Cameca SXFive Electron Probe Microanalyzer Operating

Instructions

Figure 1: Cameca SXFive EPMA

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Contents

1 Introduction 3

2 Hardware 32.1 Computers/Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1.1 Login . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.1.2 Remote Operation and Data Transfer . . . . . . . . . . . . . . . . . . . . . . . 3

2.2 Energy-Dispersive X-ray Spectrometer (EDS) . . . . . . . . . . . . . . . . . . . . . . . 32.3 Electron Column . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 Wavelength-Dispersive Spectrometers . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.5 Optical Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.6 Manual User Interface/Knobset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.6.1 Multi-function Roller Wheels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.7 Vacuum System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.8 Chiller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.9 Electronics Cabinet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72.10 Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 Sample Exchange 83.1 Sample Holders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.2 Sample Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83.3 Sample Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4 Sample Navigation 10

5 Electron Column Setup 115.1 Beam On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.2 Auto Column Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.3 Manual Column Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.3.1 Objective Aperture Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . 125.4 Focus and Stigmation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.4.1 Focus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.4.2 Stigmation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6 Spectrometer Setup 136.1 Crystal Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.2 Spectrometer Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.3 Peak Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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1 Introduction

The Cameca SXFive is an electron probe microanalyzer. It has five wavelength-dispersive spectrome-ters with six different crystals allowing elemental analyses from B to U. The stages can accept standardgeological thin sections or 1” mounts. All samples must be well polished and carbon coated.

2 Hardware

2.1 Computers/Monitors

The EPMA system is controlled by two computers. One PC for the Cameca SXFive (SX-960, belowthe desk) and the other PC (Thermo, behind the monitors) to operate the EDS and Probe for EPMA(PfE ) software. Both computers have network connections and can be accessed remotely for operationand data transfer. There are two banks of monitors, the upper set is connected to the SX computer,the lower to the PfE. A single mouse and keyboard controls both computers across the all six monitors.A separate monitor beside the column for electron imaging is not accessible remotely.

2.1.1 Login

• The user account for the SX-960 computer is SX, the password is sx.

• There is no login for the Thermo Scientific computer.

2.1.2 Remote Operation and Data Transfer

• RemotePC : Please contact the BSCSC lab manager for remote access permissions to the EPMAcomputers via RemotePC.

• Data transfer: No USB drives shall be used to transfer data. All data transfer shall be accom-plished using the network, either by email, shared drives, a cloud service (e.g. Dropbox) orRemotePC.

2.2 Energy-Dispersive X-ray Spectrometer (EDS)

The EPMA has a Thermo Scientific UltraDry 10mm2 silicon-drift energy-dispersive x-ray spectrometer(EDS). The EDS runs on the Thermo Scientific computer (lower bank of monitors). The EDS canbe controlled via the Thermo Scientific Pathfinder software or through the PfE software (e.g. forcombined EDS/WDS analyses).

2.3 Electron Column

The SXFive has a CeB6 source. This source can be switched out for a tungsten filament if there areissues with the beam.

2.4 Wavelength-Dispersive Spectrometers

The SXFive has five wavelength-dispersive spectrometers. Spectrometers 2-5 have two large area crys-tals (denoted by the L prefixes) and spectrometer 1 has four smaller area crystals. The spectrometerconfiguration is as follows:

• Spectrometer 1 - TAP, PET, PC1, PC2

• Spectrometer 2 - LTAP, LPET

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• Spectrometer 3 - LPET, LLIF (High pressure)

• Spectrometer 4 - LPET, LPC0

• Spectrometer 5 - LPET, LLIF (High pressure)

The characteristic x-rays that can be detected by each crystal are shown in Figure 2.

Figure 2: Cameca SXFive crystals

2.5 Optical Camera

The optical camera can be viewed in the SX-Control ’s Camera window (Figure 3). In the Camerawindow the user can autofocus (Z Focus), change the optical camera zoom of field of view (FOV ),select reflected (Refl.) or transmitted (Trans.) light and toggle polarization (Pola.) on and off. Therotation of the polarizers relative to the sample is manually controlled on the lower left side of thecolumn (Figure 4). The illumination of the lighting is automatic but can be overridden using thedropdown in the upper left of the window. The camera window also displays the beam or absorbedcurrent and the stage coordinates.

The beam will be visible on a fluorescent sample (e.g. benitoite). The beam should be coincidentwith the crosshairs. If the beam and crosshairs are not coincident please inform the lab manager.

2.6 Manual User Interface/Knobset

The manual user interface (MUI) or knobset (figure 5) can be used to control a number of differentmicroscope functions:

• Dedicated coarse and fine magnification.

• Dedicated coarse and fine focus.

• Stage X, Y, and Z movement.

• Beam scan rotation.

• Beam Scan/Fix (raster or spot modes).

• Beam on/off (Faraday cup out/in).

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Figure 3: SX Control camera window

Figure 4: Polarizer adjustment

• Autofocus.

• X-ray ratemeter.

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Figure 5: Manual User Interface (MUI)

2.6.1 Multi-function Roller Wheels

The functions of roller wheels 1-4 on the MUI (figure 5) can be set in the lower part of the Rollersection of the SX Control window (figure 6). Clicking on the Choice button will allow you to select anumber of functions including beam settings, electron image settings and optical settings.

Figure 6: Roller Window in the SX Control Interface

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2.7 Vacuum System

The vacuum system consists of a dry-scroll pump (housed behind the unit), a turbo-molecular pump(below the column) and an ion pump (attached to the gun). The vacuum status is indicated in theVacuum and Vacuum Synoptic tabs of the SX-Control window and also on the lower front of theelectronics cabinet.

2.8 Chiller

The chiller should be running during normal operation. If the chiller is off or displaying warninglights, check the water level in the reservoir. If the level is low please inform the lab manager.

Figure 7: Chiller unit display panel

2.9 Electronics Cabinet

Two green lights should be illuminated on the upper right of the electronics cabinet during normaloperation (figure 8). The key should be in the ON position. If either of these lights are out, pleaseinform the lab manager.

2.10 Gases

The EPMA uses dry nitrogen for venting the vacuum system. P10 gas (90% argon, 10% methane) isused in the gas flow proportional counters. If the spectrometers are not detecting x-rays, or the countrates are extremely low, check the gas bubblers in the lower rear of the column unit (figure 9). Theflow rate should be approximately one bubble per second.

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Figure 8: Electronics cabinet lights and key

Figure 9: P10 gas bubblers

3 Sample Exchange

3.1 Sample Holders

Two samples holders are available for the EPMA, one holder takes two thin sections and two 1”diameter mounts (HOTS2+2). The other holder takes 6 1” diameter mounts (HO6). There is a singleshuttle to which the sample holders attach using 4 screws.

3.2 Sample Loading

• Load the shuttle onto the two rails and push until it clicks (you should not be able to removethe shuttle by pulling).

• Close the airlock door until it clicks.

• Click on the Vacuum tab in the SX Control window. Select In. A pop up window will ask ifthe airlock door is closed, if so, click OK. The airlock will now be pumped and a message willinform when the vacuum is ready.

• Once the airlock is pumped, open the gate valve by pushing the black lever up along its axis(step 1 on Figure 10) then pulling upwards (step 2).

• Make sure the black collar around the sample insertion rod is turned so that the arrow pointsin towards the chamber (figure 11).

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Figure 10: Procedure to open gate valve

Figure 11: Sample loading collar position

• Push the sample insertion rod in all the way until it stops. Remove the rod, pulling all the wayout to the end. The stage/shuttle should now be left inside the chamber.

• Close the gate valve by twisting the black knob to horizontal (step 1 on Figure 12) then pushingdown (step 2).

• Right-click on the optical image and select Reference-Move to. This will move the stage to thex=0, y=0, z=0 reference point. The reference point on the sample holder is the intersection of

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Figure 12: Procedure to close gate valve

two crosshairs. If the stage crosshairs do not align with the camera crosshairs, double-click thestage crosshairs on the image to center them. Right-click on the image and select Reference-Update.

3.3 Sample Removal

• Click on the Vacuum tab in the SX Control window. Select Out. The stage will drive to theairlock position. If the airlock is still under vacuum a window will prompt you to open the gatevalve.

• Open the gate valve (black knob)

• Make sure the black collar around the sample insertion rod is turned so that the arrow pointsaway from the chamber (figure 13).

• Insert the sample rod all the way to retrieve the shuttle.

• Withdraw the rod all the way to the end, the sample shuttle should now be in the airlock.

• Close the gate valve by twisting the knob to horizontal then pushing down.

• Click OK in the window, this will initiate venting of the airlock.

4 Sample Navigation

• Joystick: The joystick can be used to move the stage in the X and Y directions. In addition theright button (AF ) initiates the Z autofocus.

• Camera Window: Double-clicking on a point in the camera image will center that point in theframe.

• Stage/Roller Window: The Stage/Roller window will display the selected sample holder. Double-clicking on the area of interest will drive the stage to the selected point.

• Manual User Interface (MUI): The MUI X,Y, and Z roller wheels can be used to navigate thesample.

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Figure 13: Sample removal collar position

5 Electron Column Setup

5.1 Beam On

• In the Beam panel (figure 14) select or enter an accelerating voltage in HV (kV).

• Select or enter a beam current (I (ηA)). The regulation will be turned on when you enter abeam current. Regulation is a feedback mechanism to minimize beam current drift.

• Select a beam diameter if required (Size (µm)). Note that if the beam has a diameter otherthan zero, you cannot focus/stigmate the beam.

5.2 Auto Column Alignment

• Move the stage to a cathodoluminescent sample (e.g. benitoite).

• Select a beam spot size of 0.

• Select Auto Align in the Beam panel.

• Once the alignment has completed check the alignment using the coarse focus knob to movethrough the plane of focus. The spot should not shift but simply go in and out of focus. If thebeam shifts it may be necessary to perform a manual alignment.

5.3 Manual Column Alignment

• Move the stage to a cathodoluminescent sample (e.g. benitoite).

• Select a beam spot size of 0.

• Choose a low beam current of approximately 5ηA (the exact value does not matter). The SXFivecannot beam regulate at such low beam currents, turn on Measure in the Beam tab to checkthe actual value with the Faraday cup in (Beam - Cut).

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Figure 14: Beam panel in SX Control window

• Degauss the beam using Hysteresis in the Beam More tab.

• Turn on the beam and place on a recognizable feature.

• Increase the beam current to 200-300ηA.

• If the beam shifts select Alignment in the Roller window (6) and adjust the Gun XLO and GunYLO to recenter on the point of interest.

• Repeat to check the alignment.

5.3.1 Objective Aperture Alignment

• Move the stage to a cathodoluminescent sample (e.g. benitoite).

• Select a beam spot size of 0.

• Using the MUI, adjust the coarse or fine focus knobs to move back and forth through the planeof focus.

• If the image shifts select the Aperture option from the Choice button in the Roller window

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• Using roller wheels 3 and 4 adjust the X Aperture and Y Aperture to minimize the beam shiftwhen moving through the plane of focus.

5.4 Focus and Stigmation

5.4.1 Focus

Focus can be adjusted using the coarse and fine focus knobs on the MUI. Note the spot size must beset to zero in order to adjust the focus. If the image does not focus well and stretches when movingthrough the plane of focus, the beam is astigmatic and requires adjustment.

5.4.2 Stigmation

• Reduce the beam current (e.g. 5ηA) and ensure the regulation is off.

• Select the Stigmator option from the Choice button in the Roller window

• Increase the amplitude (Asti amp), this makes any changes obvious.

• Adjust the angle to minimize the image stretching.

• Reduce the amplitude (Asti amp).

• Re-adjust the angle (Asti Ang).

6 Spectrometer Setup

6.1 Crystal Selection

The crystals for each spectrometer can be selected in the WDS field of the SX Control window (Figure15). Click on the dropdown in the Crystal field to select the crystal. To check which elements can bedetected with a given crystal click on the icon in the Ray Position field. This opens a periodic tablewindow indicating which elements and lines are available for the selected crystal.

6.2 Spectrometer Verification

After switching crystals on a spectrometer, due to hysteresis in the spectrometer and crystal turretmotors, the spectrometer will need to be verified. The verification process involves performing a peaksearch on the verification element for the given crystal, once the peak is acquired the software notesthis peak as the theoretical peak position. In the WDS pane of the SX Control window an unverifiedspectrometer position will be highlighted in red. Figure 15 shows the WDS window, in this casespectrometer 2 is not verified. The elements used for the different crystals are:

• TAP - Si

• PET - Ca

• LIF - Fe

• PC0 - O

• PC1 - O

• PC2 - O

To perform spectrometer verification:

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• Move to a sample containing the verification element for the crystal of interest. the RV (RobertsVictor) garnet contains all of the verification elements for all the installed crystals.

• Optically focus the sample.

• Select the spectrometer(s) to be verified (Sp1, Sp2..).

• Select Verify On Current Position. The spectrometer will be verified and the Ray Position willno longer be highlighted in red.

Figure 15: WDS spectrometer window

6.3 Peak Search

To perform a element peak search:

• Select the spectrometer to be used in the WDS window of the SX Control window (figure 15).

• Click the Ray Position icon under the appropriate spectrometer.

• Double-click the element of interest in the pop-up periodic table. The spectrometer will moveto the theoretical peak position for the selected element x-ray line.

• From the peak search dropdown menu select - Fine Search, Wide Search, or Wide, then FineSearch. The results of the peak search will be displayed in the Spectrum window in the lowerright of the SX Control window.

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