LEO Jon Paul Johnson’s Montage Ductile Iron Images

LEO Technical Objective To train you to use the electron microscopes on lower campus Start with the Leo 440i –We control it! –It’s currently running –Once you have learned the concepts on one microscope, in principle everything else is “knobololy” (Figuring out where the knobs are that control the feature you want to use.)‏ –It’s not easy or expensive to break (please don’t prove me wrong!)‏

LEO Vac-ion Pump Column “Upper Valve ” Chamber —10 -7 Torr Column Valve Electron gun Turbo- molecular pump —10 -8 Torr 760—10 -3 Torr Stage Sample Penning gage Oil Filter Exhaust Pumping system for Leo W-filament SEM (actually LaB 6 )‏ Oil-sealed Rotary Mechanic al Pump

LEO Leo 440i SEM Column Electron gun Aperture adjustment micrometers Chamber valve Upper valve Turbomolecular pump behind here

LEO Leo SEM: rear of column Vac-ion pump Everhard- Thornley Detector Gun

LEO EDS side of SEM LN2 tank Beam blanker

LEO Oil-sealed rotary mechanical pump

LEO Administrative matters Nothing in life is free Log onto the SEM with the sheet on the desktop Enter your name Enter the name and contact information of whoever will be paying Record how many times you coated samples Click on “View/Status”. Enter the filament lifetime when you start. Enter the time of day when you start. Repeat the last two steps when you finish.

LEO Notes on the computer The SEM is about 15 years old. It runs on a 66 MHz 486 under Windows Plan on having to reboot at least once per day. In windows 3.11 you cycle among active applications with ALT TAB. (Hold down ALT; every time you hit TAB, it cycles one application.)‏

LEO Getting started with the Leo Typical conditions when you walk in: –Ion pump is running –Chamber is under vacuum –“Upper valve” (gun valve) is closed –Column valve is open –All pumps are running

LEO Sample Mounting Leo uses mounting stubs with 1/8” shafts Carbon tape (double sticky) is simplest Carbon dots have lower vapor pressure Multiple samples can be mounted on turret Make a drawing in your research notebook of the locations of your samples on the turret Single mount is easiest for tilting Vertical mount is also an option Tighten gently with Allen wrench; ditto for sample holder on stage

LEO To insert your sample Check vacuum –Stage/vac –Vacuum status Chamber pressure should be – Torr Column pressure should be few x Torr Close column valve Vent (Stage/vac, Specimen change or right yellow arrow)‏ Insert sample. Remember where samples are! Close and latch door. Do not overtighten! Pump (Stage/vac, Specimen change or right yellow arrow)‏ After the pressure goes below Torr you may open the column valve and turn on the beam.

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Drop Down List Box and Tool Bar (nearly all SEM functions are mouse-controlled)‏ Beam on Beam off Standby Pump Vent Vacuum control Left mouse buttonMiddle mouse button Roll mouse left to decrease value Roll mouse right to increase value Alternatively, double click on a box to enter data directly

LEO Go! Turn on beam Turn up brightness Hopefully you will see something Optimize beam Backup plan –If you fail to get an image, under File/(run) Standard! These are factory-installed parameters

LEO Decide on operating parameters 40 kV for highest resolution 20 kV for EDX Low voltage for optimum topography and least damage 100 pA for good resolution 300 pA for EDX for better signal-to-noise 25 mm WD for EDX 7 – 8 mm WD for maximum resolution

LEO Center of Stage (Red square)‏ Beam location (Blue square)‏ Cursor! Stage will move in direction of arrow when left mouse button is depressed Speed increases with distance cursor is from beam

LEO Use when OptiBeam is off OptiBeam on

LEO Pictoral explanation of gun shift Filiment Gun tilt lens aperature With the gun shift centered, the electron beam heads straight down the column. The image is brighter and can also be focused better. Otherwise the image moves when you change focus.

LEO Center filament image with “Tilt” option

LEO Adjust beam shift when OptiBeam is turned on

LEO Voila! An image!

LEO Optimize image Start with low magnification Look for dirt or some large feature Move feature to center of screen Go to reduced raster…Why? Focus Increase magnification…preferably 2-5X what you will use for the image you record. Why? Focus Iterate Full screen image

LEO Saving an image Get good quality image –2 minute scans over a few kX –Faster scans at lower magnification Under “Image/Noise reduction”, click on “Freeze at end”

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Saving images, cont’d Under “File/Export tiff”, choose e:\ as the destination. The E:\ drive is mapped to the support PC that is next to the machine. From this machine you can use a USB memory stick or transfer files through the internet-- web mail or file transfer.E:\ Enter a filename: 6 characters (related to your sample) + 2-digit counter (00)‏ All students need to bring their own USB stick; files are approximately 1 MB

LEO Check “Export/Photo setup” to assure it is not set to “HRRU”!