Electron ionization study of ammonia micro-clusters
An electron impact ion source on a double focusing sector field mass spectrometer was used to investigate ammonia micro-clusters produced by the adiabatic free jet expansion of ammonia gas. The appearance energies for [NH(3)](n)(+), n </= 9, ions have been determined. Results of measurements of appearance pressures of selected clusters are described for a range of operating conditions. An empirical formula describing the ammonia clusters production is proposed. Copyright 2000 John Wiley & Sons, Ltd.
Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
A
Pelc
L
Michalak