Secondary Ion Mass Spectrometry Bias On Isotope Ratios In .
Secondary Ion Mass Spectrometry Bias on Isotope Ratios inDolomite–Ankerite, Part II: d 13 C Matrix Effects ski (1, 2)*, Kouki Kitajima (1, 2, 3), Reinhard Kozdon (1, 4), Michael J. Spicuzza (1,2),Maciej G. SliwinJohn H. Fournelle (2), Adam Denny (1, 2) and John W. Valley (1, 2, 3)(1)(2)(3)(4)*WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, Madison, WI, 53706, USADepartment of Geoscience, University of Wisconsin-Madison, Madison, WI, 53706, USANASA Astrobiology Institute, Department of Geoscience, University of Wisconsin-Madison, Madison, WI, 53706, USALamont-Doherty Earth Observatory of Columbia University, Palisades, NY, 10964, USACorresponding author. e-mail: msliwinski@wisc.eduThis study is Part II of a series that documents thedevelopment of a suite of calibration reference materials forin situ SIMS analysis of stable isotope ratios in Ca-Mg-Fecarbonates. Part I explored the effects of Fe2 substitutionon SIMS d18O bias measured from the dolomite–ankeritesolid solution series [CaMg(CO3)2–CaFe(CO3)2], whereasthis complementary work explores the compositionaldependence of SIMS d13C bias (calibrated range:Fe# 0.004–0.789, where Fe# molar Fe/(Mg Fe)).Under routine operating conditions for carbonate d13Canalysis at WiscSIMS (CAMECA IMS 1280), the magnitudeof instrumental bias increased exponentially by 2.5–5.5‰(session-specific) with increasing Fe-content in the dolomitestructure, but appeared insensitive to minor Mn substitution[ 2.6 mole % Mn/(Ca Mg Fe Mn)]. The compositionaldependence of bias (i.e., the matrix effect) was expressedusing the Hill equation, yielding calibration residual values 0.3‰ relative to CRM NBS-19 for eleven carbonatereference materials (6-lm-diameter spot size measurements). Based on the spot-to-spot repeatability of a driftmonitor material that ‘bracketed’ each set of ten samplespot analyses, the analytical precision was 0.6–1.2‰ (2s,standard deviations). The analytical uncertainty for individualsample analyses was approximated by combining theprecision and calibration residual values (propagated inquadrature), suggesting an uncertainty of 1.0–1.5‰ (2s).Keywords: SIMS, carbon isotopes, dolomite, ankerite, matrixeffects.Received 19 Jun 15 – Accepted 27 Sep 15 tude est la deuxi Cette eeme partie d’une s erie quidocumente le d eveloppement d’une suite de mat eriaux la calibration pour l’analyse in situ,de r ef erence destin eapar la m ethode SIMS, des rapports d’isotopes stablesdans les carbonates de Ca-Mg-Fe. La partie I a explor eles effets de la substitution de Fe2 sur le biais dans la partir de la solution solide demesure du d18O au SIMS ala s erie dolomite-ank erite [CaMg(CO3)2-CaFe(CO3)2],alors que ce travail compl ementaire explore la d epen la composition du biais dans la mesure du d13Cdance a 0.789, avec Fe#au SIMS (plage calibr ee : Fe# 0.004 a Fe/ (Mg Fe) molaire). Dans des conditions de fonctionnement de routine pour l’analyse du d13C descarbonates avec le WiscSIMS (CAMECA IMS 1280),l’importance du biais instrumental a augment e de facßon chaque sesexponentielle de 2,5–5,5‰ (sp ecifique asion) avec l’accroissement du contenu en Fe dans la lastructure de la dolomite, mais a sembl e insensible asubstitution mineure du Mn [ 2,6% molaire, Mn/ la composition du(Ca Mg Fe Mn)]. La d ependance abiais (i.e., l’effet de matrice) a e t e exprim e en utilisantl’ equation de Hill, donnant des valeurs r esiduelles decalibration 0,3‰ par rapport au CRM NBS-19 pourdouze mat eriaux carbonat es de r ef erence (avec unetaille de spot d’analyse de 6 µm de diam etre). Bas e sur la spot» d’un mat r ep etabilit e «spot aeriau de contr ole dela d erive analys e avant et apr es chaque ensemble de dix chantillons analys t ees, la pr ecision analytique a ee de 0.6–1.2‰ ( ecarts-types de 2s). L’incertitude analytiquepour les analyses d’ echantillons individuels a e t eapproch ee en combinant la pr ecision et les valeursr esiduelles de calibration (propag ee en quadrature), cequi sugg ere une incertitude de 1.0–1.5‰ (2s).Mots-clés : SIMS, isotopes du carbone, dolomite, ank erite,effets de matrice.doi: 10.1111/j.1751-908X.2015.00380.x 2015 The Authors. Geostandards and Geoanalytical Research 2015 International Association of Geoanalysts1
Accurate isotope ratio measurements from sample materials by secondary ion mass spectrometry (SIMS) require theuse of matrix-matched reference materials (RMs) to correct formass fractionation that occurs as follows: (1) during theproduction and acceleration of ions from the sample surface(sputtering), (2) during the transmission of secondary ionsthrough the mass spectrometer and (3) during detection(e.g., Hervig et al. 1992, Eiler et al. 1997, Fitzsimons et al.2000, Valley and Kita 2009, Huberty et al. 2010). Collectively, these instrumental mass fractionation effects can bereferred to as the measurement or instrumental ‘bias’, sensu theInternational Vocabulary of Metrology (VIM 2008). The term‘bias’ denotes here an ‘estimate of a systematic measurementerror’ (2.18, VIM 2008), the effects of which can becompensated for by a correction or calibration. A systematicmeasurement error, the causes of which can be known orunknown, is the ‘component of measurement error that inreplicate measurements remains constant or varies in apredictable manner’ (2.17, VIM 2008).For a given configuration of the ion microprobe, theinfluence of instrumental parameters on mass fractionation (orbias) during an analytical session can be held largely constant(any minor changes in the magnitude of bias are accountedfor by appropriate drift-monitoring materials). For minerals thatexhibit solid solution behaviour, this leaves the component oftotal bias that is a function of chemical composition in need ofcalibrating (i.e., the sample matrix effect). There is at present nocomprehensive theoretical model for accurately predictingsecondary ion yields and thoroughly accounting for the biasimparted to isotope ratios during sputtering. Accurate isotoperatio determinations are thus only possible if a sufficientnumber of well-characterised RMs are employed to empirically characterise, on a session-by-session basis, the bias as afunction of chemical composition.The focus of this study is an empirical characterisation ofSIMS d13C bias for the dolomite–ankerite solid solutionseries [CaMg(CO3)2–CaFe(CO3)2]. A comprehensive suiteof RMs was developed for the purpose of calibration SIMSanalyses across the range Fe# 0.004–0.789 [Fe# molar Fe/(Mg Fe)]. This work is complementary to a recentcontribution ( Sliwi nski et al. 2015a), wherein we reported onthe development of a suite of d18O-calibration RMs andpresented a SIMS d18O bias calibration for carbonates thatfall along this compositional spectrum. The nature of SIMSd13C bias effects in the analysis of carbonate minerals hasbeen investigated previously for various end-member compositions (e.g., Ca, Mg, CaMg (dolomite), Fe, Mn, Zn, Sr, Pb,Ba), but has been investigated only to a limited extent alongthe dolomite–ankerite and siderite–magnesite solid solutions(e.g., Riciputi et al. 1998).2Experimental proceduresOverview of the methodological approachSamples of naturally occurring carbonate minerals withcompositions along the dolomite–ankerite solid solutionseries were assessed to determine the extent to which eachis homogenous in terms of d13C and cation composition(expressed here as the Fe#). Most aspects of the methodologyare as described in the first part of this study (see Sliwi nski et al.2015a). This includes the following: 1) our approach topreparing clean grain separates of each assessed potentialRM, 2) the preparation of grain mounts for SIMS analysis, 3)analysis of the cation chemistry and its variability by EPMAand 4) bulk analysis by conventional phosphoric aciddigestion and gas-source mass spectrometry to determinethe average (bulk) d13C (VPDB) value of each material thatwas accepted for use as a SIMS d13C-calibration RM.Potential reference materials with suitably homogenouscation chemistry were evaluated for carbon isotope homogeneity on the 6-lm scale by SIMS. There are manyconceivable SIMS studies that would/do benefit from thisadmittedly smaller-than-routine spot size ( 10–15 lmdiameter) in the analysis of carbon isotopes in carbonateminerals. An example is the study of chemo-isotopically zonedcarbonate cements in clastic rocks (e.g., Sliwi nski et al. 2015b).It is not uncommon in such studies to observe chemical zoningon the sub-10 micrometre scale. It is then of interest, forexample, for the interpretation of evolving conditions duringsediment diagenesis, to establish whether changes in thechemistry of successive cement zones are associated withchanges in the isotope ratios of carbon and of oxygen (d18O,d13C). We find that a 6-lm-diameter spot size allows foranalysing smaller-than-routine sample domains, all the whileproviding a degree of analytical precision ( 1.0‰, 2s,standard deviations) that allows for meaningful interpretationsof any isotopic variability that is uncovered at such a scale.During assessment, typically twenty grains of eachpotential RM were measured once each to determine theextent of carbon isotope homogeneity; a potential RM passedtesting if the value of 2 standard deviations (2s) of this set ofmeasurements fell below 1.0‰ (for RMs with slight heterogeneity, a 2s value of up to 1.4‰ was acceptable). Theinstrumental configuration and analytical protocol employedat WiscSIMS for small-spot carbonate d13C analyses (6-lmdiameter spot size; see next sub-section) typically yields avariability within 1.0‰ (2s) for measurements of a nominally homogenous material; this is based on considerations ofcounting statistics, the sample-spot-to-spot repeatability ofmeasured d13C values and the overall stability of the 2015 The Authors. Geostandards and Geoanalytical Research 2015 International Association of Geoanalysts
instrument. The WiscSIMS calibration protocol for mineralsthat exhibit solid solution behaviour calls for measuring eachRM four times (four different grains, once each) and using theaverage value to calculate the bias associated with eachcomposition. A practical SIMS d13C-calibration RM for routineuse is thus one for which the value of two standard deviationsof n 4 replicate analyses varies by less than 1.0‰.Analyses of carbon isotope ratios in carbonate minerals areinherently less precise than d18O determinations due to thelower concentration and less efficient ionisation of carbonunder similar primary ion beam conditions.Carbon isotope determinations by SIMSCarbon isotope measurements were performed using aCAMECA IMS 1280 large radius multi-collector SIMS at theWiscSIMS Laboratory (Department of Geoscience, Universityof Wisconsin-Madison). The data set reported here wascollected during multiple analytical sessions; the examplecalibration curve that will be presented and discussed wasconstructed using data from session S13.Instrumental conditions: A 10 kV, 0.6 nA primary beamof 133Cs ions was focused to a 6 lm diameter on thesample surface, resulting in a sputtering depth of 1 lm.Sample surfaces were made conductive by applying a thingold coat (ca. 60 nm), and charge neutralisation was aidedby an electron flood gun. The secondary optics wereconfigured as follows: transfer lens magnification of 200,contrast aperture diameter of 400 lm, field aperture4000 lm 9 4000 lm, entrance slit width of 122 lm,energy slit width of 40 eV and an exit slit width of243 lm, which corresponds to a mass resolving power of 5000 (sufficient to resolve hydride interferences on 13C).Secondary ion signals were detected simultaneously usingaxial electron multipliers for 13C- and 13CH- (axial and H2,respectively), and a Faraday cup (L2) for 12C-. During routinesample analyses, the 13CH- signal serves as a monitor oforganic matter and other contaminants, which can affectvalues of d13C (especially in biocarbonates). A typical countrate for 12C- ions was in the range of 6–13 9 106 cps andvaried with the composition analysed (e.g. 7.5 9 106 cps forcalcite, 6.9 9 106 cps for end-member dolomite and12.7 9 106 cps for high-Fe ankerite (Fe# 0.789); sessionS13 data). The baseline of the Faraday cup (1011 Ω resistor)was calibrated once daily, whereas the gain of the electronmultipliers was systematically checked and the high voltageadjusted, if necessary, during each set of bracketing RManalyses (after the second of four RM measurements). Theduration of a single measurement was 4 min, whichincluded an initial 20 s of pre-sputtering to remove theoverlying gold coat, followed by an automated 60 sroutine that centred the secondary ion beam in the fieldaperture and optimised its transmission into the massspectrometer, and lastly a collection period of secondaryion signals of 160 s (twenty cycles of 8-s integrations).Results and discussionThe suite of SIMS d13C-calibration RMs representing thedolomite–ankerite solid solution series consists of thirteencarbonate materials ranging in composition from endmember dolomite to ankerite with an Fe# of 0.789(Figure 1, Table 1). The range of d13C values representedby the suite, calibrated by phosphoric acid digestion of mgsize samples and gas-source mass spectrometry, extendsfrom -8.36 to 3.19‰ VPDB (Table 2, Appendix A). Analysesby SIMS using a 6-lm-diameter spot size have shown thed13C value of these RMs to be homogenous to within 1.2‰ (2s for n 20, spot-to-spot repeatability; Table 2).This article is accompanied by online supporting information,which includes: (i) complete EPMA and SIMS data sets(Appendices S1 and S2), (ii) a description of how sampleanalyses are corrected for SIMS d13C bias and theassociated propagation of errors (Appendix S3), (iii) additional examples of calibration curves (Appendix S4) and (iv)an assessment of the repeatability of our potential RMassessment process (Appendix S5).Data presentation and a sample calibrationInstrumental mass fractionation (i.e., bias) associated withmeasurements of d13C-calibration RMs is expressed by theformulation:a13 CSIMS ¼1 þ ðd13 Craw 1000Þ1 þ ðd13 CVPDB 1000Þð1Þ(modified after Kita et al. 2009), where ‘d13Craw’ representsthe background and detector dead-time (when electronmultipliers are used) corrected d13C value of a standardmeasured by SIMS; this value is expressed in conventionalper mil notation (‰) and calculated relative to the 13C/12Cratio in Vienna Pee-Dee Belemnite (VPDB; i.e., normalised to13C/12CVPDB 0.0112372; Craig 1957, Allison et al.1995), but it has not been corrected for bias and istherefore not accurate relative to VPDB. The ‘d13CVPDB’ termrepresents the average d13C value of the same RMdetermined by conventional phosphoric acid digestionand gas-source mass spectrometry (McCrea 1950) and isexpressed on the VPDB scale (Table 2, Appendix A).Because values of a13CSIMS are often close to unity, theyare consistently expressed throughout this article usingd-notation in per mil (‰) and referred to as ‘bias’: 2015 The Authors. Geostandards and Geoanalytical Research 2015 International Association of Geoanalysts3
d13 C bias ðRM UW6220Þ 1 þ ðbiasRM 1000Þ¼ 1000 -11 þ ðbiasUW6220 1000ÞCaMgFeFigure 1. Carbonate Ca-Mg-Fe ternary diagramshowing the range of compositions of UW dolomite–ankerite SIMS d 1 3 C-calibration RMs in this study (seeTable 1).bias ¼ 1000 ð a13 CSIMS -1)ð2ÞPlease note that all equations presented here areformulated such that all mathematical operations involvingmultiplication or division are performed on a-terms (e.g.,if two isotope ratio values that are expressed usingd-notation are to be multiplied or divided, they are firstlyconverted to a-values, then multiplied and/or divided, andsubsequently converted back to values in d-notation). Weexplicitly avoid the common approximation, wheredA - dB ffi 1000lnðaA B ÞThe values of bias for each of the d13C-calibration RMs,calculated by Equation (2), are tabulated in Table 3 formultiple analytical sessions spanning a 2-year period.Table 3 includes the averages of the measured d13Cvalues. The entire SIMS data set is provided in Appendix S2.A sample calibration relating the magnitude of SIMSd13C bias to variation in cation chemistry of the dolomite–ankerite solid solution series is shown in Figure 2a (data fromsession S13; Table 3). Note the two different vertical axes;the left-hand axis represents the working calibration curve,where the d13C bias of each RM is normalised to the bias ofthe drift-monitoring material that is systematically measuredthroughout the duration of an analytical session. During theanalysis of samples with compositions that fall along thedolomite–ankerite series, the drift monitor is commonly theend-member dolomite RM (UW6220; Sliwi nski et al.2015a):4ð3ÞThe right-hand axis of Figure 2a represents values ofSIMS d13C bias (‰) that are corrected for instrumental driftbut that are not normalised to the bias of the drift monitormaterial (i.e., values that represent the per mil differencebetween d13Craw and d13CVPDB). The error propagationassociated with Equation (3) is of the same general form asthat described in appendix S5 of Sliwi nski et al. (2015a).Each batch of ten sample measurements is systematicallybracketed by eight analyses of the drift monitor material,several grains of which are embedded into each samplemount (four analyses of UW6220 before, and four moreafter, each group of ten sample measurements). Instrumentaldrift is thus systematically monitored throughout the durationof the analytical session; this allows for assigning to eachsample-spot measurement a value of d13C bias (based onthe Fe# of the analysed spot) that is appropriately scaled tothe instrumental conditions during calibration (seeAppendix S3).The effect of Fe-substitution on SIMS d13C bias indolomite–ankerite and a matrix bias correctionUnder routine operating conditions for carbonate mineral d13C analysis at WiscSIMS, the magnitude of SIMSd13C bias increases exponentially with increasing Fe-content(i.e., Fe#) in the dolomite–ankerite solid solution. For thesample calibration shown in Figure 2a, the difference in biasbetween the end-members of the series amounts to -4‰(session S13 data, Table 3); that is, the bias was smallest forend-member dolomite (-47.53‰) and largest for the mostFe-rich ankerite (-51.75‰ at Fe# 0.789). All SIMS d13Cbias values discussed in this article are negative (whether ornot they are normalised to the bias of the drift monitormaterial); thus, to avoid confusion with regard to terminology,please note the following: as values become more negative,the absolute magnitude of SIMS d13C bias increases; that is,the per mil difference between the ‘raw’ d13C valuesmeasured by SIMS and ‘true’ d13CVPDB values becomeslarger (and vice versa).Considering the calibration data shown in Figure 2a(session S13, Table 3), the magnitude of d13C bias*(RM-UW6220): (i) changes most rapidly (by 2.5‰) inthe narrow compositional range of ‘nonferroan’ dolomite,defined by Fe# between 0.0 and 0.1 (sensu Chang et al.1996), (ii) changes more gradually (by another 0.75‰from 2.50 to 3.25‰) in the equally narrow compositionalrange of ‘ferroan dolomite’ (Fe# between 0.1 and 0.2) and 2015 The Authors. Geostandards and Geoanalytical Research 2015 International Association of Geoanalysts
2015 The Authors. Geostandards and Geoanalytical Research 2015 International Association of Geoanalysts5(S3) 2014 Mar.(S5b) 2014 Dec.(S2) 2012 July(S2) 2012 July(S3) 2014 Mar.(S4) 2014 July(S4) 2014 July(S4) 2014 lUWAnk6ab202220192222182115152220212119No. ofgrains616830572222546615156660636357No . 80%Mg(mol %52.31%51.
rate for 12C-ions was in the range of 6–13 9 106 cps and varied with the composition analysed (e.g. 7.5 9 106 cps for calcite, 6.9 9 106 cps for end-member dolomite and 12.7 9 106 cps for high-Fe ankerite (Fe# 0.789); session S13 data). The baseline of the Faraday cup (1011 Ω resisto
Use of Secondary Ion Mass Spectrometry as a thin film characterization tool October 17, 2019 Jeff Mayer, Ph.D. Eurofins EAG. EAG background . Secondary ion yields can change by 6 orders of magnitude or more! We cannot calculate or predict ion yields (many have tried and failed)
Secondary ion mass spectrometry 2 m 0e m. Br qEr sample. detector. ion source. electrostatic sector analyser. magnetic sector analyser. P r i m a r y b e a m. Secondary beam. r. e. r. m. E. 0. B. 0 100 200 300 400 500 600 1 10 100 1000. Intensity (counts/sec) 10000 Sputter time (sec) Depth profile. 020 40 60 80 100 1 10 100 1000 10000. Counts .
polyatomic ions: a. amm onium ion b. sulfate ion c. sulfite ion d. carbonate ion e. nitrate ion f. permanganate ion g. hypochlorite ion h. phosphate ion i. cyanide ion j. hydroxide ion 9.2 Naming and Writing Formulas for Ionic Compounds A. _ Ionic Compounds 1. What are Binary Ionic Compounds? 2.
Secondary ion mass spectrometry (SIMS) is an analytical technique in which charged particles (secondary ions) emitted from a surface subjected to bombard- ment by energetic (primary) ions are mass analyzed and detected (ref. 1 . Typ- ically, positive ions are accelerated and focused onto a solid target. .
Secondary Ion Mass Spectrometry 2 MT.10 where E is the energy of primary ion, dE/dx the energy loss per unit length perpendicular to the surface. For 1 keV Ar on copper, dE/dx 100 eV/Å and R 10 Å. A common estimate is R 10 Å / 1 keV. An important parameter related to the sputtering process is the atomic sputter yield Y , defined as
ION 7550 / ION 7650 User Guide The ION meter in an Enterprise Energy Management System Chapter 1 - Introduction Page 11 The ION meter in an Enterprise Energy Management System You can use ION 7550 and ION 7650 meters as standalone devices, but their extensive capabilities are full y realized when used with ION software as part of an
Table 3 Additional Ion kits used with the Ion 16S Metagenomics Kit Description Cat. no.[1] Quantity Ion Plus Fragment Library Kit 4471252 1 kit Ion Xpress Barcode Adapters 1-16 Kit[2] 4471250 1 kit Ion PGM Hi‑Q OT2 Kit A27739 1 kit Ion PGM Enrichment Beads 4478525 1 kit Ion PGM Hi‑Q Sequencing Kit (use with Ion PGM .
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a key analytical technique for detecting, identifying, and imaging the distribution of both elements and organic molecules on the surface of materials. TOF-SIMS is the only imaging mass spectrometry technique that provides less than 70 nm spatial resolution.
