Philips XL30 FEG SEM - Michigan Center for Materials
Contents
1. MB TIFF 1404 x 968 pixels e Databar Click on Databar under the In Out menu and enter or delete items by clicking on the appropriate check boxes There is also a 28 character user box at the top of the dialogue box which can be filled with relevant information When completed click on OK date updated May 2000 6 ELEMENTAL ANALYSIS There is an EDX detector attached to this microscope You can use it to determine what elements are in your sample The software will allow you to collect spectra and do semi quantitative composition analysis from particular places on your sample You can also do elemental mapping to show the distribution of particular elements The kV used will determine what elements you will see Heavier elements will generally require higher kV The software will show you at what energy eV peaks will be for different elements The incoming kV must be higher than any peak you hope to see preferably almost 2 times higher The interaction volume for x rays is MUCH larger than the spot size It depends on the energy of the incoming electrons i e the beam voltage and the atomic weight of your sample Use the program Electron Flight Simulator to run a Monte Carlo simulation and find out the interaction volume and therefore the possible resolution of any elemental analysis you will do e You will need to be at eucentric height i e Working distance 10mm e Go to Program Manager Open Folder EDAX e Use pro2. and minus keys double and halve respectively You may need to refocus as you increase the mag date updated May 2000 OPTIMIZING THE IMAGE Once the image is obtained it might need further optimization before it is stored on disk or printed e Magnification and Spot size Optimizing the image involves choosing a suitable area of the specimen and also the relative magnification to suit the structure observed Spot size should be adjusted to a smaller size for high mag and larger at low mag Judging which spot size is correct for a particular magnification relies on the ability to focus well and correct astigmatism easily at the chosen magnification e Focusing right mouse button Use the focus control with the mouse to correct the sharpness of the image Focusing at 2x 3x the magnification needed for the final result will make the lower magnification sharper e g photo mag 2000x therefore focus at mag 4000x 8000x Focus using either total screen in TV scan or the selected area window at a slower scan rate for a sharper image You can change both the size and position of the window with the left mouse button Click and hold inside the window to drag it to a new position Click and hold outside the window to open a new window drag to the desired size before releasing the mouse button e Aperture Centering If the image moves when changing focus the aperture needs centering Make sure you have the settings group of cont
3. radiation effects can not be eliminated if radiation doses are kept below the occupational dose limits These effects are stochastic which means that the probability of the effect is a function of your total radiation dose That is you are more likely have a radiation induced effect if you have high radiation doses This is a result of the non threshold dose response relationship THE NON THRESHOLD DOSE RESPONSE RELATIONSHIP This relationship is an assumption based on some good science that is used to estimate risks that can not be directly measured This graph implies that all radiation doses have some risk The amount of this risk is very low for very low doses but is not zero Some would say that there is no safe radiation dose This is a misrepresentation There are radiation doses with negligible risk I would say that something with a very low risk is safe STOCHASTIC PROBABILISTIC RADIATION EFFECTS Cancer 3 10 000 chance of cancer per rem Normal cancer rate 25 33 date updated May 2000 11 Genetic Effects 5 75 1 000 000 genetic disorders per rem Normal genetic disorder rate of 10 No radiation genetic effects have ever been demonstrated in human populations Latent period Radiation induced cancers occur after a latent period has elapsed This latent period is gt 30 years for most cancers 2 years for leukemia Fetal Radiation Effects The fetus and children are 5 10 times more sensitive to radi
4. The Philips FEG SEM Handbook l i i l p g J Taj vd ie i pe i I ag 7 n te i l k i B nan a _ The Philips FEG SEM Handbook This section adapted from the Philips User Manual chapter 4 This chapter describes the basic operation of the microscope involving several steps to achieve hard copy results or image transfers to disk It is assumed that the instrument has been started up and brought to a waiting condition ready for inserting a specimen INSERTING A SPECIMEN Put on some gloves Turn off the HT the high voltage The button should be gray If the HT is on button yellow turn it off by clicking on the button Open the chamber Vent the chamber with dry nitrogen Click on the VENT button You will hear the Nitrogen gas turn on after a short delay needed to verify that the high tension is off security HT interlock After a couple of minutes you will be able to open the chamber Eventually the microscope will say idle Load a specimen Set Height Using gloves and or tweezers place the sample stub into the stage specimen holder Secure the specimen stub with an appropriate Allen key Set the sample height to 10mm eucentric height with the height guide First loosen the cone at the bottom counter clockwise then adjust the upper part until the top of your sample is level with the 10mm mark on the height guide Tighten the cone Ad
5. ance Do NOT click anything yet You can move the window out of the way but do not hit ok or cancel You can use all the other microscope controls like contrast brightness x y stage motion and focus while this window is open This window is asking you to calibrate the stage z height After you load a sample the stage does not know how far away the sample top is from the bottom of the pole piece If you tell the computer to change z height it is VERY likely you will CRASH into the pole piece or the BSE detector if it is installed You must focus the sample first The microscope knows how far away the objective lens focal point is from the pole piece When the sample surface is in focus the focal point is on the surface of your sample Therefore the WD in the databar is a measurement of the true working distance So move the window out of the way find the tallest part of your sample the bit that will crash first and focus it at around 200x magnification or better Then you can click on OK You should see the information from the Objective lens WD in the databar be loaded into the z height over in the stage window You cannot tell the stage where it is in any other way Do not attempt to type in your estimate of the working distance while the stage is not calibrated because the stage will simply try to move there from it s present assumed position i e CRASH There is no cancel button and ther
6. ation induced cancers than an adult Teratogenic effects are also possible at very high doses The magnitude of your radiation risk is dependent on your total radiation dose HISTORICAL RADIATION DOSES FOR ELECTRON MICROSCOPISTS The typical measured radiation dose at the Material Science Space Physics Research Laboratory is M This M refers to less than the minimum detectable amount of the badge These badges are capable of measuring 0 01 rem per month The annual dose limit for normal adults is 5 rem per year Clearly your radiation dose is expected to be very low Why is training required for this low risk The State of Michigan requires this training of electron microscopists and stringently reviews the training records The regulations which govern the use of electron microscopes were developed in the past prior to 1970 when poorly designed units could cause significant radiation fields Obviously old machines and significantly modified machines could have the safety deficiencies that these regulations are intended to protect against PROTECTION METHODS External versus Internal Radiation Exposure The radiation exposure comes from an x ray machine No radiation lingers after the machine is powered down There is no risk of radioactive contamination from an x ray machine Thus there is no need for special procedures are required for wearing personal protective equipment Protection Techniques Time Minimize time near sources W
7. e is no are you sure window Be very careful when you use the computer to change z height date updated May 2000 3 e Correct the contrast and brightness if necessary Use either the controls found at the bottom of the Beam Control group or on the Video control group of the Control Area Imaging To set Contrast and Brightness set contrast to zero and brightness to zero Increase brightness to the point at which the screen just turns from black to gray Then set the contrast to approximately half the brightness value e Focus the sample right mouse button Correct the focus using the right mouse button until the image is sharp Hold the right mouse button down and move it from side to side to find the best focus e Move the specimen to the area of interest Manually with the X Y knobs on the front of the chamber door TRACK two circles on screen cursor is target You set the direction and speed of stage movement with the left mouse button GET cursor is a cross and you double click on a region to center it At low mag this is done with stage movement At high mag this uses beam shift SHIFT only used at high magnification Cursor is a hand and you change the region of view by dragging the beam shift with the left mouse button ARROW KEYS the arrow keys on the keyboard will also move the specimen stage e Change the magnification Set an appropriate magnification using either the magnification menu or using the plus
8. en when nearing correction releasing the mouse button temporarily will reposition the cross hairs in the center of the screen to enable further movement date updated May 2000 5 RECORDING THE IMAGE There are three options for recording the image videoprint save file Polaroid The first two are the most commonly used There are some things you can change before you record the image such as the information shown on the databar the scan speed for recording and whether the image is standard definition or high definition You should also make sure that the magnification shown on the databar is the correct magnification for the image you are recording Magnification menu device videoprint photo screen e Videoprint Choose photo scan speed or another slow scan rate to give a still sharp image Clicking on Freeze under the Filter menu or the Freeze icon button on the Icon Button Bar will freeze the image Choosing integrate 1 under the Filter menu will freeze the image automatically after one scan With the video printer switched on click on the In Out menu then on the Videoprint option A print of the screen display should emerge The databar may be printed on the videoprint if required the magnification relating to the format of the videoprint The video printer will always grab what is seen on the screen therefore all scan rates including TV can be copied This means that care should be taken if a high quality image i
9. gram EDX control for collecting spectra EDX Mapping for determining elemental distribution e Leave the microscope in full screen mode for information about the whole scanning area Use small screen or spot mode to limit the area e Use the stopwatch button just above the spectra window to start and stop a scan Use the wiper roller button to clear the scan From EDX control spectra can be saved as comma delimited text for export to other plotting programs e In EDX Mapping you may have to choose collect Spectrum to bring up the spectrum window which will then appear to be very similar to the EDX control program Ask for a demonstration date updated May 2000 GENERAL GUIDELINES FOR BOOKING THE EMAL MICROSCOPES 1 Do not book time unless you are a qualified user for that particular time period or you will be accompanied by such a user whose name should appear in the Booking file This user will be operating the microscope FOR you NOT training you 2 Book only the time that you think you will need Note that the basic Prime Time weekdays sessions are four hours long If you require less time please indicate in the relevant booking box the amount of time you desire and try to confine these split sessions to the afternoon periods only 3 Sessions not used or canceled with less than 24 hours notice may be charged as if used 4 Booked sessions that are unclaimed 1 2 an hour after the scheduled starting time w
10. hey are to use before they commence use They should appraise themselves of the information in the handbooks paying particular attention to the safety information and then sign the safety section of an EMAL Authorization form OBJECTIVES Promote safety and regulatory compliance REGULATORY ORGANIZATIONS Michigan Department of Public Health The division of Radiological Health regulates the use of x ray producing machines PRESENCE OF RESTRICTED AREAS RADIATION SOURCES e The electron microscopes produce x ray radiation e The x ray producing machines may be identified by the posting on the door of the laboratory the identification markings and stickers on each machine and the registration certificates for date updated May 2000 10 each unit If you have any question about the location of the machines contact your facility supervisor e General procedures describing the use of these units are located on the on the door of each laboratory e Each unit has been surveyed by Radiation Safety Service to ensure that the units do not leak unacceptable amounts of radiation RADIATION BIOEFFECTS Acute versus Chronic effects Acute Short term effects Skin Erythema Like a sunburn Epilation loss of hair Hemopoeitic Death etc These acute radiation effects can be eliminated if radiation doses are kept below the occupational dose limits Chronic Short term effects Cancer and Genetic effects These chronic
11. hey first apply to use Electron Microbeam Analysis Laboratory EMAL instruments if that instrument is a radiation source or if they will be working in a room that contains an instrument that is a radiation source This radiation safety information is appended to the instruction handbooks for all radiation producing EMAL instruments A copy of the handbook for the instrument that the user wishes to use will be given to each new user together with an EMAL Authorization form This Authorization Form has two purposes 1 The users advisor immediate supervisor or the owner of the account against which EMAL use will be charged must sign the form to authorize the said charges 2 The user should familiarize him herself with the saftey information in the Instrument User Handbook including the radiation safety information if the instrument to be used is a radiation source Users should read this safety information before returning the signed EMAL Authorization form Returning the signed EMAL authorization form is an indication that the user has read and understood all of the safety information in the handbook If there are questions and or concerns the user should not sign the form until they have discussed these concerns with John Mansfield or Corinna Wauchope NON UNIVERSITY OF MICHIGAN USERS Non University of Michigan Users i e those from other universities industry national and government labs are given a handbook for the instrument that t
12. ill be made available for any other qualified user 5 User Levels There are four levels of user for each particular microscope and they may be defined as follows 1 Unrestricted use includes days nights weekends and holidays 2 Use restricted to times when a more qualified user is present in the microscope suite to deal with questions and problems 3 Use restricted to times when a more qualified user is present in the microscope room 4 Non users who require electron microscope studies should negotiate with a qualified user to perform the microscopy 6 Users may be qualified by John Mansfield 936 3352 ESEM FEG SEM 2000 4000 AFM and Corinna Wauchope 936 3353 FEG SEM 2000 4000 AFM XPS Auger ONLY 7 Problems with booking the microscopes should be reported to John Mansfield or Corinna Wauchope NOTE Users will be expected to be competent enough to operate the microscope without having to refer to the user handbook or manuals before they will be allowed unrestricted use date updated May 2000 8 4a amp Radiation Safety Instructions for The North Campus Electron Microbeam Analysis Laboratory University of Michigan Space Research Building 2455 Hayward Ann Arbor MI 48109 2143 By Alan Jackson MS Radiation Safety Service Occupational Safety and Environmental Health 936 1587 date updated May 2000 PROCEDURAL UNIVERSITY OF MICHIGAN USERS Internal university users should receive this notice when t
13. just X Y Z Rotation and tilt if necessary Close the chamber door WATCH your sample does not hit anything on the way in Be especially careful if it is tilted Hold the door closed and click on the PUMP button When you hear the vacuum turn on you can let the door go Wait for the vacuum status message Vac OK before proceeding date updated May 2000 2 GETTING AN IMAGE OF THE SPECIMEN Make sure you wait for the vacuum status message Vac OK before proceeding Choose SE detector Secondary electron detector Pre check Several items should be checked so as to ensure correct operation especially for new users of the XL microscope The following provides a guideline to users kV Accelerating Voltage Low kV for non conductors High kV for conductors Spot Size 3 Scan TV rate Filter Live or Average 4 Magnification Lowest 24x Brightness Contrast Set to 48 and 24 respectivel Turn on the beam after Vac OK On the right side of the screen there should be a small window with Beam at the top Inside will be a HT button that is labeled with the current voltage e g I5kV Click on this gray button to turn on the beam An image will appear after a few seconds possibly out of focus and with incorrect contrast and brightness settings Calibrate the stage A window will appear with the message Confirm the specimen is in focus and click OK to link Z height to FWD free working dist
14. ork efficiently Distance Maximize distance from sources The radiation dose rate is reduced by the inverse square of the distance from the source When you double the distance that you are standing from the machine your radiation dose goes down by a factor of 4 Shielding Modern electron microscopes are well shielded This Engineered control is probably the most important radiation safety feature of modern machines Dose limits Many radiation effects acute Nonstochastic are eliminated if these dose limits are observed Whole Body 5 rem per year Extremity 50 rem per year Skin 50 rem per year Eye 15 rem per year Member of Public 100 mrem per year Minor 500 mrem per year Declared Pregnant Women 500 mrem per pregnancy date updated May 2000 12 ALARA Policy notifications at 10 and 30 of limits Safety Systems Electron Microscopes have a number of safety feature designed to minimize radiation doses For example the sample chamber is typically interlocked with the beam on light This protects the filament and the user Another important safety system is the warning lights These warn you when the machine is operating Beam alignment is an important safety feature Safety systems must be in perfect condition to operate the unit Notify the facility supervisor this system malfunction Surveys Surveying the machine after significant alterations is an important safety technique Radiation Safety Service will survey equipment when re
15. quested The manufacturer repairman should also be able to competently survey the machine after significant maintenance Knowledge You need to fully understand your system if you expect good results and safe operation Reading the manual for the unit and general texts about EM techniques are important means of eliminating safety and experimental problems Personnel Monitoring Techniques Requirement if you will receive 10 of dose limits you must wear a radiation dosimeter no one here is required to be badged If you insist a radiation dosimeter will be issued Note Each machine has a badge These machine badges typically never receive a measurable dose Wearing wear with badge facing outward rings toward source Storing Store in low background area away from extreme heat You have a right to review the results You must be informed if you receive an overexposure NATURAL BACKGROUND RADIATION EXPOSURES This is a highly variable value Total 200 300 mrem per year Radon 150 mrem per year EMPLOYER RESPONSIBILITIES An employer must provide dosimetry train employees provide postings notify employee of overexposures provide procedures WORKERS RIGHTS e Read the Notice to Employees in your laboratory summary e You have the right to contact MDPH e You can not be discriminated against for calling regulators date updated May 2000 13 WORKER RESPONSIBILITIES Abide by all of the rules Keep all the req
16. rols at the right of the screen Maximize the beam window Find the checkbox labeled lens modulator and tick the box The image will appear to go in and out of focus and will shift if the aperture is not centered Center the aperture using the x and y knobs in turn to minimize the movement of the image Uncheck the box to turn off the lens modulator and minimize the beam window e Astigmatism Correction shift right mouse button Astigmatism usually needs to be corrected initially for most specimens and then again after changing kV spot size or working distance The astigmatism in the image is usually only visible at higher magnifications as a guide 3000x or greater Focus as well as possible at the focus magnification Now move the focus control through focus to the other side of focus to observe any astigmatic distortion If astigmatism is present the result observed is a directional distortion change of 90 between the two out of focus conditions To correct the astigmatism hold the shift key and use the right mouse button or select the 2 dimensional Stigmator box in the Image Control Area Clicking anywhere in this box and holding the left hand mouse button in will display cross hairs over the image By moving the cross hairs over the image the image will improve in focus and sharpness at one point It is easier to do one direction at a time If the astigmatism is severe and the cross hairs are close to the edge of the scre
17. s needed e g slow scan 3 and freeze or integrate 1 at photo scan speed e Photograph The camera should be loaded with film and the correct exposure parameters selected These can be found by selecting the menu item Change under the In Out menu There is a choice of five film types with user selectable values of contrast and brightness Once a selection has been made these values are used by default until changed by entering new values or by selection of a new film type The image must be properly focused and stigmated before proceeding e Save File Click on Image under the In Out menu A list box will appear showing the drives and directories available You should save your files on the E drive in the userdata directory Create a directory under your own name YOU MUST COPY YOUR FILES AND STORE THEM ELSEWHERE Files will be deleted periodically without warning from the hard disk You may copy files to a zip disk PC format or you can ftp them from the computer to your AFS space Choose standard or high definition image under the Filter menu Save files as img microscope specific format or tiff standard graphics TIFF format Unfortunately Philips chose to use rectangular pixels in their images and most graphics programs expect square pixels You will need to resize your TIFF images to the correct aspect ratio to correct the resulting distortion Standard Definition 344kB TIFF 702 x 484 pixels High Definition 1 45
18. uired records Do not falsify any record or willfully violate the rules Use Protective Techniques Time Distance Shielding and Decay Report violations of MDPH rules licenses or registration certificates Report unnecessary exposure of radiation to MDPH CONTAMINATION VERSUS EXPOSURE radioactive dirt SURVEYS Survey results X RAY PRODUCTION Bremmstrahlung OPERATING INSTRUCTIONS OPERATOR MUST be authorized by radiation safety supervisor be trained to use the unit notify Radiation Protection Supervisor of any machine malfunctions alterations safety issues read understand follow procedure for unit never insert any part of your body into the unit never repair unit without authorization never alter any interlock for the unit never compromise the shielding of the unit maintain maximum possible distance from the unit during use limit your time near the unit read the notice to employees Radiation producing machines are labeled Interlocks must function at all times Surveys are performed by a Health Physicist Radiation Safety Supervisor John Mansfield EMERGENCY PROCEDURES Administer lifesaving first aid without regard to radiation date updated May 2000 14
Download Pdf Manuals
Related Search