Laser-Induced Mass Spectrometry With High Lateral Resolution
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
In a conventional Secondary Ion Mass Spectrometry (SIMS) system, ejected secondary particles 2 are ionized for analysis in mass detector 3. In the laser-induced SIMS, two symmetrically incident focussed beams 1a, 1b from a laser with a short pulse length provide additional ionization. A high lateral resolution of the SIMS signal in area 4, which is scanned by continuous primary ion beam 5, is obtained by correlating the output signal of mass detector 3 with the instantaneous position of the primary ion beam. Correlation may be effected by storing the detector signal together with the beam position signal in a computer. A laser with a narrow (e.g., tunable) frequency band can be used if resonant ionization of selected secondary particle species is desired to obtain high sensitivity and selectivity.