Mass spectrometric study of ion-pair processes in diatomic molecules: H2, CO, NO and O2

Locht, Robert; Momigny, J.

doi:10.1016/0020-7381(71)80033-5

Cited by 47 publications

(42 citation statements)

References 28 publications

(42 reference statements)

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“…This is in agreement with our previous experiments on O -produced by electron impact on CO [18] and with the O -kinetic energy distribution obtained by Köllmann [12]. It is also evident from the ionization efficiency curve of () -that several CO * states are involved in the ion pair formation over the range of 21-26 eV electron energy [18]. As shown in fig.…”

Section: Discussionsupporting

confidence: 92%

“…As shown in fig. 5 the first threshold measured at (20.91 ± 0.04) eV belongs to the well defined peak in the first derivative of the C + ionization efficiency curve, corresponding to an ion pair formation through (1) This process has been studied in detail earlier [18]. The examination of the C + ion energy distribution near threshold (see fig.…”

Section: Discussionmentioning

confidence: 90%

“…The energy levels of C and O + are taken from ref. (7) 29.317 C( 3 P) + O + ( 2 P 0 ) (8) 29.746 C( 1 S) + O + ( 2 D 0 ) (9) 30.736 C( 1 D) + O + ( 2 P 0 ) (10) 31.011 C( 5 P 0 ) + O + ( 4 S 0 ) (11) 32.207 C( 5 S 0 ) + O + ( 2 D 0 ) (12) 32.234 C( 1 S) + O + ( 2 P 0 ) (13) 32.430 C( 5 S 0 ) + O + ( 2 P 0 ) (14) 33.928 C( 5 P 0 ) + O + ( 2 D 0 ) (15) 35.532 C( 2 P 0 ) + O + ( 4 S 0 ) (16) 35.987 C( 5 P 0 ) + O + ( 2 P 0 ) (17) 37.226 C( 3 P) + O + ( 4 P) (18) 39.584…”

Section: Discussionmentioning

confidence: 99%

“…As far as ionization efficiency curves are concerned, averaged during 8 h at least, the threshold is measured at the intercept of the linear extrapolation of the highest slope of the one time differentiated ionization efficiency curve and the electron energy axis [16,18]. All threshold energies have been measured independently five times.…”

Section: Data Handling and Significant Figuresmentioning

confidence: 99%

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The dissociative ionization of carbon monoxide

Locht

1977

Chemical Physics

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The dissociative ionization of CO by low energy electron impact into C + + O (or O -) and O + + C (or C -) is investigated using ion energy and mass analysis. The kinetic energy distributions are studied as a function of the impinging electron energy. The threshold energies of C + and O + are measured as a function of the released kinetic energy. The formation of the products in their ground level and with a small amount of kinetic energy mainly occurs through predissociation. The CO + electronic states involved in these processes are tentatively identified. New evidences have been found for the importance of dissociative ionization via autoionization.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Data Handling and Significant Figuresmentioning

confidence: 99%

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The dissociative ionization of carbon monoxide

Locht

1977

Chemical Physics

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“…In addition to the dissociation limit observed at 17.25 eV for the first ion-pair process [16], the plot of the threshold energies as a function of the retarding potential [10] shows, at least, three dissociation limits lying in the ion-kinetic energy range from 0.0 meV to 2740 meV, i.e., 18.73 eV, 20.60 eV and 22.06 eV [7] characterized by the following processes:…”

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The observation of predissociations in the oxygen molecular ion by low-energy electron impact

Schopman

Locht

1974

Chemical Physics Letters

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The kinetic energy distribution of the O + ions formed by dissociative ionization of O2 has been carefully ex-amined in the range of 0.0 to 1.3 eV. In the peak at 600 meV fine structure is observed and interpreted by predissociation. The high energy side of the peak has been ascribed to the predissociation of the 2 ∆ g , B 2 Σ g -and the c 4 Σ u -states of O 2 + . The low energy side of the peak is presumably due to the predissociation of the b 4 Σ g -state or the Φ u state of O 2 + or to autoionizing predissociation.During the last few years much attention has been paid to the dissociation of diatomic molecules. One of the dissociation channels a molecule can choose is the predissociation observed in several neutral and ionized species. Besides the optical spectroscopy methods, predissociations have been investigated by a variety of techniques such as "metastable ion" mass spectrometry [1,2], high resolution translational spectroscopy [3,4] as well as photoelectron spectroscopy [5,6].The dissociation of the oxygen molecular ion has been the subject of several papers. Doolittle et al. [7] obtained the kinetic energy distribution curve of O + from O 2 by using photoionization mass spectrometry. Freund [8] and Kieffer et al. [9] studied the kinetic energy carried away by the 0 ions formed by electron impact on O 2 . These authors ascribed the first broad and structureless peak, with a maximum at 850 meV, to O + fragment ions formed by predissociation, although no direct experimental evidence was found for this mechanism. Recently Danby and Eland [5] showed experimentally the existence of a predissociation of O 2 by using the photoelectronphotoion coincidence technique.The purpose of this paper is to report our results obtained for the kinetic energy analysis of the O + ions formed by electron impact on molecular oxygen;The instrument used, as well as the experimental conditions will be described elsewhere [10]. Briefly, the ions formed in a conventional Nier-type ion source pass through a retarding potential system before entering into a quadrupole mass spectrometer. The ion current is, at fixed electron energy, continuously scanned with respect to the retarding potential or with respect to electron energy at fixed retarding potential. The first derivative of either the retarding curves or the ionization efficiency curves is stored in a multichannel analyser and plotted on an X-Y recorder.A preliminary report [11] has been devoted to the kinetic energy distribution curve of O + from O 2 , spread over a broad energy range (0 to 12 eV). These results will be published elsewhere [10]. In this letter we will limit our discussion to the results obtained in the energy range of 0 to 1.3 eV.An example of a kinetic energy distribution of O + from O 2 , as observed by the impact of 25 eV electrons, is shown in fig. 1.The first peak maximum is measured at 0.0 eV coinciding with the maximum of the thermal distribution of the molecular ion O 2 , taken as the origin of the kinetic energy scale. The second maximum, meas...

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Formation of O−2 in charge transfer collisions of fast molecular hydrogen ions with O2 molecules

Lork

Tybislawski

Bends

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract.Cross sections for the production of O2-in charge transfer collisions of fast molecular hydrogen ions (Hf, Dr, Hf, and Df of 10 to 140 keV kinetic energy) with 02 molecules have been determined by means of a time-of-flight mass spectrometer analysing the slow negative product ions from the collisions. Within the measuring accuracy equivelocity Hf and Df ions have the same cross sections for the generation of Of. The projectile velocity dependence curve of the cross section passes through a broad maximum with a peak value of about 6.5 x 10 -is cm 2 around the Bohr velocity (25 keV/u) before showing an asymptotic decrease still within the limited energy range under investigation that is in inverse proportion to the square of velocity. Throughout the examined energy range H + ions yield a cross section which is about 1.4 times larger than that of Hf ions of the same velocity. The fragment ion O-has been found to appear with cross sections between 10 -19 and 10 -28 cm 2 upon collisional excitation in the energy range under investigation, with ever decreasing intensity when the energy of the positive hydrogen ions, the proton included, was increased.

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Mass spectrometric study of ion-pair processes in diatomic molecules: H2, CO, NO and O2

Cited by 47 publications

References 28 publications

The dissociative ionization of carbon monoxide

The dissociative ionization of carbon monoxide

The observation of predissociations in the oxygen molecular ion by low-energy electron impact

Formation of O−2 in charge transfer collisions of fast molecular hydrogen ions with O2 molecules

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