Ion Dipole Capture Cross Sections at Low Ion and Rotational Energies; Comparison of Integrated Capture Cross Sections with Reaction Cross Sections for NH3 and H2O Parent-Ion Collisions

Numerical capture cross sections calculated for CH3CN++CH3CN collisions for a rotational temperature TR of 77°K are in the range 1000–3500 Å2. Comparisons of capture cross sections (integrated over experimental ion energies) for H2O and NH3 at TR ≈ 300°K are in mixed agreement with experimental data from (1) a conventional mass spectrometer and (2) an ion cyclotron resonance device.