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Carmen Cisneros

Bio: Carmen Cisneros is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Photoionization & Ion. The author has an hindex of 18, co-authored 118 publications receiving 1051 citations.


Papers
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Journal ArticleDOI
TL;DR: A pulsed Townsend swarm technique has been used to study electron-ionization and electron attachment processes in methane over the density-normalized electrical field strength, in the range 1.2-30 fV (120-3000 Td) as discussed by the authors.
Abstract: A pulsed Townsend swarm technique has been used to study electron-ionization and electron-attachment processes in methane over the density-normalized electrical field strength, , in the range 1.2-30 fV (120-3000 Td). The time-resolved ionic avalanches were obtained under conditions such that the occurrence of electron-attachment processes was detected unambiguously. The analysis of these avalanche pulses resulted in values of the effective ionization coefficients and positive-ion mobilities over the above range. To the best of our knowledge, no values of positive-ion mobilities had been published before for Td. The electron-attachment effects were observed up to Td.

56 citations

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TL;DR: In this paper, the authors used a drift tube with double mass spectrometry to measure the mobility of a set of systems over a wide range of the density-normalized electric field.
Abstract: We have used a drift tube with double mass spectrometry to measure the mobility of ${\mathrm{He}}^{+},$ ${\mathrm{Ne}}^{+},$ ${\mathrm{Ar}}^{+},$ ${\mathrm{N}}_{2}^{+},$ ${\mathrm{O}}_{2}^{+},$ and ${\mathrm{CO}}_{2}^{+}$ in their parent gas over a wide range of the density-normalized electric field, $E/N,$ from 70 to $12500\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}{\mathrm{V}\mathrm{}\mathrm{m}}^{2}.$ In all cases, the $E/N$ ranges have exceeded those hitherto found in the literature, especially those of ${\mathrm{Ar}}^{+}$ in Ar and ${\mathrm{N}}_{2}^{+}$ in ${\mathrm{N}}_{2}.$ Our mobility data are in fair to excellent agreement with previous experimental data in the overlap range. Recent calculated data for the mobility of ${\mathrm{Ar}}^{+}$ in Ar show excellent agreement with our data at high $E/N,$ while fair agreement was observed for the calculated data of the systems ${\mathrm{N}}_{2}^{+}$ in ${\mathrm{N}}_{2}$ and ${\mathrm{O}}_{2}^{+}$ in ${\mathrm{O}}_{2}.$ Also, the ${\mathrm{Ar}}^{+}$ in Ar mobilities for $E/Ng10\mathrm{kTd}$ were found in excellent agreement with those derived from the measurement of the mean ion energy in diffuse Townsend discharges $(1{\mathrm{T}\mathrm{d}=1\mathrm{}\mathrm{t}\mathrm{o}\mathrm{w}\mathrm{n}\mathrm{s}\mathrm{e}\mathrm{n}\mathrm{d}=10}^{\mathrm{\ensuremath{-}}21}{\mathrm{}\mathrm{V}\mathrm{}\mathrm{m}}^{2}).$ To the best of our knowledge, over some $E/N$ ranges, our data were found to be the first to be reported.

53 citations

Journal ArticleDOI
TL;DR: In this paper, the lifetime of the 1s2s 2 2p 22 D, 2 P and 2 S autoionizing states of C + was determined by measurement of the natural linewidth.
Abstract: Lifetimes for K-shell vacancy states in atomic carbon have been determined by measurement of the natural linewidth of the 1s → 2p photoexcited states of C + ions. The K-shell vacancy states produced by photoionization of atomic carbon are identical to those produced by 1s → 2p photoexcitation of a C + ion: 1s2s 2 2p 22 D, 2 P, and 2 S autoionizing states occur in both cases. These vacancy states stabilize by emission of an electron to produce C 2+ ions. Measurements are reported for the lifetime of the 1s2s 2 2p 22 D, 2 P and 2 S autoionizing states of C + :6 .3± 0.9 fs, 11.2 ± 1.1 fs and 5.9 ± 1.3 fs respectively. Knowledge of such lifetimes is important for comparative studies of the lifetimes of Kshell vacancies in carbon-containing molecules, benchmarking theory, and interpreting satellite x-ray spectra from astrophysical sources such as x-ray binaries. Absolute cross sections were measured for both ground-state and metastable-state ions providing a stringent test of state-of-the-art theoretical calculations. Carbon is ubiquitous in nature and is the building block of life. This atom in its various stages of ionization has relatively few electrons, and is thus amenable to theoretical study. Lifetimes

52 citations

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TL;DR: In this paper, photoionization of the 1S ground state and 3Po metastable states of C2+ ions in the photon energy range 40.8-56.9 eV at a resolution of 30 meV was investigated.
Abstract: We have investigated photoionization (PI) of the 1S ground state and 3Po metastable states of C2+ ions in the photon energy range 40.8-56.9 eV at a resolution of 30 meV. Absolute PI cross sections have been measured using a photon-ion merged beam arrangement at the Advanced Light Source. Detailed calculations using the semi-relativistic Breit-Pauli R-matrix approach suggest a fraction of 40% of metastable ions in the primary beam of the experiment. The present results are discussed in the light of previous electron-C3+-ion photorecombination (PR) studies. As an example, the role of the intermediate C2+(2p4d 1P) resonance in both PI and PR is analysed.

46 citations

Journal ArticleDOI
TL;DR: The absolute cross-section measurements for resonant double photoexcitation of Li + ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below the 2s2p, 2(0, 1) + resonance, to 198 eV (the region of the double ionization threshold) as discussed by the authors.
Abstract: Absolute cross-section measurements for resonant double photoexcitation of Li + ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below the 2s2p, 2(0, 1) + resonance, to 198 eV (the region of the double ionization threshold). The measurements have been made using the photon–ion merged-beam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory, USA. The absolute cross-section measurements show excellent agreement with theoretical results from the R-matrix plus pseudo-state (RMPS) method. Comparisons between theory and experiment for the Auger resonance energies, autoionization linewidth (� ) and the Fano line profile index q for several members of the principal 2snp, 2(0, 1) + and 3snp, 3(1, 1) + Rydberg series found in the photoionization spectra for the 1 P o symmetry show satisfactory accord. (Some figures in this article are in colour only in the electronic version)

41 citations


Cited by
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01 Jan 1999

643 citations

Journal ArticleDOI
TL;DR: In this article, the behavior of high pressure gases such as N/sub 2/ and SF/sub 6/N/sub 3/ mixtures that can be realistically considered as acceptable intermediate or long-term replacements for pure S 6/ in some HV applications is discussed.
Abstract: The widespread use of SF/sub 6/ by the electric power and other industries has led to increased concentrations of SF/sub 6/ in the atmosphere. This causes concern as to possible effects on global warming, because SF/sub 6/ is a potent greenhouse gas. This paper first touches on this issue and then documents the behavior of high pressure gases such as N/sub 2/ and SF/sub 6//N/sub 2/ mixtures that can be realistically considered as acceptable intermediate or long-term replacements for pure SF/sub 6/ in some HV applications. The possible use of dilute SF/sub 6//N/sub 2/ mixtures as an alternative to pure SF/sub 6/ for some of industry's insulation needs (albeit at higher pressure) is documented, and existing knowledge on these mixtures and on the individual components (N/sub 2/ and SF/sub 6/), both basic and applied, is compiled. A guide to existing literature is provided. >

294 citations

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TL;DR: In this article, a review of the results obtained in the period 2006-2014 in the field of plasma-assisted combustion, and in particular the results on ignition and combustion triggered or sustained by pulsed nanosecond discharges in different geometries, is presented.
Abstract: This review covers the results obtained in the period 2006–2014 in the field of plasma-assisted combustion, and in particular the results on ignition and combustion triggered or sustained by pulsed nanosecond discharges in different geometries. Some benefits of pulsed high voltage discharges for kinetic study and for applications are demonstrated. The necessity of and the possibility of building a particular kinetic mechanism of plasma-assisted ignition and combustion are discussed. The most sensitive regions of parameters for plasma–combustion kinetic mechanisms are selected. A map of the pressure and temperature parameters (P–T diagram) is suggested, to unify the available data on ignition delay times, ignition lengths and densities of intermediate species reported by different authors.

274 citations

Journal ArticleDOI
TL;DR: Trois types de spectrometrie de masse sont etudies: the NIBS (neutralized ion beam spectroscopy), the NRMS (neutralization-reionization mass spectrometry) and the CIDI (collision-induced dissociative ionization) as discussed by the authors.
Abstract: Trois types de spectrometrie de masse sont etudies: la spectrometrie NIBS («Neutralized ion beam spectroscopy»), la spectrometrie NRMS («Neutralization-reionization mass spectrometry») et la spectrometrie de masse CIDI («Collision-induced dissociative ionization»)

239 citations

Journal ArticleDOI
TL;DR: In this article, the fundamental rate data for recently proposed chemical-kinetics models of corona and glow-type discharges in sulfur hexafluoride (SF/sub 6/), used as an insulating gas in HV apparatus, is reviewed.
Abstract: It is known that sulfurhexafluoride (SF/sub 6/), used as an insulating gas in HV apparatus, will oxide in electrical discharges in the presence of oxygen or water vapor to form various reactive and stable by-products. In order to interpret experimental data on rates of oxidation and by product formation in discharges, meaningfully, it is necessary to apply theoretical chemical kinetics models that utilize rates for numerous gas-phase processes as functions of gas temperature and/or electric-field-to-gas-density ratio. Current knowledge about the fundamental collision processes involving electrons, ions, free radicals, and molecules needed to understand the gas-phase discharge chemistry in SF/sub 6/ is reviewed. Implications of the fundamental rate data reviewed here for recently proposed chemical-kinetics models of corona and glow-type discharges in SF/sub 6/ are discussed. >

225 citations