Cross Sections For Low-energy Electron Collisions Research Articles

Theoretical study of the low-energy electron-collision cross sections of isomers HOOCl, HOClO and HClOO in gas phase

Cross sections for the elastic electron scattering by HOOCl, HOClO and HClOO isomers are calculated using the R-matrix method. A systematic study considering basis set, polarisation and the Born closure technique is performed. Low-energy resonances are found for both HOOCl and HOClO, near 1.7 and 1.2 eV respectively, but not for HClOO. The lowest-energy resonance for HClOO is observed at 4.5 eV. Basis sets and polarisation effects on the differential cross sections are found to be important for scattering energies below 5 eV for HOOCl and HOClO due to the presence of these resonances. The dependence of the molecular dipole moment on target basis set used affects the integral cross sections (ICS) results. The ICS for HOClO is larger than other two isomers due to its larger dipole moment, around 3.2 D, while the ICS for HOOCl and HClOO have similar magnitude as both their dipole moments are near 1.9 D. Estimated dissociative electron attachment (DEA) cross sections suggest that HOOCl and HOClO will undergo DEA with low-energy electrons but that HClOO requires higher-energy electrons to undergo DEA.

Electron Collision Cross Sections for the TRIES Molecule and Electron Transport Coefficients in TRIES-Ar and TRIES-O2 Mixtures

A reliable set of low-energy electron collision cross sections for the triethoxysilane (TRIES) molecule was derived based on the measured electron transport coefficients for a pure TRIES molecule by using an electron swarm method and a two-term approximation of the Boltzmann equation. The electron transport coefficients calculated using the derived set are in good agreement with experimental value over a wide range of E/N values (ratio of the electric field E to the neutral number density N). The present electron collision cross section set for the TRIES molecule, therefore, is the most reliable so far for plasma discharges and for materials processing using the TRIES molecule. Moreover, the electron transport coefficients for the TRIES-Ar and the TRIES-O2 mixtures were also calculated and analyzed over a wide range of E/N for the first time.

Determination of the electron collision cross sections for the C2H4 molecule by using the electron swarm method

A set of low-energy electron-collision cross sections for ethene (C2H4) is necessary for quantitative numerical modeling of plasma discharges for processing procedures with materials containing C2H4 molecules. The set was derived from the measured electron transport coefficients for a pure C2H4 molecule by using an electron swarm study and a two-term approximation to the Boltzmann equation for energy. The electron transport coefficients, which were calculated by using the derived set, are in good agreement with the experimental values over a wide range of E/N ratios in pure C2H4 molecule, where E is the electric field and N is the neutral number density. The validity of the present set of the C2H4 molecule was not only checked by using a Monte Carlo simulation but also evaluated by comparison with another set.

Electron Collision Cross Sections for the BF3Molecule and Electron Transport Coefficients in BF3–Ar and BF3–SiH4Mixtures

A consistent set of low-energy electron collision cross sections for the boron trifluoride (BF3) molecule has been derived from the measured electron transport coefficients for a pure BF3 molecule using an electron swarm study and a two-term approximation of the Boltzmann equation for energy. The electron transport coefficients, which were calculated using the derived set, are consistent with the experimental data over a wide range of \(E/N\) values (ratio of the electric field \(E\) to the neutral number density \(N\)). The present set of electron collision cross sections for the BF3 molecule, therefore, is the best available so far for the quantitative numerical modeling of plasma discharges for processing procedures with materials containing BF3 molecules. The electron-transport coefficients for BF3–Ar and BF3–SiH4 mixtures were also calculated and analyzed in a wide range of \(E/N\) ratios for the first time. The presence of a remarkable synergism in the Townsend first ionization coefficient has been pointed out in BF3–SiH4 mixtures.

Electron collision cross sections for the TMS molecule and electron transport coefficients in TMS-Ar and TMS-O2 mixtures

A consistent set of low-energy electron-collision cross sections for the tetramethylsilane (TMS) molecule has been derived from the measured electron transport coefficients for a pure TMS molecule by using an electron swarm study and a two-term approximation of the Boltzmann equation for energy. The electron transport coefficients, which were calculated by using the derived set, are consistent with the experimental data over a wide range of E/N values (ratio of the electric field E to the neutral number density N). The present set of electron collision cross sections for the TMS molecule, therefore, is the best available so far for quantitative numerical modeling of plasma discharges for processing procedures with materials containing TMS molecules. The electron-transport coefficients in TMS-Ar and TMS-O2 mixtures were also calculated and analyzed in a wide range of E/N ratios for the first time. The presence of a remarkable synergism in the Townsend first ionization coefficient has been pointed out in the TMS-O2 mixtures.

Low-energy electron collision cross sections of sodium

Using R-matrix method, the collision cross sections of sodium from ground state to the first a few excited states at incident energy range 0-5.4 eV are calculated. The influence of the Rydberg states to the collision cross sections is elucidated, which implies the cross sections obtained by partial wave expansion methods at low-energy could be interfaced with the cross sections obtained by first Born approximation methods at high-energy.

Electron collision cross sections for tetraethoxysilane

We describe the development of a consistent set of low-energy electron-collision cross sections for tetraethoxysilane, also known as tetraethylorthosilicate. Ab initio calculations are used to obtain the elastic and momentum-transfer cross sections. These are combined with measured values of the ionization cross section and with model vibrational and electronic excitation cross sections to form a preliminary cross section set, which is then adjusted to achieve consistency with measured swarm parameters.

Electron cross section set for CHF3

We describe the development of a consistent set of low-energy electron collision cross sections for trifluoromethane, CHF3. First-principles calculations are used to obtain key elastic and inelastic cross sections. These are combined with literature values of the ionization cross section and with vibrational excitation cross sections obtained from the Born approximation to form a preliminary set, which is then adjusted to achieve consistency with measured swarm parameters.

Low-energy electron collision cross sections of ethane by electron swarm study

The drift velocity and the longitudinal diffusion coefficient of electrons in 0.206% and 1.98% ethane - argon mixtures and in pure ethane were measured in the E/N ranges 0.03 - 3 Td, 0.03 - 25 Td and 0.03 - 300 Td respectively. The measured swarm parameters in the mixtures were used to determine the essential vibrational excitation cross sections of the ethane molecule and those measured in pure ethane were used to derive the elastic momentum transfer cross section for the molecule in conjunction with the above derived vibrational cross sections. Consideration of realistic anisotropies of the electron scattering had little effect on electron swarm parameters.