Role of adsorption effects on absolute electron-molecule cross-section calibration using the relative flow technique

Homem, M. G. P.; Iga, I.; Sugohara, R. T.; Sanches, I. P.; Lee, M. T.

doi:10.1063/1.3525799

Cited by 23 publications

(36 citation statements)

References 26 publications

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“…The DCS was measured using the same experimental setup and procedure presented in several previous works [14][15][16][17][18][19][20], Briefly, the intensities of the elastically scattered electrons were measured using a crossed electron-beam-molecularbeam geometry. The scattered electrons are energy filtered by a retarding-field energy analyzer with a resolution of about 1.5 eV.…”

Section: Methodsmentioning

confidence: 99%

“…For each measurement, approximately 1 mL of the liquid sample was put into a small vial attached to the gas-handling manifold [14] and then underwent a pretreatment for elimination of atmo spheric air through several freeze-thaw cycles. A gaseous DMS beam was formed by the saturated vapor above the liquid, and its purity was checked during the measurements using a resid ual gas analyzer attached to the electron spectrometer chamber.…”

Section: Methodsmentioning

confidence: 99%

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Theoretical and experimental investigation of electron collisions with dimethyl sulfide

et al. 2015

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We report a joint theoretical-experimental investigation of elastic electron scattering by dimethyl sulfide in the low-and intermediate-energy regions. More specifically, experimental differential, integral, and momentumtransfer cross sections are given in the 30-800 eV and 10°-130° ranges. Theoretical cross sections are reported in the 1-500 eV interval. The experimental differential cross sections were determined using a crossed electronbeam-molecular-beam geometry, whereas the absolute values of the cross sections were obtained using the relative-flow technique. Theoretically, a complex optical potential was used to represent the collision dynamics, and a single-center expansion method combined with the Pade approximant method was used to solve the scattering equations. Our experimental data are in good agreement with the present calculated data but strongly disagree with those reported in a previous investigation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Theoretical and experimental investigation of electron collisions with dimethyl sulfide

et al. 2015

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“…Since the closed volume is constant, we can assume that the pressure rise over time (measured by an MKS Baratron) is proportional to the outflow of vapors from the sample container. Here, it should be noted that for vapors, unlike for gaseous targets (e.g., Ar), effects such as adsorption on surfaces may significantly affect the flow rate determination and consequently the absolute differential cross sections, which have been investigated in detail recently by Homem et al [25]. However, the influence of these effects was strongly reduced in the present case because the whole system (sample, pipes, valves, and needle) was heated, as also pointed out in [25].…”

Section: Methodsmentioning

confidence: 99%

“…Here, it should be noted that for vapors, unlike for gaseous targets (e.g., Ar), effects such as adsorption on surfaces may significantly affect the flow rate determination and consequently the absolute differential cross sections, which have been investigated in detail recently by Homem et al [25]. However, the influence of these effects was strongly reduced in the present case because the whole system (sample, pipes, valves, and needle) was heated, as also pointed out in [25]. Indeed, we have compared flow rates of NMF vapors measured at room temperature and when the gas line was maintained at 50 • -60 • , under the same pressures behind the needle, the results showed a non-negligible difference.…”

Section: Methodsmentioning

confidence: 99%

Absolute cross sections for elastic electron scattering from methylformamide

et al. 2012

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Elastic electron scattering from gaseous methylformamide (N -methylformamide, C 2 H 5 NO) has been investigated. Absolute elastic differential cross sections (DCSs) were determined both experimentally and theoretically for the incident energies from 50 to 300 eV. The measurements were performed using a cross-beam technique, for scattering angles from 20 • to 110 • . Relative elastic DCSs were measured as a function of both the angle and the incident energy and the absolute DCSs were determined using the relative flow method. The calculations of electron interaction cross sections are based on a corrected form of the independent-atom method, known as the SCAR (screen corrected additivity rule) procedure and using an improved quasifree absorption model. Calculated integral cross sections have been presented, as well, both for methylformamide and formamide, in the energy range 10-1000 eV, and discussed. The results are compared with and discussed regarding existing data for other small molecules representing building blocks of large biomolecules.

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“…The relative flow rate has been determined by closing an outlet to the chamber, admitting target gases into a closed constant volume and then measuring the pressure increase in time (measured by a MKS baratron). 8,10 The influence of adsorption on surfaces to the relative flow measurements 37 is reduced in the present case, because the furan molecule has a very high vapor pressure and a small dipole moment (see also Ref. 37).…”

Section: Methodsmentioning

confidence: 90%

Absolute cross sections for electron scattering from furan

Maljković

Blanco

Čurík

et al. 2012

The Journal of Chemical Physics

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We report results of measurements and calculations of absolute cross sections for electron scattering from furan molecules (C 4 H 4 O). The experimental absolute differential cross sections (DCSs) for elastic electron scattering were obtained for the incident energies from 50 eV to 300 eV and for scattering angles from 20 o to 110 o , by using a crossed electron-target beam setup and the relative flow technique for calibration to the absolute scale. The calculations of the electron interaction cross sections are based on a corrected form of the independent-atom method, known as the screening corrected additivity rule (SCAR) procedure and using an improved quasifree absorption model. The latter calculations also account for rotational excitations in the approximation of a free electric dipole and were used to obtain elastic DCSs as well as total and integral elastic cross sections which are tabulated in the energy range from 10 to 10 000 eV. All SCAR calculated cross sections agree very well with both the present and previously published experimental results. Additionally, calculations based on the first Born approximation were performed to calculate both elastic and vibrationally inelastic DCSs for all the modes of furane, in the energy range from 50 eV to 300 eV. The ratios of the summed vibrational to elastic DCSs are presented and discussed. Finally, the present results for furan are compared with previously published elastic DCSs for the tetrahydrofuran molecule and discussed.

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Role of adsorption effects on absolute electron-molecule cross-section calibration using the relative flow technique

Cited by 23 publications

References 26 publications

Theoretical and experimental investigation of electron collisions with dimethyl sulfide

Theoretical and experimental investigation of electron collisions with dimethyl sulfide

Absolute cross sections for elastic electron scattering from methylformamide

Absolute cross sections for electron scattering from furan

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