Quadera Pfeiffer программа управления (1248465), страница 14
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You will return to the measurementproject without saving the data.121QUADERA HTML HelpOffset ParametersThe calibration project displays the parameters required to determine the offset.Modified parameters are forwarded to the device and take effect in the nextmeasurement task.Offset parameters QMG220ParameterRangeDescription•(not editable)Offset value for the correspondingmeasuring range of the detector.E-05…E-12The device automatically determinesthe values listed in the correspondingtable.See also recipe parameter "AmplifierRange".•Offset Mass0 <= value <=MaxRangeMass for the offset measurement.•DeleteOffsetEntriesButtonDeletes the offset values for thedetector.Offset parameters QMG700ParameterRangeDescription•(not editable)Offset value for the correspondingmeasuring range of the selecteddetector.E-05…E-12The device automatically determinesthe values listed in the correspondingtable.See also recipe parameter "AmplifierRange".•ElectrometerPreamplifierDropdown listDetector type for the offsetdetermination.•Faraday,•SEM•Offset Mass0 <= value <=MaxRangeMass for the offset measurement.•DeleteOffsetEntriesButtonDeletes the offset values for thedetector that is selected in"Electrometer Preamplifier".122QUADERATuning the RF GeneratorTuning the RF GeneratorBasicsThe high frequency voltage of the RF generator (QMH, or RF22x for QMG220, seedevice settings) is applied to the rod pairs of the QMG to separate ions.
The outputresonant circuit of the generator has to be matched to the QMG rod system in thefollowing cases:•when commissioning the device,•problems appear when masses near the upper mass scale limit are measured.ProcedureTuning the RF generator requires to turn the tuning screw.
The calibration project inQUADERA® is used to display and check the tuning voltage.NOTE:Use the device specific instructions (OEM manual) when tuning the RFgenerator.•Tuning the RF generator for the QMG220,•Tuning the RF generator for the QMG700.123QUADERA HTML HelpMinimizing the Tuning Voltage (QMG220)This topic applies to the QMG220.NOTE:Use the device specific instructions (OEM manual) when tuning the RFgenerator.1. Open the start page: In the View menu, click Show Start Page.2. Click on the icon for the required device.3.
Create a new calibration project: In the "Calibration and Tuning" list, doubleclick RF Tuning.qmt. This way you create a new calibration project based onthe selected template.4. The new measurement project window appears. The working area displays thecalibration project. Note:• No recipe is assigned to this calibration project. Thus, no user specificadaptation is available.• An actual measurement is not performed, i.e. you can not start and stopthe measurement.5. Proceed as follows to tune the output resonant circuit of the generator:• Observe the signal bar in the working area. It displays the actualgenerator tuning voltage.
The two drag indicators show themaximum and minimum achieved voltage.• Use the Reset Arrows command of the context menu "Chart" toreset the two drag indicators.• Adjust the tuning screw of the generator to minimize the tuningvoltage. Refer to the OEM manual. The tuning voltage should notexceed half of the maximum signal.NOTE:Do not damage the tuning screw of the generator. Never tighten or removethe tuning screw.6.
Close and save the measurement project. In the File menu, click Close. Youare requested if you want to save the measurement project. QUADERA®suggests an automatically generated file name that is based on date/time ofthe measurement and the used template.• Yes: the "Save As" window used for saving measuring data opensup. Select a suitable name and path and then click Save. Themeasurement project will be saved and closed.Please note: The file extension for measurement projects is *.qmp• No (recommended option): the measurement project will be closedwithout saving the data.• Cancel: the action is cancelled. You will return to the measurementproject without saving the data.124QUADERAExtended context menu "Chart"In the calibration project "RF Tuning" the context menu "Chart"provides an additional command:•Reset ArrowsReset the drag indicators that show themaximum and minimum achieved tuningvoltage.125QUADERA HTML HelpMinimizing the Tuning Voltage (QMG700)This topic applies to the QMG700.NOTE:Use the device specific instructions (OEM manual) when tuning the RFgenerator.1.
Open the start page: In the View menu, click Show Start Page.2. Click on the icon for the required device.3. Create a new calibration project: In the "Calibration and Tuning" list, doubleclick RF Tuning.qmt. This way you create a new calibration project based onthe selected template.4. The new measurement project window appears. The working area displays thecalibration project. Note:• No recipe is assigned to this calibration project. Thus, no user specificadaptation is available.• An actual measurement is not performed, i.e. you can not start and stopthe measurement.5.
The QMH is set to the maximum mass number. Tune the output resonantcircuit as described in the instructions of the RF generator.NOTE:Do not damage the tuning screw of the generator. Never tighten or removethe tuning screw.6. Close and save the measurement project. In the File menu, click Close. Youare requested if you want to save the measurement project. QUADERA®suggests an automatically generated file name that is based on date/time ofthe measurement and the used template.• Yes: the "Save As" window used for saving measuring data opensup.
Select a suitable name and path and then click Save. Themeasurement project will be saved and closed.Please note: The file extension for measurement projects is *.qmp• No (recommended option): the measurement project will be closedwithout saving the data.• Cancel: the action is cancelled. You will return to the measurementproject without saving the data.126QUADERABackground DeterminationBackground DeterminationBasicsThe so-called mass spectrometer background is caused by residual gases. Thesegases are present in every analysis chamber and do not originate from the measuringsample.
The background is mainly constant if the measuring apparatus is wellconditioned. However, measurement results may be distorted if the background is notconsidered properly. The background determination identifies the existing residualgases. The detected ion currents are subtracted from subsequent measurementprojects. The result will show the true composition of the measuring gas.ProcedureResidual gases are measured either with the gas inlet closed or by using a zero gas,i.e. a pure gas that is fed into the analysis chamber to reach the same pressure asexpected for future measurements. Using a zero gas takes account of adsorption anddesorption effects better than pumping down the chamber to final vacuum.An MID measurement is used to determine the background.
The recipe parametersare defined in the corresponding calibration project. Use the recipe editor to changethe parameters. You can determine the mass spectrometer background for eachdetector type separately and store the results in the Background Library. Thestored values will be used in future MID and MCD measurement projects where theyare subtracted from the measured signals.NOTE:Always pump down the chamber to final vacuum before performing thebackground determination, or let in a suitable zero gas.
Otherwise, seriousmeasurement errors may result.127QUADERA HTML HelpMeasuring the BackgroundNOTE:Before starting the measurement, check the correct calibration of the of themass spectrometer components. If a calibration is necessary, perform thefollowing preparatory measurements:• Calibrate the mass scale,• Determine the offset.1. Feed a suitable zero gas into the vacuum chamber, or pump the chamberdown to final vacuum.2. Open the start page: In the View menu, click Show Start Page.3. Click on the icon for the required device.4.
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