Mass spectrometry secondary neutral

Principles and Characteristics The twin techniques of secondary neutral mass spectrometry (or sputtered neutral mass spectrometry, SNMS) and SIMS, which share bombardment of the sample surface with a focused primary ion beam (Ar+, Cs+, Ga+, O2) of sufficiently high ion energy (some keV), are among the most powerful surface analytical techniques for compositional characterisation of surfaces. As in SIMS, in SNMS the implanted primary ions penetrate into the solid surface to different depths (1-10 nm) and transfer their kinetic energy as a function of the sample material, primary ion energy and mass. Whereas SIMS detects the directly emitted secondary ions, in SNMS the secondary sputtered ions are suppressed by a 

Post-ionisation schemes for the detection of sputtered neutral species in SNMS utilise either electron impact ionisation (e-beam SNMS), elecfion gas or plasma ionisation (plasma SNMS) or laser ionisation (L-SNMS). For e-beam SNMS, which is based on the use of a directed flux of essentially mono-energetic electrons towards the sputtered neutrals, high sensitivities have been obtained. Plasma or e-gas SNMS uses a low-pressure plasma (usually inert gas, e.g. Ar) containing ions to sputter the surface and at the same time the e-gas for ionisation of the neutrals. Although e-beam and plasma SNMS suffer from a low ionisation probability, they provide a well-established quantification scheme. 

Surface Analytical Techniques for Polymer/Additive Formulations 

Detection Secondary ions Post-ionisation of neutrals  

Suitable materials All (vacuum compatible) All (vacuum compatible) 

---

Sputtered Neutrals Mass Spectrometry Secondary Neutrals Mass Spectrometry Direct Bombardment Electron Gas SNMS... 

Electron-impact (El) Secondary Neutral Mass Spectrometry (SNMS)... 

Jones, F.R., Interfacial aspects of glass fibre reinforced plastics. In Jones, F.R. (Ed.), Interfacial Phenomena in Composite Materials. Butterworths, London, 1989, pp. 25-32. Chaudhury, M.K., Gentle, T.M. and Plueddemann, E., Adhesion mechanism of poly(vinyl chloride) to silane primed metal surfaces. J. Adhes. Sci. Technol, 1(1), 29-38 (1987). Gellman, A.J., Naasz, B.M., Schmidt, R.G., Chaudhury, M.K, and Gentle, T.M., Secondary neutral mass spectrometry studies of germanium-silane coupling agent-polymer interphases. J. Adhes. Sci. Technol., 4(7), 597-601 (1990). 

SNMS Sputtered and/or secondary neutral mass spectrometry... 

H. Oechsner. Secondary Neutral Mass Spectrometry (SNMS) Recent Methodical Progress and Applications to Fundamental Studies in Particle/Surface Interaction. Int. J. Mass Spectrom. Ion Proc., 143(1995) 271-282. 

Goschnick, J., J. Schuricht, and H. J. Ache, Calibration of Depth Profiles of Microparticles Measured with Plasma-Based Secondary Neutral Mass Spectrometry, Fresenius J. Anal. Chem.,... 

Resonant and non-resonant laser post-ionization of sputtered uranium atoms using SIRIS (sputtered initited resonance ionization spectroscopy) and SNMS (secondary neutral mass spectrometry) in one instrument for the characterization of sub-pm sized single microparticles was suggested by Erdmann et al.94 Resonant ionization mass spectrometry allows a selective and sensitive isotope analysis without isobaric interferences as demonstrated for the ultratrace analysis of plutonium from bulk samples.94 Unfortunately, no instrumental equipment combining both techniques is commercially available. 

Fig. 1.8 Possibilities for spectroscopic research in catalysis (for abbreviations, see Fig. 1.7). AFM Atomic force microscopy ESR Electron spin resonance RBS Rutherford backscattering SNMS secondary neutral mass spectrometry.

Secondary ion mass spectrometry (SIMS) Secondary neutral mass spectrometry (SNMS) Ion-scattering spectroscopy (ISS)... 

The closely allied topics of secondary neutral mass spectrometry (SNMS), fast atom bombardment (FAB), and laser ablation SIMS are important, but are beyond the scope of this chapter. SNMS is a technique in which neutral atoms or molecules, sputtered by an ion beam, are ionized in an effort to improve sensitivity and to decouple ion formation from matrix chemical properties, making quantification easier. This ionization is commonly effected by electron beams or lasers. FAB uses a neutral atom beam to create ions on the surface. It is often useful for insulator analysis. Laser ablation creates ions in either resonant or nonresonant modes and can be quite sensitive and complex. 

---