A New Method to Study the Kinetics of Ion Decay in a Radio Frequency Quadrupole with Resonance Rotational Excitation

A new method to study the kinetics of ion decay reactions in a radio frequency quadrupole (RFQ) with resonance rotational excitation is described. The decay reaction occurs while ions move through the RFQ and the resulting precursor-ion consumption, as well as the appearance of fragment ions, are monitored using high-resolution orthogonal time-of-flight mass spectrometry (o-ToF MS). The developed method enables one to extract absolute values of the decay rate constants using the ion drift motion under the uniform DC electrical field along the RFQ created by the segmented structure. The ion dwell time, as well as its internal temperature are calculated using the ion mobility measured under the same experimental conditions as the kinetic investigations. The values of the decay rate constants, activation energies and preexponential factors for three substances under investigation are reported.