Cross sections of the electron impact dissociative ionization of CO, ? and ?
TL;DR: In this paper, the cross sections of the electron impact ionization and dissociative ionization of CO, and have been measured for electron energies from threshold to 600 eV, are presented.
Abstract: The cross sections of the electron impact ionization and dissociative ionization of CO, and have been measured for electron energies from threshold to 600 eV. The present values agree with the previous measurements where a complete collection of the resulting ions has been demonstrated experimentally. However, for the processes where no complete collection has been demonstrated, the present results are usually higher if the ions are produced with higher kinetic energy. The present measurement demonstrates the complete collection of the ions experimentally and the results are thus believed to be reliable. The disagreement between the present results and the previous ones is explained by noting the kinetic energy distributions of the fragment ions.
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TL;DR: An extensive review of the results from literature on electron beam induced deposition is given in this article, where the authors categorize the data according to the specific parameter that can have an effect on the final deposit properties, such as the physical dimensions, the composition, the morphology or the conductivity.
Abstract: An extensive review is given of the results from literature on electron beam induced deposition. Electron beam induced deposition is a complex process, where many and often mutually dependent factors are involved. The process has been studied by many over many years in many different experimental setups, so it is not surprising that there is a great variety of experimental results. To come to a better understanding of the process, it is important to see to which extent the experimental results are consistent with each other and with the existing model. All results from literature were categorized by sorting the data according to the specific parameter that was varied (current density, acceleration voltage, scan patterns, etc.). Each of these parameters can have an effect on the final deposit properties, such as the physical dimensions, the composition, the morphology, or the conductivity. For each parameter-property combination, the available data are discussed and (as far as possible) interpreted. By combining models for electron scattering in a solid, two different growth regimes, and electron beam induced heating, the majority of the experimental results were explained qualitatively. This indicates that the physical processes are well understood, although quantitatively speaking the models can still be improved. The review makes clear that several major issues remain. One issue encountered when interpreting results from literature is the lack of data. Often, important parameters (such as the local precursor pressure) are not reported, which can complicate interpretation of the results. Another issue is the fact that the cross section for electron induced dissociation is unknown. In a number of cases, a correlation between the vertical growth rate and the secondary electron yield was found, which suggests that the secondary electrons dominate the dissociation rather than the primary electrons. Conclusive evidence for this hypothesis has not been found. Finally, there is a limited understanding of the mechanism of electron induced precursor dissociation. In many cases, the deposit composition is not directly dependent on the stoichiometric composition of the precursor and the electron induced decomposition paths can be very different from those expected from calculations or thermal decomposition. The dissociation mechanism is one of the key factors determining the purity of the deposits and a better understanding of this process will help develop electron beam induced deposition into a viable nanofabrication technique.
494 citations
TL;DR: In this article, a wide range of oxygen-containing molecules following impact with electrons of carefully controlled energy is critically reviewed, ranging from diatomics, like O_2 and CO, to large molecules of biological and technological interest.
181 citations
TL;DR: In this paper, the authors collected and reviewed cross section data for electron collisions with carbon monoxide, including total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational and electronic states, ionization, and dissociation.
Abstract: Cross section data are collected and reviewed for electron collisions with carbon monoxide. Collision processes included are total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational and electronic states, ionization, and dissociation. For each process, recommended values of the cross sections are presented, when possible. The literature has been surveyed through to the end of 2013.
178 citations
TL;DR: A complete set of cross sections for all important electron-and proton-impact processes with CHy (y=1−4) impurities and their ions CHy+ is presented in this paper.
Abstract: The critical fusion reactor design issue of tritium codeposition in tokamaks with carbon as wall material is closely linked with the plasma chemistry involving hydrocarbons. A complete set of cross sections for all important electron- and proton-impact processes with CHy (y=1–4) hydrocarbon impurities and their ions CHy+ is presented. The cross sections are derived on the basis of most recent experimental information and well established cross section scaling relationships. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes.
167 citations
TL;DR: In this paper, cross sections and rate coefficients are provided for inelastic collision processes of electrons and protons with CxHy and cxHy+ (x=2,3; 1⩽y ⩽2x+2) hydrocarbon species in a wide range of collision energies and plasma (gas) temperatures.
Abstract: Cross sections and rate coefficients are provided for inelastic collision processes of electrons and protons with CxHy and CxHy+ (x=2,3; 1⩽y⩽2x+2) hydrocarbon species in a wide range of collision energies and plasma (gas) temperatures The considered processes include electron-impact ionization and dissociation of CxHy, dissociative excitation, ionization and recombination of CxHy+ with electrons, and both charge transfer and atom exchange in proton channels are considered separately The presented cross sections are based upon a critical assessment of available experimental data and upon an extensive use of a number of semi-empirical, physically well grounded cross section scaling relationships Information is also provided for the energetics of each individual reaction channel The cross sections and rate coefficients are presented in compact analytic forms
161 citations
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TL;DR: In this paper, a new method was devised for obtaining absolute cross sections of gases relative to H2, and a McLeod gauge was used to obtain the absolute cross section in H2.
Abstract: The total ionization cross sections of He, Ne, Ar, Kr, Xe, H2, D2, N2, O2, CO, NO, CO2, N2O, and CH4 have been measured from threshold to 1000 eV in a total ionization tube. More limited measurements were performed in C2H4 and SF6. Great care was taken to assure complete collection of electron and ion currents, and the absence of spurious instrumental errors. A new method was devised for obtaining absolute cross sections of gases relative to H2, and a McLeod gauge was used to obtain the absolute cross section in H2. The cross sections in NO and O2 could not be obtained by this method, and an approximate correction to direct McLeod‐gauge readings was used for these gases. It is believed that the results are as accurate as is possible with the present method. It is difficult to explain the differences found between cross sections measured by various investigators. McLeod‐gauge errors appear to account for most of the difference in absolute magnitude.
1,758 citations
TL;DR: Measurements of ionization cross sections for the four rare gases He, Ne, Ar, and Kr from 0 to 200 eV agree with the most reliable previous values within \ifmmode\pm\else\textpm\fi{}6%.
Abstract: A new apparatus has been constructed for the measurement of absolute partial electron-impact-ionization cross sections of neutral atoms, molecules, and free radicals. A fast neutral beam is prepared by charge-transfer neutralization of a mass-selected ion beam and is ionized as it crosses an electron beam. From careful analysis of the apparatus, the absolute accuracy of measured cross sections is calculated to be \ifmmode\pm\else\textpm\fi{}12%. Combined with statistical errors, this gives about \ifmmode\pm\else\textpm\fi{}15% for the overall accuracy. Measurements of ionization cross sections for the four rare gases He, Ne, Ar, and Kr from 0 to 200 eV agree with the most reliable previous values within \ifmmode\pm\else\textpm\fi{}6%. The measured Xe ionization cross section is 12% greater than the previous best value. Ratios of double- and triple-ionization to single-ionization cross sections for Ar, Kr, and Xe confirm the recent measurements of Stephan, Helm, and M\"ark [J. Chem. Phys. 73, 3763 (1980)].
351 citations
TL;DR: In this paper, absolute partial cross-sections from threshold to 1000 eV are reported for electron-impact ionization of ionized particles, and the overall uncertainty in the absolute cross-section values for singly charged parent ions is 3.5% and is marginally higher for fragment ions.
Abstract: Absolute partial cross sections from threshold to 1000 eV are reported for electron-impact ionization of ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, and ${\mathrm{O}}_{2}$. Data are presented for the production of ${\mathrm{H}}_{2}^{\mathrm{}+}$ and ${\mathrm{H}}^{+}$ from ${\mathrm{H}}_{2}$; the production of ${\mathrm{N}}_{2}^{\mathrm{}+}$, ${\mathrm{N}}^{+}$+${\mathrm{N}}_{2}^{\mathrm{}2+}$, and ${\mathrm{N}}^{2+}$ from ${\mathrm{N}}_{2}$; and the production of ${\mathrm{O}}_{2}^{\mathrm{}+}$, ${\mathrm{O}}^{+}$+${\mathrm{O}}_{2}^{\mathrm{}2+}$, and ${\mathrm{O}}^{2+}$ from ${\mathrm{O}}_{2}$. The product ions are mass analyzed with a time-of-flight mass spectrometer and detected with a position-sensitive detector whose output provides clear evidence that all energetic fragment ions are collected. The overall uncertainty in the absolute cross-section values for singly charged parent ions is \ifmmode\pm\else\textpm\fi{}3.5% and is marginally higher for fragment ions. Previous cross-section measurements are compared to the present results. \textcopyright{} 1996 The American Physical Society.
264 citations
Abstract: A pulsed electron beam and ion extraction method is used to measure normalized values of partial ionization cross sections for rare gases from threshold to 1000 eV. Cross sections obtained for singly ionized species are used to calibrate the mass transmission efficiency of the ion extraction/analyzer/detection system by the relative flow technique, and this mass transmission curve is then used to determine the absolute cross sections of the multiply ionized species. Total ion cross sections are found by summation of the individual partial cross sections with proper weighting for charge.
255 citations
TL;DR: The total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and SiH6 have been measured for electron energies from threshold to 300 eV.
Abstract: The total and partial electron collisional ionization cross sections for CH4, C2H6, SiH4, and Si2H6 have been measured for electron energies from threshold to 300 eV. Comparisons are made to earlier measurements.
242 citations