Ion microprobe, SIMS

Fig. 15.15. Schematic of the Cameca IMS 1270, showing the main corqjonents of a high-resolution ion microprobe SIMS instalment. From the magnet radius, the footprint of the instmment can be estimated to about 4 x 3 m. For flexibility, the sample can be bombarded with either Cs ions (by TI) or ions from a duoplasmatron source, which can deliver noble gas or oxygen ions. Reproduced from Ref. [96] with permission. Addision Wesley Longman, 1997.

Scanning Auger Electron Spectroscopy (SAM) and SIMS (in microprobe or microscope modes). SAM is the most widespread technique, but generally is considered to be of lesser sensitivity than SIMS, at least for spatial resolutions (defined by primary beam diameter d) of approximately 0.1 im. However, with a field emission electron source, SAM can achieve sensitivities tanging from 0.3% at. to 3% at. for Pranging from 1000 A to 300 A, respectively, which is competitive with the best ion microprobes. Even with competitive sensitivity, though, SAM can be very problematic for insulators and electron-sensitive materials. 

There are two principal sources of reliable partitioning data for any trace element glassy volcanic rocks and high temperature experiments. For the reasons outlined above, both sources rely on analytical techniques with high spatial resolution. Typically these are microbeam techniques, such as electron-microprobe (EMPA), laser ablation ICP-MS, ion-microprobe secondary ion mass spectrometry (SIMS) or proton-induced X-ray emission (PIXE). 

The importance of surface analysis for evaluating the environmental effects of toxic substances is becoming more apparent as the result of recent work in this field. Chapter 9 describes ESCA, Auger, Ion Microprobe, and SIMS surface analysis techniques for atmospheric particulates. These techniques overcome the obvious limitations of bulk analysis, that is, the wide variability in the physicochemical characteristics of different particles. 

Two different types of SIMS are generally used the Cameca f-series and the SHRIMP (Sensitive High mass Resolution Ion MicroProbe) series (Valley and Graham 1993 Valley et al. 1998 McKibben and Riciputi 1998). Analysis in the... 

Fitzsimons et al. (2000) have reviewed the factors that influence the precision of SIMS stable isotope data. All sample analyses must be calibrated for instrumental mass fractionation using SIMS analyses of a standard material. Under favorable circumstances, precision can reach a few tenths of a per mill. The latest version of ion-microprobe is the Cameca-lMS-1280 type, allowing further reduction in sample and spot size and achieving precise analysis of isotope ratios at the 0. %o level (Page et al. 2007). 

LAMMA 1000 and LIMA. These instruments are designed for tasks in principle comparable to those of dynamic SIMS or imaging ion-microprobes. ... 

In 1967 Liebl reported the development of the first imaging SIMS instrument based on the principle of focused ion beam scanning [24]. This instrument, the ion microprobe mass analyzer, was produced by Applied Research Laboratories (Fig. 4.5). It used an improved hollow cathode duoplasmatron [25] ion source that eliminated filaments used in earlier sources and allowed stable operation with reactive gases. The primary ion beam was mass analyzed for beam purity and focused in a two-lens column to a spot as small as 2 pm. The secondary ions were accelerated from the sample surface into a double focusing mass spectrometer of Mattauch-Herzog geometry. Both positive and negative secondary ions were de-... 

In 1965 Long published a proposed ion microprobe analyzer [27]. Long s student, Drummond, began construction and in 1967 published secondary electron micrographs showing 0.5-pm resolution [28] using a primary beam column. This became the basis for the Associated Electrical Industries (AEI) Ltd. SIMS instrument [29]. This instrument utilized AEI s MS702R spark source mass spectrometer for secondary ion analysis and had a mass resolution of -5000. 

Figure 5 Ion microprobe mass analyzer, first scanning-probe imaging secondary ion mass spectrometer (SIMS). (From Ref. 24.)...

The zircon reference material 91500 discussed before seems to be very suitable for calibrating in situ oxygen isotope analysis. For example, SIMS was employed to study the 8 0 value on the zircon single crystal 91500 . No systematic differences in SIMS 8 0 data were observed between individual fragments of zircon crystal. Peck et alP studied oxygen isotope ratios by ion microprobe analysis for evidence of oxygen isotope variation in continental crust and oceans in 3.3 to 4.4 X 10 year old zircons. In addition, the authors also analyzed rare earth elements (REEs). ... 

Another interesting suite of approaches that undoubtedly wiU be further developed employs SIMS—secondary isotope mass spectrometry (also know as multiple-isotope imaging mass spectrometry (MIMS)). Orphan et al. (2001) applied FISH—SIMS or fluorescent in situ hybridization SIMS to detect isotopicaUy Ught carbon in archaeal ceUs, identifying the Archaea by FISH and using SIMS to quantify the isotopic composition of individual ceUs by ion microprobe. Finzi et al. (2006) applied nanoSIMS to visualize uptake of N2 and C02 by individual ceUs of a... 

Clearly, what is needed is a technique that is readily calibrated and can analyze with spatial resolution of a few microns. Two possibilities, aside from micro-FTIR, appear to exist. Secondary ion mass spectrometry (SIMS) (ion microprobe) is one possibility (Kurosawa et al., 1992, 1993, 1997 Hauri, 2002 Koga et al., 2003), although, like FTIR, it has significant issues with the matrix dependence of the correction factors required. Another possibility that merits further... 

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