Electron impact ionization cross sections of molecules

Margreiter, D.; Wälder, G.; Deutsch, Hans‐Peter; Poll, H.-U.; Winkler, C.; Stephan, K.; Märk, T. D.

doi:10.1016/0168-1176(90)85073-b

Cited by 75 publications

(39 citation statements)

References 55 publications

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“…In a recent investigation we have studied the extraction and transmission conditions for fragment ions and have shown [9,10] that mass analyzed y-integrated ion signals not only saturate for parent ions, but appear to saturate also for fragment ions if the potential difference between the collision chamber and lens L 2, Uc:r2, is large enough. Nevertheless, it was found [8], that smaller fragment ions of polyatomic molecules (which have larger excess kinetic energies) are not extracted from the ion source with the same efficiency as the larger fragment ions. In order to account for this discrimination at the ion source exit slits an additional correction procedure -described below -has been developed in our laboratory.…”

Section: T E X P E R I M E N T a Lmentioning

confidence: 96%

“…Detailed descriptions of the apparatus [6], of the experimental procedure [7,8] and of the method of detecting ions with high translational kinetic energies [8] have been given previously. Briefly, the experimental set-up used consists of a conventional three-electrode type electron impact ion source, and a high-resolution double focussing (reversed geometry) sector field mass spectrometer.…”

Section: T E X P E R I M E N T a Lmentioning

confidence: 99%

“…In the present work, electron impact ionization of propane (C3H8) was studied using the ion beam deflection technique [7,8] and a double focussing mass spectrometer in conjunction with a recently developed correction procedure that accounts for discrimination due to the initial kinetic energy of fragment ions [8]. The relative, corrected partial ionization cross sections of C3 H+ , C3 H+ , C3H + , C3 H+ , C3 H+ , C3H3 + , C3 H+ , C3H +, C3 +-C2 H+, C2H4 +, C2H3 + , C2H2 +, C2H +, C +-CH3 + 2 ~ CH + , CH+, C + ; C3H ~+, C3H ]+, C3H3 2 + and C3 H2+, were determined from threshold up to 950 eV.…”

Section: Introductionmentioning

confidence: 99%

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Absolute partial and total electron impact ionization cross sections for C3H8 from threshold up to 950 eV

Grill

Wälder

Margreiter

et al. 1993

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Electron impact ionization of propane (C3H8) was studied using the ion beam deflection technique and a double focussing mass spectrometer in conjunction with a recently developed correction procedure that accounts for discrimination due to the initial kinetic energy of fragment ions. The relative corrected partial ionization cross sections for the production of C3H~-, C3 H+, C3HJ , C3Hff, C3H {, C3H3 ~, C3H +, C3 H+, C~-; C2H if, Call2, C2 H [ , C2H + , C2 H+ , C~' C H + , CH +, CH + , C +. c ~ H2+, " 3 5 C3H42+, C3H~ + and C3H~ + were determined from threshold up to 950 eV. Absolute partial ionization cross sections were obtained by charge weighted summing of all the observed partial ionization cross sections and by normalizing to a recent accurate determination of the total ionization cross section at 100 eV by Djuric et al. 1991. The absolute total ionization cross section curve obtained is in excellent agreement in shape and magnitude with the low energy data ( < 200 eV) of Djuric et al. 199I and the high energy data points of Schram et al. i966.

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Section: T E X P E R I M E N T a Lmentioning

confidence: 96%

Section: T E X P E R I M E N T a Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Absolute partial and total electron impact ionization cross sections for C3H8 from threshold up to 950 eV

Grill

Wälder

Margreiter

et al. 1993

Z Phys D - Atoms, Molecules and Clusters

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“…This has been done using a beam of CF2C1Br gas and adjusting the operating parameters of the electron bombardment detector in order to match the measured abundance spectra with the published values of [24]. After the completion of this work we realized that fragmentation ratios published before 1988 can be seriously in error, since the discrimination of energetic fragments was not properly taken into account [25]. Therefore we recalibrated the transmission of the quadrupole against those measured recently for CF4 [26] and corrected the data accordingly.…”

Section: Calibration Of the Mass Spectrometermentioning

confidence: 96%

Electron bombardment induced fragmentation of size selected neutral (D2O) n clusters

Buck¹,

Winter²

1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The fragmentation behaviour of size selected neutral (D20)~ clusters with n<4 after ionization with 70 eV electrons is subject of this work. Size selection by scattering the cluster beam from a He target beam in combination with a quadrupole mass filter and time resolved measurements at specific laboratory angles enables us to determine the neutral precursor masses of the detected ions. The measured fragment pattern is dominated by deuterated ions of the form (D20),,_xD + with x > 1. The dimer fragmentation which leads with a probability of 62.5% to the D3 O+ ion and with 37.5% to D20 ÷ can be explained by fast intracluster ion-molecule reactions of charged monomer fragments reacting with the partner molecule. For larger clusters the fragmentation process can be rationalised by the creation of an initially highly excited D30+(DeO)x complex which is stabilized by evaporating additional monomer units with the main fragment channel (D20)D ÷ for n=3 and (D20)2D + for n=4. With increasing cluster size an increasing tendency of evaporation of more than one water monomer unit has been observed.

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“…Measurements of electron impact dissociative ionization of gaseous SF 6 give the threshold energy for F + formation somewhere in the range of 30-50 eV [13,14], very different from F -. The comparison of ESDIAD images for F + and F -should provide insights into the mechanisms of ion formation.…”

Section: Introductionmentioning

confidence: 99%

Effects of electron irradiation on structure and bonding of SF6 on Ru(0001)

Faradzhev

Kusmierek

Yakshinskiy

et al. 2003

Low Temperature Physics

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Electron-stimulated desorption ion angular distribution (ESDIAD) and temperature-programmed desorption (TPD) techniques have been employed to study radiation-induced decomposition of fractional monolayer SF6 films physisorbed on Ru(0001) at 25 K. Our focus is on the origin of F+ and F− ions, which dominate ESD from fractional monolayers. F− ions escape only in off-normal directions and originate from undissociated molecules. The origins of F+ ions are more complicated. The F+ ions from electron-stimulated desorption of molecularly adsorbed SF6 desorb in off-normal directions, in symmetric ESDIAD patterns. Electron beam exposure leads to formation of SFx (x=0–5) fragments, which become the source of positive ions in normal and off-normal directions. Electron exposure >1016 cm−2 results in decomposition of the entire adsorbed SF6 layer.

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Electron impact ionization cross sections of molecules

Cited by 75 publications

References 55 publications

Absolute partial and total electron impact ionization cross sections for C3H8 from threshold up to 950 eV

Absolute partial and total electron impact ionization cross sections for C3H8 from threshold up to 950 eV

Electron bombardment induced fragmentation of size selected neutral (D2O) n clusters

Effects of electron irradiation on structure and bonding of SF6 on Ru(0001)

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