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ENERGY DISPERSIVE X-RAY SPECTROMETRY

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Introductory DiagramEnergy Dispersive X-Ray Spectrometry: EDS Instrumental & Signal DetectionX-Ray DetectorsDetector EfficiencyThe Geometrical EfficiencySignal ProcessingPreamplifierThe Signal ProcessorMultichannel AnalyzerEnergy ResolutionCollimationReferencesX-Ray Signal GenerationSignal OriginSpatial ResolutionDirection of SignalsAnalysis of Rough Surfaces or ParticlesgraphImportant EDS ParametersEDAX Detector GeometryDead Time & Time ConstantsEDX Spectrum Interpretation & ArtifactsContinuum X-RaysCharacteristic X-RaysDepth of ExcitationX-Ray AbsorptionX-Ray FlourescenceDetector EficiencyX-Ray ArtifactsPeak BroadeningPeak Distortion/AsymmetryEscape PeaksAbsorption EdgesSilicon Internal Flourescence PeakSum PeaksStray RadiationA Warming DetectorEDAX Phoenix Peak IdentificationPeak IDCharacteristics of the K-SeriesCharacteristics of the L-SeriesCharacteristics of the M-SeriesAuto Peak IDpage 1page 2Devolution and Peak IDEDAX Peak ID QuizQuiz page 1Quiz page 2EDAX Peak ID Quiz AnswersQuiz Answers page 1Quiz Answers page 2X-Ray Count Optimization of X-Ray Count ThroughputOptimization graphSEM Quant ZAFGeometrySetup PresetLabels and Add TextPeak IDHPDSaving Quantification DataPrintingSpectrum OverlayCalibrationQuantitative X-Ray Analysis using ZAFQuantitative Analysispage 1page 2page 3Analysis with Compound StandardsIntroductionThe Compound StandardSEC FactorsSEC Factors ContinuedTableAnalysis with Pure Element StandardsPure Element Standards SetupProcessing Unknown SpectraSaving a Compound Standard as a Pure Element TableAnalysis with SEC FactorsImage Mapping BasicsImaging/MappingImage Collect/External XYIntegrated FramesOverlay MapsReverse PaletteZoom and Measure on ImagePixel SizeOverlay MapsZoom and Measure on ImageThe line measurement tool button lies to the right of the zoom button. Clicking on the line measurement tool will move the selected image to the 1_view mode and the cursor will turn into crosshairs.Click on the first point of the line to be measured and drag to the end point. The measurement will be given in blue text in the status bar at the bottom of the screen.The measuring unit is micron.To measure another line simply click on the measurement button again.Annotating the ImagePrintingLine ScanMulti Point Analysis BasicsSEM Multi Point AnalysisLinescanPrintSpectrum Mapping BasicsCollecting Spectral MapsDisplaying MapsRecalling Spectral MapsCreating SpectraCreating Linescans from Recalled DataCreating Quantitative MapsPrintSpectrum UtilitiesIntroduction to Digital ImagingIntroductionIntroduction ContinuedSummary of EDAXEDAX Phoenix Procedures - PhotoImpactIntroductionProceduresTo Open an ImageChanging Brightness and ContrastTo Change Image ModeTo Create a 3D Anaglyph Image from a Stereo PairSetupProcedureTo Overlay Text on the ImageTo Overlay Spectrum on the ImageTo Creat Thumbnails of the Images and other Album ProceduresReport Writing with Microsoft OfficeInserting in MS ExcelInserting in MS WordInserting Quantitative Results into a ReportUsing BMP or TIF filesEDAX Auto/Mulit-point Analysis SoftwareSoftware exampleAnaglyph Color Stereo Image with PhotoshopTo Create an Image - Method ITo Create an Image - Method IIEDAX Phoenix Training Course –Introductory Diagrams - page 1EDAX Phoenix Training Course - EDS Instrumentation & Signal Detection - page 1ENERGY DISPERSIVE X-RAY SPECTROMETRY--EDS INSTRUMENTATION & SIGNAL DETECTIONALAN SANDBORGEDAX INTERNATIONAL, INC.1. X-Ray Detectors:The EDS detector is a solid state device designed to detect x-rays and convert theirenergy into electrical charge. This charge becomes the signal which when processedthen identifies the x-ray energy, and hence its elemental source.The X-ray in its interaction with solids, gives up its energy and produces electricalcharge carriers in the solid. A solid state detector can collect this charge. One of thedesirable properties of a semiconductor is that it can collect both the positive andnegative charges produced in the detector. The figure below shows the detectionprocess.Figure 1.There are two types of semiconductor material used in electron microscopy. They aresilicon (Si) and germanium (Ge). In Si, it takes 3.8 eV of x-ray energy to produce acharge pair, and in Ge it takes only 2.96 eV of energy. The other properties of these twotypes will be discussed later in this section. The predominant type of detector used isthe Si detector, so it will be favored in the discussions. With a Si detector, an O K x-raywhose energy is 525eV will produce 525/3.8= 138 charge pairs. A Fe K x-ray willproduce 6400/3.8= 1684 charge pairs. So by collecting and measuring the charge, theEDAX Phoenix Training Course - EDS Parameters - page 1Important EDS ParametersCount RateFor a good quality spectrum (i.e. good resolution and fewest artifacts) you should use the50 or 100 us time constant (pulse processing time) with a deadtime of 20 to 40%, and 500to 2500 cps.These are good numbers if the sample consists largely of high energy peaks (>1 keV), but if the spectrum is dominated by low energy peaks (< 1 keV) then a count rate of500 - 1000 cps is better and the 100 us time constant should be used.When maximum count throughput is required, such as when collecting fast x-ray maps, afaster time constant (2.5 to10 us) should be used with a count rate of 10,000 to 100,000cps. The deadtime should not exceed 50 to 67%. These conditions may not be optimum forlow energy peaks in terms of their resolution and/or position. A lower count rate and slowertime constant should be and/or it might be necessary to adjust the position of the ROI priorto collecting the map.Accelerating VoltageThe overvoltage is a ratio of accelerating voltage used to the critical excitation energy of agiven line for an element. Typically, the overvoltage should be at least 2 for the highestenergy line and no more than 10 to 20 times the lowest energy line of interest. We use thenumber 10 for quantitative applications and the 20 for qualitative applications.For example, if you are interested in analysis of a phase containing Fe, Mg and Si and wantto use the K lines for each, then 15 kV will probably work reasonably well. If, however, youneed to analyze the same three elements plus oxygen as well, then you might use 5 to 10kV, but you might want to use the L line for the Fe.Why should the overvoltage be at least 2 for the highest energy element? Because at lowerovervoltages the fraction of the interaction volume where the element can be


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