Process and device for measuring ions
The invention relates to a method and a device for the measurement of ions by coupling different measurement methods/techniques, a first detector being a collector ( 17 ) and a second detector being an SEM ( 18 ), and the ions to be measured or resulting secondary particles being selectively delivered to the collector or the SEM. The SEM ( 18 ) is operated selectively in analog mode or count mode. The collector ( 17 ) is provided with an integrator.
1. A method for the measurement of ions coming from an analyzer ( 11 ) by coupling different measurement methods/techniques, a first detector being a collector ( 17 ) and a second detector being an SEM ( 18 ), comprising the steps of:
selectively deflecting the ions to be measured and coming from the analyzer ( 11 ) to the collector or to the SEM after conversion to secondary particles,
selectively operating the SEM ( 18 ) in analog mode or pulse counting mode, and automatically switching between the first and second detectors and the associated measurement ranges for carrying out measurements over a wide dynamic range.
2. The method as claimed in claim 1 , wherein the collector ( 17 ) is operated with an integrator.
3. The method as claimed in claim 1 , wherein for measurement using the SEM ( 18 ), the ions first generate the secondary particles and then the secondary particles travel to the SEM.
4. The method as claimed in claim 1 , wherein the measurement ranges of the collector ( 17 ) and of the SEM ( 18 ) overlap each other.
5. The method as claimed in claim 1 , wherein the measurement ranges of the count mode and the analog mode overlap each other.
6. The method as claimed in claim 4 , wherein the different measurement ranges are calibrated with respect to one another during or before the measurement.
7. The method as claimed in claim 6 , wherein the calibration is carried out by measuring the same ion mass for all measurement ranges and by matching the results.
8. The method as claimed in claim 1 , wherein the ions to be measured are separated beforehand in the analyzer, which is a component of a mass spectrometer.
9. A device for the measurement of ions, comprising:
an analyzer ( 11 ),
a collector ( 17 ) as a first detector and an SEM ( 18 ) as a second detector, wherein the SEM ( 18 ) has at least two terminals ( 19 , 20 ) or signal outputs, namely at least a terminal ( 19 ) for an analog mode and a terminal ( 20 ) for a pulse counting mode,
a steering unit ( 14 ) (deflector) for selectively steering the ions coming from the analyzer ( 11 ) deflecting to the collector or to the SEM after conversion to secondary particles, and
a unit ( 21 ) for switching between a signal output of the collector ( 17 ) and the terminals ( 19 , 20 ) of the SEM ( 18 ).
10. The device as claimed in claim 9 , wherein the SEM ( 18 ) is preceded by a conversion dynode ( 15 ) so that only electrons enter the SEM.
11. The device as claimed in claim 9 , wherein the steering unit ( 14 ) is arranged and aligned so that the ions travel to the collector ( 17 ) in a setting in which there is no deflection or only minor deflection, and the ions or resulting secondary particles travel to the SEM ( 18 ) in a setting in which deflection takes place.
12. The device as claimed in claim 9 , wherein the steering unit ( 14 ) contains a conversion dynode ( 15 ) so that the particles travelling from the steering unit to the SEM ( 18 ) are (secondary) electrons.
13. The device as claimed in claim 12 , wherein the steering unit ( 14 ) contains a deflector electrode ( 16 ) arranged between the conversion dynode ( 15 ) and the SEM ( 18 ), and which has at least one passage for the electrons.
14. The device as claimed in claim 9 , wherein the collector ( 17 ) is provided with an integrator for integrating the signal obtained from the collector.
15. The device as claimed in claim 9 , having a unit ( 21 ) for calibrating the results of the measurement using the collector ( 17 ) with respect to the measurement by the SEM ( 18 ) in analog mode, and for calibrating the results of the measurement by the SEM in analog mode and the SEM in pulse counting mode.
16. The method as claimed in claim 5 , wherein the different measurement ranges are calibrated with respect to each other during or before the measurement.
17. The method as claimed in claim 16 , wherein the calibration is carried out by measuring the same ion mass for all measurement ranges and by matching the results.
18. The method as claimed in claim 1 , wherein the measurement ranges of the collector ( 17 ) and of the SEM ( 18 ) overlap each other by at least two orders of magnitude.
19. The method as claimed in claim 1 , whereIn the measurement ranges of the pulse counting mode and the analog mode overlap each other by at least two orders of magnitude.
20. The method as claimed in claim 1 , wherein:
the step of automatically switching between the first and second detectors comprises automatic switching between the collector ( 17 ) on one hand and both terminals ( 19 , 20 ) of the SEM ( 18 ) on the other hand for carrying out measurements over a wide dynamic range, and
further comprising the step of automatically switching off the pulse counting mode beyond a threshold of signal output so that the analog mode only is continuing to be used.
21. The device as claimed in claim 9 , wherein
the unit ( 21 ) switches between the collector ( 17 ) on one hand and both terminals ( 19 , 20 ) of the SEM ( 18 ) on the other hand, and
the unit ( 21 ) automatically switches off the pulse counting mode beyond a threshold of signal output so that the analog mode only is continuing to be used.