Fragmentation probability in collisional-activation mass spectrometry (Ca/MS). II. Effect of daughter-ion cross-section

Probability theory is used to describe the effect of the cross-sections for collisional ion-loss of daughter ions on fragmentation yield in collisional-activation mass spectrometry (CA/MS). Expressions for the parent-ion and total daughter-ion intensities are derived using the usual two-step model for the collisional-activation (CA) process and also for the more general sequential excitation model proposed previously. A smaller cross-section for the loss of daughter ions by collision as compared to that of the parent is found to affect the experimental CA data (daughter vs. parent intensities) in a similar way to sequential excitation. Independent determination of relative ion-loss cross-sections for daughter ions seems to be needed to obtain information concerning the dynamics and energetics of a CA process from CA experiments.