title: Infrared femtosecond laser preionization in secondary ion mass spectrometry of silver surface.
abstract: An alternative secondary ion mass spectrometry utilizing laser preionization is introduced. The native Ag sample surface is first irradiated with laser pulse (100 fs duration, 10(10)-10(11) W/cm(2) intensity, 1240 nm wavelength) and subsequently bombarded with primary ions (Bi(3)(+), 10 ns duration, 25 keV energy). Multiple correlation patterns are observed in the mass spectra, confirming the mutual laser-secondary ion mass spectrometry (SIMS) interplay in the preionization mechanism. The Ag(+), C(3)H(5)(+), C(3)H(5)O(3)(+), and AgOH(+), C(4)H(5)O(4)(+) are observed with the shallow and steep increasing of intensities at 1.3 × 10(11) W/cm(2) and 1.5 × 10(11) W/cm(2), respectively. Two ionization mechanisms are identified, the ion sputtering regime for intensities of less than 1.4 × 10(11) W/cm(2) and the multiphoton ionization at higher intensities. The Ag saturation intensity obtained from fitting is 2.4 × 10(13) W/cm(2), close to the one reported for postionization. The proposed preionization approach might eliminate the need for high peak power/high intensity laser source and, moreover, the experiment geometry ensures that large areas of the sample are affected by the laser beam.
authors.affiliation: International Laser Centre, Ilkovicova 3, 841 04, Bratislava, Slovakia. lorenc@ilc.sk
authors.forename: Dusan
authors.initials: D
authors.lastname: Lorenc
authors.forename: Eduard
authors.initials: E
authors.lastname: Jane
authors.forename: Monika
authors.initials: M
authors.lastname: Stupavska
authors.forename: Monika
authors.initials: M
authors.lastname: Jerigova
authors.forename: Dusan
authors.initials: D
authors.lastname: Velic