analyte must be vaporized for EI, dissolved in a proper solution for ESI, or cocrystallized with a matrix for MALDI, which may induce decomposition of analyte and increase the chance of contamination. Indeed, by focusing a sufficiently bright laser beam onto a solid target, with laser irradiance of 10 7 W/cm 2 , some organic molecules can be directly desorbed and ionized without matrix assistance.…”