Selective laser ablation/ionization for ion trap mass spectrometry: Resonant laser ablation

Laser ablation provides a clean, broadly applicable ionization source for ion trap mass spectrometry. However, the ion storage capacity of an ion trap mass spectrometer requires a degree of selectivity in either the ion generation or ion storage process to allow effective interrogation of minority components. This can be accomplished by low-intensity irradiation of the sample with laser pulses tuned to a one- or two-photon resonant transition in the analyte of interest. Resonant laser ablation is a multistep process involving evaporation and subsequent ionization of a solid sample component of interest. The leading edge of a tunable laser pulse vaporizes near-surface material, which forms a plume directly above the sample. The trailing edge of the pulse preferentially excites, and subsequently ionizes, the component that is in resonance with the incident photons. In this manuscript, we report on the use of resonant laser ablation with an ion trap mass spectrometer for high sensitivity, high selectivity generation of analyte ions from a solid sample.