Tomasz Wróblewski

Influence of resonant scattering on electron-swarm parameters in NO

Abstract A semiempirical analysis of low-energy electron scattering in nitric oxide has been performed. The deduced set of total and partial cross-sections has been used to calculate the ratio of electron transversal diffusion to mobility at low and intermediate reduced electric fields. The modelling gives indications for high values of vibrational cross-section in the 0.7–1.2 eV energy range that can be explained assuming presence of two resonant states, the first one similar to the low-energy 2 Π g resonance in O2, the second one resembling the 2 Π g resonant state in N2.

Swarm experiment on ionized water clusters

Drift of positively ionized water clusters formed in a low-pressure electrical discharge was studied by mass spectroscopy. Ions H 1 (H2O)n with n 5 1‐7 were observed at room temperature and at pressures in a few hundreds Pa range. Relative cluster abundances depend on the reduced electrical field in the drift chamber. The H 1 (H2O)4 clusters are somewhat more abundant than those with n 5 3, 5. Fragmentation energies, in a rough agreement with other experimental and theoretical values, have been derived from equilibrium conditions for relative cluster abundances. Calculations of dissociation energies of cationic clusters with n up to 7 have been performed in Hartree-Fock approximation with a 6-311**G basis set. (Int J Mass Spectrom 207 (2001) 97‐110)

Proton transfer reactions for ionized water clusters

Calculations of formation energies of the ionized water clusters and energies of reactions between small (including less than eight water molecules) neutral and positively ionized water chisters are presented. Moreover, we discuss some reaction paths between neutral and positively charged dimers, trimers and tetramers and proton transfer reactions (PTR) between cyclic clusters and H3O+ ions which can appear in beam, experiments on formation and ionization of water clusters. Calculations were made using ab initio Hartree-Fock method for 4–31G and 6–311G** atomic orbitals basis sets.

Dissociation energies of protonated water clusters

Abstract Relative abundances of positively ionized water clusters formed in a low-pressure electrical discharge as function of reduced electric field were obtained by using drift cell and quadrupole mass spectrometer. It was noticed that some clusters say with n=4 were more abundant than others, at comparable drift conditions. Dissociation energies have been derived from equilibrium conditions for relative clusters abundances. The Hartree–Fock method in 6-311G** molecular-basis set has been applied to calculations of binding energies for different structural “families” of clusters.

Low-energy electron collisions in nitrogen oxides: a comparative study

Cross-sections for low-energy electron scattering in nitric oxide (NO), nitrous oxide (N 2O) and nitrogen dioxide (NO2) are discussed. We compare earlier and recent cross-sections derived from beam and swarm experiments for elastic, vibrational, electronic excitation, ionization, electron attachment phenomena. The importance of resonant scattering at low energies is stressed for all three targets. (Int J Mass Spectrom 223–224 (2003) 205–215)

Electron scattering on N2O-from cross sections to diffusion coefficients

Abstract Results of measurements of the ratio of transverse ( D T / μ ) and longitudinal ( D L / μ ) diffusion coefficients to mobility and drift velocity ( W ) as function of reduced electrical field ( E / N ) for electrons in nitrous oxide are presented. The coefficients D T / μ and D L / μ have been determined by applying the Townsend–Huxley method. The drift velocities were obtained by using the Bradbury–Nielsen technique. Also the deduced set of total and partial cross sections has been used to calculate the D T / μ and W .

Electron Scattering on Triatomic Molecules: The Need for Data

We review data sources for electron–molecule scattering cross sections, paying particular attention to triatomic molecules, such as CO2, N2O, and OCS. Experimental cross sections obtained by beam techniques are compared with those obtained by swarm-data modeling. The need for measurements of inelastic processes, particularly electronic excitation and dissociation, is stressed.

Semiempirical analysis of electron scattering cross sections in N2O and CO2

Results of swarm analysis of electron scattering cross sections in nitrous oxide and carbon dioxide are presented — experimental diffusion coefficients are compared with numerical solution of the Boltzmann equation. Total cross sections for both N2O and CO2 exhibit similar resonant, structure and diffusion and drift coefficients are also similar. However, our analysis shows that values of partial cross sections, in particular vibrational ones (important for greenhouse IR absorption) can be quite different for those gases at low energies — much higher that commonly used now.

Proton affinity and proton transfer energy for selected organic molecules

The Hartree-Fock method in 6-311G** molecular orbitals basis set has been applied to calculations of proton affinities and proton transfer reaction energies for water methanol acetaldehyde ethanol acetone acetic acid methyl acetate and ethyl acetate.

Electron-diffusion coefficients in N2O

Results of measurements of the ratio of transverse (DT/μ) and longitudinal (DL/μ) diffusion coefficients to mobility and drift velocity (W) as function of reduced electrical field (E/N) for electrons in nitrous oxide are presented. The coefficients DT/μ and DL/μ have been determined by applying the Townsend-Huxley method. The drift velocities were obtained by using the Bradbury-Nielsen technique. A set of total and partial cross sections has been used to calculate numerically the DT/μ and W.