Become a Microprobe Power User Part 2: Qualitative & …meteorite.unm.edu/site_media/pdf/Microprobe Poweruser Part 2.pdf · The reason most of us use the probe ... Map, Line, etc

Become a Microprobe Power UserPart 2: Qualitative & Quantitative

AnalysisMike Spilde

Spring IOM SeminarFebruary 5, 2008

Qualitative AnalysisQualitative Analysis• Why use qualitative scans?

–Elemental ID (especially trace element ID)–Locating Background Positions–Identifying peak overlaps

• Setup a Qualitative Scan

ID of Trace Elements:ID of Trace Elements:QualitativeQualitative Jarosite ScanJarosite Scan

<1 wt% P

<0.2 wt% As

Neither the As nor the P will be detected using the EDS

Overlaping Overlaping PeaksPeaksQuestion: Is sulfur present?

Parasitic overlap between Pb M & S K is resolved in WDS Qualitative Scan

Determination of Background PositionsDetermination of Background Positions

Select “Zooming” to zoom in around K & Fe peaks in Channel 2.Then select “Quant. Background”

Question: Will the 2nd order Fe lines interfere with the background positions for K?

Hint: right-click here to “tear off”Spectral Display menu

Upper K background at the default 5 mm offset is too close to 2nd order FeKClick on right background line and drag to the right. Then “Exec” to write to file.

Hi BkgLow BkgPeak

Determination of Background PositionsDetermination of Background Positions

Why it is Important to Check Backgrounds Why it is Important to Check Backgrounds with a Qualitative Scanwith a Qualitative Scan

Low Bkg

2nd order Ca K

80 cts 20 cts

Low background at 5 mm on diopside standard produces 600 cts (10 sec count) background differential. Background measured on enstatite sample yields 200 cts less. Sample has higher counts relative to standard. Result? High totals on sample.

Stored Qualitative ScansStored Qualitative Scans

Qual_Database: everyone has a copy

WDS_Scans: Change Working Directory to /export/home/spilde

Change Working Directory to get to WDS_ScansChange Working Directory to get to WDS_ScansSelect File and click on “Change Working Directory”

Select /export/home/spilde(be sure Qualitative Analysis is closed before switching)

Be sure to return to your working directory when finished

How to Setup a Qualitative ScanHow to Setup a Qualitative Scan

click on Elem to set specific elements

Set for range (e.g. length of spectrometer) or

Set # of spectra, Channel #, and Crystal

QUANTATIVE ANALYSISThe reason most of us use the probe

• Setup– Setup Quantitative Analysis file first– Then setup Standard Analysis file, if necessary

• Calibrate– Verify that peak position is appropriate– Verify that background counts are reasonable– Verify that Std Variance is low

• Check analysis file– Check the places where you can get tripped up

Quantitative AnalysisQuantitative Analysis

Quantitative Analysis SetupQuantitative Analysis Setup

Work sequentially through the Measurement setup menuWork sequentially through the Measurement setup menu•• Select Correction MethodSelect Correction Method•• Enter Element ConditionsEnter Element Conditions•• Enter EOS ConditionsEnter EOS Conditions•• After calibration, set Standard ConditionsAfter calibration, set Standard Conditions•• If necessary, set Additional FunctionsIf necessary, set Additional Functions•• Save with Conditions StoreSave with Conditions Store•• Then set Stage ConditionsThen set Stage Conditions


Set Material type according to what you are analyzing:Set Material type according to what you are analyzing:•• Select Select OxideOxide for most silicate analysis conditionsfor most silicate analysis conditions•• Select Select MetalMetal for oxygen analysis, metals, sulfides, etc. for oxygen analysis, metals, sulfides, etc. •• Use Use ZAFZAF for most conditionsfor most conditions•• PRZPRZ tends to give better results for light element analysistends to give better results for light element analysis

Correction MethodCorrection Method


To delete, click or drag across elements to select, then To delete, click or drag across elements to select, then ClearClear

Element SelectionElement SelectionClick buttons to selectClick buttons to select


Conditions Conditions specific to this filespecific to this file

““GlobalGlobal”” conditions fileconditions file

Element ConditionsElement Conditions

Element SetupElement Setup

““GlobalGlobal”” file is available to Quant and Standard Analysis, Map, Line, etfile is available to Quant and Standard Analysis, Map, Line, etc.c.You can have multiple setups on the same spectrometer for differYou can have multiple setups on the same spectrometer for different conditionsent conditions


After element entry, click on After element entry, click on Peak overlap buttonPeak overlap button


Always check Always check ““Peak OverlapPeak Overlap”” window. Red highlighted entries are critical.window. Red highlighted entries are critical.


Higher order Ca peaks Higher order Ca peaks interfere with P peakinterfere with P peak

““DifferentialDifferential”” vsvs. . ““IntegralIntegral”” modemode

Diff mode w/ 4 volt windowDiff mode w/ 4 volt window

Int mode

Diff mode

Diff mode filters out interference

Quantitative Analysis SetupQuantitative Analysis SetupCalculated elements setupCalculated elements setup

Hydrated mineral setupHydrated mineral setupEx: Ex: jarosite jarosite KFeKFe33(SO(SO44))22(OH)(OH)66

Carbonate mineral setupCarbonate mineral setup

CO2 is calculated by CO2 is calculated by atomic ratio to the 3 atomic ratio to the 3 anions of oxygen.anions of oxygen.

Quantitative Analysis SetupQuantitative Analysis SetupEOS (Electron Optics) setupEOS (Electron Optics) setup

For constant beam current, click For constant beam current, click check box and then enter value in check box and then enter value in Auto windowAuto window

Expand beam for unstable Expand beam for unstable mineralsminerals

Beam stabilizer is set here if Beam stabilizer is set here if desired (CL or CL & Tilt)desired (CL or CL & Tilt)

Make sure beam scan is off!!!Make sure beam scan is off!!!

Quantitative Analysis SetupQuantitative Analysis SetupAdditional Function setupAdditional Function setup

For overnight runs involving 100For overnight runs involving 100’’s s of analyses, run peak search of analyses, run peak search every 100 or so analysesevery 100 or so analyses

For fairly constant compositions, For fairly constant compositions, background measurements are background measurements are not needed at every pointnot needed at every point

Set overlap correction for VSet overlap correction for V--Ti, Ti, CrCr--MnMn, Mo, Mo--S, etc.S, etc.

Software measures the contribution to Software measures the contribution to Mo from S and corrects for the overlapMo from S and corrects for the overlap


Larger red X indicates where Larger red X indicates where saved point is set (where stage saved point is set (where stage will move to)will move to)

Stage ConditionsStage Conditions

X

Small star indicates current Small star indicates current positionposition

Focus on point and hit Focus on point and hit Read & ApplyRead & Apply to record to record pointpoint

Use down arrow to move to Use down arrow to move to new pointnew point

Use Use MoveMove button to move button to move to recorded positionto recorded position


Select Select Line SetLine Set to set line traverseto set line traverse

Stage Conditions: Line TraverseStage Conditions: Line Traverse

Move to starting point and select Move to starting point and select ReadReadMove to ending point and select Move to ending point and select ReadRead

Set points in between start and stop by Set points in between start and stop by number of points or distance between pointsnumber of points or distance between points





Standard Analysis SetupStandard Analysis Setup

Make Make absolutely sureabsolutely sure that you are entering the right values:that you are entering the right values:If Standard Type is set for oxide, enter oxide values in composiIf Standard Type is set for oxide, enter oxide values in composition window.tion window.If Type is set for metal, enter elemental values in composition If Type is set for metal, enter elemental values in composition window, window,

including oxygen.including oxygen.

Standard CompositionStandard Composition


Make sure that your calibration setup is correct:Make sure that your calibration setup is correct:Calibrate each element on the same spectrometer and crystal as tCalibrate each element on the same spectrometer and crystal as the analysis filehe analysis fileThe PHA conditions must be the same for calibration and analysisThe PHA conditions must be the same for calibration and analysis

Other conditions may vary between standard and analysis setup fiOther conditions may vary between standard and analysis setup files:les:Counting times can be differentCounting times can be differentBackground positions can be differentBackground positions can be different

Standard Analysis SetupStandard Analysis Setup

Do these agree between standard & analysis setups?

Correct spectrometer?

Right crystal?

PHA conditions the same?





Standard AnalysisStandard Analysis

Use Peak Search Monitor (Analysis menu) to inspect peak positionUse Peak Search Monitor (Analysis menu) to inspect peak positions s during calibrationduring calibration

•• Open the Peak Search Monitor ONLY before you start calibrationOpen the Peak Search Monitor ONLY before you start calibration•• If the resulting peak is not on the peak If the resulting peak is not on the peak centroidcentroid, redo the, redo the searchsearch

CalibrationCalibration

Standard AnalysisStandard Analysis

Look at your calibration (possibly save for later reference)Look at your calibration (possibly save for later reference)•• Check accumulated values. Are there significant deviations?Check accumulated values. Are there significant deviations?•• Check Standard Variance (S.V.). IdeallyCheck Standard Variance (S.V.). Ideally 0.5% or less.0.5% or less.•• Check backgrounds. If one is significantly higher (2X), double cCheck backgrounds. If one is significantly higher (2X), double check your heck your

background positions for interferingbackground positions for interfering peaks,peaks, such as Ksuch as K. . •• Compare with previous calibration. Did peak position or count raCompare with previous calibration. Did peak position or count rate change?te change?

After CalibrationAfter Calibration

Standard AnalysisStandard AnalysisAfter CalibrationAfter Calibration

If S.V. isIf S.V. is too high, select too high, select Check DataCheck Data to remove bad datato remove bad data

Click Click AcmAcm buttonbutton

Then click on Then click on standard standard accumulationsaccumulations

Unselect values that deviate significantly Unselect values that deviate significantly from the average, then from the average, then SaveSave



• Check analysis file– Watch the places where you can get tripped up



If the standard that you just calibrated does not appear in the If the standard that you just calibrated does not appear in the list, make sure list, make sure STD Group STD Group ““AllAll”” is selected. If you still cannot see the standard that you is selected. If you still cannot see the standard that you calibrated, you have probably calibrated the element on the wroncalibrated, you have probably calibrated the element on the wrong spectrometer g spectrometer or at the wrong conditions (20 kV when you meant to use 15 kV).or at the wrong conditions (20 kV when you meant to use 15 kV).

Places where you are going to get tripped upPlaces where you are going to get tripped up

Open Open Standard ConditionStandard Condition window window and make sure that the correct and make sure that the correct standards are selected. If not, open the standards are selected. If not, open the Standard Data for that element and Standard Data for that element and select the right standard.select the right standard.


Open Open Element ConditionsElement Conditions window window and verify that all Peak Positions have and verify that all Peak Positions have been updated.been updated.

Places where you are going to get tripped upPlaces where you are going to get tripped up

If peak has not updated, open global If peak has not updated, open global element window for that element and element window for that element and click click OKOK

Old peak position

New peak position

Documents

Become a Microprobe Power User Part 2: Qualitative & …meteorite.unm.edu/site_media/pdf/Microprobe Poweruser Part 2.pdf · The reason most of us use the probe ... Map, Line, etc