Multiphoton Mass Spectrometry: Metastables

Multiphoton absorption in molecules is a facile method of producing ions. This technique enables one to use visible or near ultraviolet light for the production of molecular ions. This ionization is shown to proceed with near 100% efficiency in a well localized source, the focus of the laser, and a well defined time, the excitation pulse length of the laser. This makes for an ideal ion source for a mass spectrometer. A time-of-flight configuration will be discussed with a present mass resolution of 3000–4000. This high transmission TOF enables a complete analysis of all ions from a single laser shot, providing suitable electronics is available. This unit can also be used to obtain new information on the behavior of ion decay processes near their energetic thresholds (metastables). The method provides detailed information when the laser wavelength or its intensity is tuned. Comparison to conventional mass spectrometry will be given.