Electron‐Impact (EI) Secondary Neutral Mass Spectrometry (SNMS)

Abstract

IntroductionSince the early days of sputtering it has been known that, for most cases, the fl ux of particles ejected from a solid under ion bombardment consists predominantly of sputtered neutral s ( SN )s [1] . Thus, in order to enhance sensitivity the pioneers of surface investigation by mass spectrometry applied the process of postionization [2] . Very shortly afterwards, however, due to the rather limited postionization effi ciency when using electron beam methods, and also because of diffi culties with parasitic ion and residual gas suppression, the direct detection of secondary ions provided an advantage over using the neutral component of the sputtered particle fl ux. As a consequence, sophisticated SIMS instruments were developed with, prior to SNMS, SIMS being introduced into the fi eld of surfaceand thin -fi lm analysis.In contrast, a serious limitation of SIMS -the so -called matrix effect -emerged whereby, for a certain concentration of an element X, the secondary ion yield could vary by orders of magnitude as a function of the surface contamination and matrix composition (see e.g., Ref.[3] ). Indeed, in many cases -and especially with unknown or technical samples that had changing matrices -this would hamper quantifi cation, or even make it impossible. Subsequently, during the early 1970s, H. Oechsner [4] developed a strategy to improve quantifi cation by using the effective postionization of the neutral particle fl ux via the electron component of a low -pressure noble gas plasma. In addition to the high postionization effi ciency, this special postionization arrangement provided two further advantages: (i) an almost perfect suppression of the secondary ions; and (ii) the possibility of a lowenergy primary bombardment which featured excellent depth resolution for sputter depth profi ling.In the meantime, electron beam and laser SNMS had also been developed for postionization purposes, and had expanded into the fi eld of applied surface -and thin -fi lm analysis. The latter technique is described fully in Chapter 10 of this

Correlation of Interface Impurities and Chemical Gradients with High Magnetoelectric Coupling Strength in Multiferroic BiFeO3–BaTiO3 Superlattices

“…Using calculated relative postionization probabilities, an estimate for the experimental sensitivity factors would be possible for metal alloys. 25 In addition, SNMS with plasma postionization provides an excellent linearity of elemental concentration on measured total intensity over the full dynamic range of up to 10 6 . 25 Because of the lack of suitable concentration standards for all detected elements, our SNMS results in Figures S6 and S7b have to be considered as qualitative as well.…”

“…Additionally, secondary neutral mass spectrometry (SNMS) was used to confirm the SIMS data. The analysis of oxides by static SIMS 22,23 or dynamic SIMS 24 and electron impact SNMS 25…”

Oscillations and huge preferences of PbTe crystal surface sputtering under Secondary Neutral Mass Spectrometry conditions

“…Application of sputtering in Secondary Neutral Mass Spectrometry (SNMS) is known to be an effective method for composition analysis and depth profiling of multicomponent and doped solids [1][2][3]. Recently we successfully used this method for depth profiling across of Eu-doped PbTe single crystals grown from melt [4].…”

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H2, C2H2, CO, and O2

“…59 The sputtered neutrals can also be postionized with an electron beam, similar to a laser. 60 − 63 We can also intentionally exploit the matrix effect by depositing a thin metal layer, usually Au or Ag. 64 , 65 However, depth profiling combined with metal-assisted SIMS can only be performed while using a nonconventional experimental setup.…”