Ionization of ammonia and deuterated ammonia by electron impact from threshold up to 180 eV

Journal Article · Sat Oct 15 04:00:00 EDT 1977 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.435321· OSTI ID:7208469

Maerk, T D; Egger, F; Cheret, M

Electron impact ionization has been studied in NH/sub 3/ and in a mixture of NH/sub 3/ and ND/sub 3/ as a function of electron energy up to 180 eV with a double focusing mass spectrometer. Absolute partial ionization cross section functions have been obtained in NH/sub 3/ for the production of NH/sup +//sub 3/, NH/sup +//sub 2/, NH/sup +/, N/sup +/, H/sup +//sub 2/, H/sup +/, and NH/sup + +//sub 3/ by normalization against the Ar ionization cross section. The ions NH/sup + +//sub 2/ and N/sup + +/, produced by the process NH/sub 3/+e, have been found for the first time, and an estimate of the ionization cross section is given. From the measured partial ionization cross section functions the total ionization cross section function of NH/sub 3/ has been deduced. In addition, it has been possible to measure the ratio of the partial cross section for double and single ionization of the parent ions ND/sub 2/H and ND/sub 3/ as a function of electron energy. The ionization cross section results obtained are compared with previous determinations where available and with a recent semiempirical total ionization cross section calculation by Jain and Khare. Using nth root extrapolation the following ionization and appearance potentials have been derived fom the low energy cross section function: I.P. (NH/sup +//sub 3//NH/sub 3/) =10.4 +- 0.1 eV; A.P. (NH/sup +//sub 2//NH/sub 3/) =16.5 +- 0.2 eV; A.P. (NH/sup +//NH/sub 3/) =22.9 +- 0.5 and 27.2 +- 0.5 eV; A.P. (N/sup +//NH/sub 3/) =29.5 +- 0.5 eV; A.P. (H/sup +//sub 2//NH/sub 3/) =14.8 +- 0.2 eV; A.P. (H/sup +//NH/sub 3/) =23.0 +- 0.2, 27.7 +- 0.5, and 30.6 +- 0.5 eV; I.P. (ND/sub 2/H/sup +//ND/sub 2/H) =10.5 +- 0.1 eV; I.P. (ND/sup +//sub 3//ND/sub 3/) =10.7 +- 0.1 eV; I.P. (NH/sup + +//sub 3//NH/sub 3/) =34.4 +- 0.2 eV; I.P. (NDH/sup + +//sub 2//NDH/sub 2/) = 34.6 +- 1.0 eV; I.P. (ND/sub 2/H/sup + +//ND/sub 2/H) =34.6 +- 0.5 eV; and I.P. (ND/sup + +//sub 3//ND/sub 3/) =34.6 +- 0.5 eV. For the doubly ionized parent molecules a square law has been found from threshold up to some 20 eV above onset. The ionization and appearance potentials obtained are also compared with such earlier results as are available.

• Research Organization: Institut fuer Atomphysik der Universitaet Innsbruck, A 6020 Innsbruck, Austria
• OSTI ID: 7208469
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 67:8; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AMMONIA
COLLISIONS
CROSS SECTIONS
DEUTERIUM COMPOUNDS
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION
MOLECULE COLLISIONS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES