SEARCH

SEARCH BY CITATION

Keywords:

  • Laser-SNMS;
  • photoionization;
  • biomolecules;
  • polyatomic ions

Laser secondary neutral mass spectrometry (Laser-SNMS) has been used to simultaneously ionize sputtered secondary neutrals in a nonselective way. To investigate the sputtering and photoionization processes, we examined the dependence of the Laser-SNMS molecular yield on (i) different primary ion bombardment conditions using mono- and polyatomic ions and (ii) the laser parameters wavelength and laser power density. The Laser-SNMS experiments were carried out using Ga+, Bi1+, Bi3+ and Bi5+ as primary ions and two different excimer laser systems for photoionization working at wavelengths of 157 and 193 nm, respectively, with power densities varying between 4 × 106 and 4 × 108 W/cm2. It was found that Bi3+ as primary ion is most suited to investigate organic surfaces. The highest yields could be obtained using a laser wavelength of 157 nm after ionization. Copyright © 2012 John Wiley & Sons, Ltd.