Manual for the residual gas analyzer
("Pfeiffer QMS 200 F2")

Key fragment ions

• Switch off the vacuum pump and wait until its rotation frequency is nearly 0.

   

• Allow nitrogen gas into the probe chamber, until its pressure is similar to that outside the chamber. Open the chamber and put your probe onto the probe holder in a way which ensures optimal heat conduction. Close the chamber immediately and restart the turbo-molecular pump.

   

• In the   Service   subprogram click on   Measure: Total Pressure. A display will show the pressure inside versus time. If the pressure is below 10^-4 mbar the residual gas analyzer can be started. To do this, start the   Measurement   subprogram and click on   Setup: SEM/Emission Control. In the small window which appears switch the emission on. The heating symbol will change to yellow.

Start the program   Measurement. Spectral scans can be plotted as a histogram ("bargraph") or as a continuous curve ("analog").

• For a bargrapg spectrum select   Scan: Bargraph. You will be prompted for a parameter file which describes the time and range of the scan. To make a scan for the atomic masses 0 to 200 amu, lasting 1 second per amu, select the file "scbf.sbp". We used this as default. Additional parameter files can be created.

   

• In order to make an analog scan of the probe click on   Scan: Analog. As a default parameter file we used "scaf.sap".

Start a bargraph or analog scan as explained above.

• To save the next cycles select   File: Save cycle data   and give a name to the file with not more than eight letters (DOS standard), click "Ok". In the small window which will appear enter the number of cycles to be saved (usually one cycle). After that, in another window you may enter additional informations (time, temperature, pressure, probe data) to be saved together with the spectrum.

   

• If you need to subtract one spectrum from another (see below), you can save it right at the beginning as a reference spectrum. To do this select   File: Save reference   and proceed as explained above. Analog data can be converted between cycled data and references. This is not possible for bargraph scans, where you need to know in advance what you are going to subtract from what.

Saved spectra can be viewed in the subprogram   Dispsav. Select   Scan: Analog Data   or   Scan: Bargraph Cycles   respectively.

• Analog spectra can be converted to ASCII data or processed with a graphic editor. Annotations as well as a three dimensional view of several cycles are possible.

   

• These features are not available for bargraph cycles. However this data format is more important in our case.

By selecting   File: Print   in the subprogram   Dispsav   the current spectrum will be printed as an ASCII table only.

• Press simultaneously "Ctrl" + "Shift" + "F12" and a prompting window will occur: You can print the currently active window or the whole screen to the standard printer or to a bmp-file. Shrinking or magnification of the output is also possible.

   

• A screen capture can be copied via the WINDOWS clipboard into other applications. Press the button "Print Screen" for a copy of the entire screen or "Alt" + "Print Screen" to copy only the active window. You can paste this with "Shift" + "Insert" into another program.

• The software contains a spectra library for 63 chemical substances. Various spectra of the probes could be appended and therein overlayed to other spectra or subtracted. However, these spectra must not possess more than 32 lines, otherwise some peaks will be cancelled.

   

• In order to subtract a spectrum stored as a reference (see above) from a spectrum which is currently saved, select the reference with   File: Load reference. Click on   Scan: Setup   and choose in the window which will appear "Save data as difference". You can also select which spectra (current, reference, difference) will be displayed, but only the difference will be saved. Don't forget to reset to "Save data as current" if you want to store a spectrum as it is.

   

• Analog data can be converted to ASCII and processed with other programs. When importing these into EXCEL, the exponents' values will be falsified. To solve this problem go to the WINDOWS "Control Panel" - "Regional Settings" - "Number Format" and enter as "Digit Grouping Symbol" (the 1000-separator) a quotation mark (').