The effects of primary ion energy on the extent of fragmentation in desorption ionization mass spectrometry

Improving fast atom bombardment mass spectra: The influence of some controllable parameters on spectral quality

“…These latter reactions are all examples of beam-induced chemical damage, that is, damage resulting from intermolecular interactions with the products of thermal damage (fragments or electrons). In this context, the term "damage" is applied on a molecular scale, rather than with the macroscopic connotation of damage at or near the sample surface, as defined in dry SIMS studies.Important parameters known to affect the extent of beam-induced damage and the abundance of molecular (or quasi-molecular) ions in FAB spectra include the primary beam flux [9-11] and energy [12,13], and the matrix composition [3,[14][15][16][17][18]. Adventitious photons from the FAB gun may also be involved [9].…”

“…Important parameters known to affect the extent of beam-induced damage and the abundance of molecular (or quasi-molecular) ions in FAB spectra include the primary beam flux [9][10][11] and energy [12,13], and the matrix composition [3,[14][15][16][17][18]. Adventitious photons from the FAB gun may also be involved [9].…”

“…However, Alexander and Hogg [19] and Ligon and Dorn [20] showed that multiply charged ions formed in the discharge can acquire up to 5 times the energy corresponding to the anode potential. Although the role of these high-energy ions (comprising 15% of the total primary beam) in the sampling process has not been reported, it may be significant; ions partially or totally neutralized following acceleration [20] can promote high-energy processes distinct from those expected at the nominal primary atom energy [12,13]. Because of these uncertainties, part of this study involves a modest effort to assess semiquantitatively the operational characteristics of our xenon atom gun.…”

Elemental and molecular imaging of human hair using secondary ion mass spectrometry

“…Alternatively, isotopic tagging of the silicone compound could be used to distinguish it from preexisting environmental contamination. Because secondary ion yields for organic compounds increase with the increasing mass of the primary ion beam (Winger et al 1988), we would predict that the Oprimary ion beam would not be as efficient in desorbing organic molecules as the more commonly used Ar + or Ga + ion beams. In an effort to increase the yield of molecular ions from hair surfaces, we have investigated the use of the negatively charged polyatomic primary ion beam, NO 2 -.…”

SIMS analysis: Development and evaluation 1994 summary report

“…The basalt and quartz chips, and the ferrous and ferric oxide powders were exposed to TBP in three different ways: 1) known quantities of aqueous TBP solutions were spiked onto the mineral surfaces, and allowed to dry prior to admitting the samples into the instrument; 2) the mineral samples were immersed in aqueous, and CH2C12 solutions of TBP for typically 1 -2 hours, removed, and allowed to dry; 3) samples were exposed to TBP in the atmosphere, by holding a basalt sample over an open bottle of TBP for 15 to 60 seconds. The concentrations of the TBP/H,O and TBP/CH,CI, solutions were 800 and 1000 ppm, respectively.…”