How does the molecular velocity distribution affect kinetics measurements by time‐resolved mass spectrometry?

The equations governing the time fidelity in molecular‐beam mass sampling are derived for supersonic‐beam sampling, where the velocity distribution is well‐fitted by a displaced Maxwell–Boltzmann distribution. Supersonic sampling is shown to offer much higher fidelity than the corresponding effusive‐beam sampling, and rules of thumb are derived for the validity of kinetic measurements for supersonic‐beam sampling.