| 摘要 |
The invention relates to determining the masses from the time-of-flight values of ions in time-of-flight mass spectrometers where the accelerating voltage for the ions is not applied permanently, but is switched on at a certain time, resulting in a temporally changing acceleration for a short time after the voltage has been switched on. An aspect of the invention includes formally describing the effect of the temporally changing acceleration on the calibration curve-an effect which cannot be subjected to a strict mathematical-analytical calculation-by introducing a "reduced mass" m-m0 instead of the mass m. The mass reduction factor m0 does not describe a real mass difference, but a mass-dependent shortfall in the final kinetic energy after the ions have passed through the acceleration, a shortfall which can be observed with the temporally changing acceleration. This surprisingly simple formalism makes it possible to calculate the mass of the ions over a wide mass range and with an accuracy of approximately one part per million of the mass, using a calibration curve containing only four to six calibrated coefficients.
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