Basic Procedures

Some basic procedures in operating the CM2000FEG TEM are presented here. For more edvanced procedures such as alignment and cryo EM please refer to Philips Operation Instruction for CM200 (Doc#: PW6061), a copy of which is on the book shelve in the CM200 EM room.

Start-up the Scope

1. Turn on the water and pneumatic supplies to the microscope.
   
2. Switch on the electrical supply to the microscope. The MICROSCOPE STANDBY button will illuminate.
   
3. Press the MICROSCOPE ON button. The rotary vacuum pump sill start up. The MICROSCOPE OFF button will illuminate red, indicating its emergency function (this is active when the instrument is in operation.
   
4. Press VACUUM ON push button (VACUUM OFF LED illuminate). The microscope will now be pumped down automatically until the operational vacuum is reached (after 20 - 30 min.).
   
5. Check the Dewar vessel of the Cooling Device. If necessary, remove the vessel, refill with liquid nitrogen and then replace.
   
6. Once UHV indicator is illuminated, operational vacuum has been reached.

Continuous Pumping

The microscope should be pumped continuously in order to improve the quality of the vacuum and thereby reduce specimen contamination. There are two options:
Leave-it-on: Simply leave it on.
Standby: Swith HT off and press STANDBY button.
In the standby condition, the ion getter pump continuously pumps the microscope column, but the camera airlock valve is closed, the oil diffusion pump valve is closed, all electronics except those for the ion getter pump are switched off, and the cooling water stops flowing through the lens coils.

Download Lens Currents

This is only necessary when the microscope fails on some software tests (when it shows messages such as "program block X test failed").

1. Turn on the AcerPower computer (which is usually kept on) to the left of the microscope.
   
2. Go to Windows Program Manager and click Downloadable Lens Series Group.
   
3. Selet File button.
   
4. Select CM112b.EXE.
   
5. Note the message on display monitor of the microscope "waiting for PC to attach".
   
6. Select Download as soon as the message appears. Then the display monitor of the microscope will show "Downloading (xx%)". Wait until it is finished approxmately 70% (about 15 minutes). Then it will continue checking all program blocks untill all are ok.
   
7. Select Start CM. The scope normal start-up sequence will begin with CompuStage calibration and vacuum checking.
   

Cold/Warm Start

1. Make sure Gun Valve switch (on the counter between the display monitor and the column of the scope) is in CLOSED position.
   
2. Switch Microscope Power ON if it is not ON.
   
3. Remove Specimen Holder (if requested)
   
4. Switch on IGP2 supply at the back coner of the CM200 room below the main power breaker box (if ON indicator lamp is not lit)
   (a) Set START switch to START position
   (b) Set POWER switch from OFF to ON position
   (c) Make sure meter indication is above zero level (on lowest scale)
   (d) Reset START switch to normal position
   
5. Wait for the microscope to finish vacuum cycle and the message "Please Initialize FEG" to display.
   
6. Press INITIALIZE on Configuration FEG control page (check that FEG state goes to "IGP TIP ON") if FEG error message displays, and initialization is not achieved, try following:
   (a) Reset FEG POWER softkey and try to initialize
   (b) Reset CTB board and try to initialize
   (c) Remove and insert 24V power supply (filament supply in Power Rack)
   
7. Select FEG "DISPLAY" page
   (a) If IGP3 reading is greater than 0.100 then go to step 9; otherwise go to step 8.
   
8. When IGP3 is less than 0.100 after INITIALIZATION, pump is considered OFF. Then do the following:
   (a) Switch OFF IGP2 (at the bottom of the power rack)
   (b) Wait until IGP3 indication reaches 0.2 or higher (this could be immediate or take over 1/2 hours)
   (c) Restart IGP2 (make sure IGP2 level is above zero on lowest scale)
   (d) Both IGP2 and IGP3 are now operating
   
9. Wait until IGP3 level is below 0.5 microamps and press "COLD START" (if FEG has been OFF longer than 1 hour or not sure how long it has been OFF) or "WARM START" (if FEG is sure to have been OFF shorter than 1 hour). After 90 (COLD START) or 30 (WARM START) minutes, FEG STATE will switch to "OPERATE".

Mount Specimen

This is the procedure to mount a specimen on a Philips single tilt holder, which shows the major steps that are similar to othe more complicated holders.

1. Check that the tip of the holder and the clamping device are clean and dry.
   
2. Rest the holder on its support with the spring clamp horizontal and uppermost, ensuring that the tip is properly supported by the recess in the block.
   
3. Fit the tool (stored in the support) into the hole in the front of the clamp then lift the clamp to its fullest extent.
   
4. Carefuly place the specimen in the carrier.
   
5. Carefully lower the clamp onto the specimen (or grid) using tool. Make sure that the specimen remains correctly in position.
   

Holder Selection
The CompuStage has the socalled "safe entry system" that prevents insertion of non-compatible holders, and extraction of holders under unsafe conditons. The safe entry system consists of a safe entry key, which is a pin projecting from the specimen holder, and the safe entry lock. The safe entry lock is a switch on the CompuStage with an opening in which the safe entry key should fit. If the safe entry key does not fit, it means that this holder is not compatible with the pole pieces of the microscope; and that it is not possible to insert the holder. Two different positons of the switch are possible, i.e., the SELECT and the NON-SELECT positions.

The SELECT position: In the SELECT position the user is obliged to make a choice from a list of holders. The exact dimensions of every holder are stored in the memory of the microscope and are recalled when the holder is identified. In this lab, we use three types of holders, i.e., Philips, Oxford, and Gatan holders. SELECT positon must be chosen for the Oxford and Gatan holders.

The NON-SELECT position: This position may be used for routine work with the standard single tilt holder. In this position the user can insert the holder without holder identification (no holder selection page is visible). Insertion of a holder other than the standard single tilt CompuStage holder is not possible in the NON-SELECTION position. The user is then forced to switch over to the SELECT position and to select the correct holder on the holder selection page.

Insert Specimen Holder:
The holder is inserted through a pre-pumped airlock which ensures that air, introduced with the holder, is pumped away before the airlock is opened to the microscope column.

1. Choose the SELECT or NON-SELECT position on the Safe ENTRY lock of the CompuStage.
   
2. Hold the specimen holder with the airlock-opening pin parallel to the small slit in the goniometer-cap. Carefully insert the end of the specimen holder into the airlock entry and slide it in until a stop is reached. At this point pre-pumping of the airlock commences as indicated by illumination of the red airlock indicator light. The airlock box is mounted to the left of the column facing the user of the scope.
   
3. If the Safe ENTRY lock is in the NON-SELECT position continue with 4. If the Safe ENTRY lock is in the SELECT position the microcontroller display will show the holder selection page. Choose the correct holder (only Gatan and Oxford holders are used in this lab) by pressing the corresponding softkey and confirm with READY. The holder selection page is then removed from the screen.
   
4. Wait until the airlock indicator light is extinguished, rotate the holder about 120 degrees conter-clockwise as far as it will go, then allow it to slide in as far as it will go. Maintain a firm grip on the holder during insertion. It it is allowed to enter the column too quickly, sue to suction by the vacuum, damage to the goniometer movements and holder can occur.
   
5. Carefully tapping the holder with the finger may help to improve the short-term drift.
   

Obtain Image

Move Specimen (Z)

Move Specimen (X,Y)

Tilt Specimen

Focus Image