He(I) photoelectron spectroscopy of halogen atoms

Leeuw, D.M. de; Mooyman, R.; Lange, C.A. de

doi:10.1016/0009-2614(78)80090-6

Cited by 50 publications

(9 citation statements)

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“…The break in the IEC of I (g) at about 15 eV obviously belongs to the appearance energy of I (g) from LiI(g), whereas the low energy threshold value is probably the ionization energy of I(g) (at about 10 eV). This latter statement can be confirmed by comparing the two threshold data of I (g) and HI (g) with the literature ionization energies of I(g) 29 and HI(g), 1,30 respectively. The ionization and appearance energies obtained from the individual runs and thus the mean values are shown in Table 2.…”

Section: Ionization and Appearance Energiessupporting

confidence: 61%

The evaporation thermodynamics of lithium iodide. Mass spectrometric andab initio studies

Bencze

Lesar

Popović

1998

Rapid Commun. Mass Spectrom.

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The vaporization of LiI was investigated in the range between 583 and 726 K by Knudsen effusion mass spectrometry (KEMS). The ionization or the appearance energies (IE or AE) of all kinds of ions formed from the equilibrium vapour over solid lithium iodide were determined using Vogt and Pascual's deconvolution method. For the determination of vapour pressure two methods, viz. mass-loss Knudsen effusion and Knudsen effusion mass spectrometry were applied. The mean natural logarithms of the equilibrium vapour pressures (in Pa) of monomer and all kinds of oligomers, that can be detected using KEMS, as a function of temperature, can be expressed as follows: ln p LiI À22240 AE 450aT 28X03 AE 0X66 between 583 and 723 K ln p Li 2 I 2 g À21940 AE 390aT 28X46 AE 0X60 between 583 and 726 K ln p Li 3 I 3 g À27300 AE 660aT 31X5 AE 1X1 between 643 and 726 K ln p Li 4 I 4 g À24820 AE 540aT 25X65 AE 0X66 between 668 and 726 K The molecular structure and the harmonic vibrational frequencies of (LiI) n species (n = 1,2,3,4) were predicted using ab initio molecular orbital methods. Both the bond dissociation energies and the enthalpy changes of dissociation of (LiI) n oligomers were evaluated and compared with the measured enthalpy change data. Using the calculated geometry and the vibration frequencies, the thermodynamic functions of (LiI) n could be calculated, making it possible to compare the second and third law thermodynamic data. # 1998 John Wiley & Sons, Ltd. Received 24 February 1998; Revised 7 May 1998; Accepted 25 May 1998 The vaporization of LiI has been previously studied by a very limited number of investigators using Knudsen effusion mass spectrometry.1-3 For the determination of the partial pressures and the thermodynamic properties of the species present in the equilibrium vapour over condensed LiI, as a first step, the assignment of the ions formed by electron impact has to be determined. Literature values for ionization (IE) and appearance energies (AE) can be found in the articles of Friedman 1 and Platel, 4 but appropriate values for tetrameric ions have not been determined so far. The latter authors determined the values of IE and of AE using the vanishing current and linear extrapolation methods, respectively. We have shown in several articles [5][6][7] that linear extrapolation is not a suitable method in most cases. Instead of linear extrapolation Vogt and Pascual's deconvolution method 8 was applied in the present study. Since the determination of ionization and appearance energies does not provide quantitative information concerning the neutral precursors of the ions, Gorokhov 2 and Berkowitz et al.3 used a double-oven Knudsen apparatus for the apportionment of the total ion currents. A double-oven Knudsen apparatus was first used by Miller and Kusch. 9 Milne 10 derived a relationship for the determination of the relative cross section of a dimeric molecule to that of a monomeric one, assuming chemical equilibrium in the gas phase and viscous flow between the two compartments of the cell (the mea...

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Section: Ionization and Appearance Energiessupporting

confidence: 61%

The evaporation thermodynamics of lithium iodide. Mass spectrometric andab initio studies

Bencze

Lesar

Popović

1998

Rapid Commun. Mass Spectrom.

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“…Masses associated with molecules observable in our TOF system (IP < 10.49 eV) are included in the reaction schemes for comparison with the mass spectra. Ionization potentials important for this work are listed in Table . − …”

Section: Resultsmentioning

confidence: 99%

Radical Chemistry in the Thermal Decomposition of Anisole and Deuterated Anisoles: An Investigation of Aromatic Growth

et al. 2010

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The pyrolyses of anisole (C(6)H(5)OCH(3)), d(3)-anisole (C(6)H(5)OCD(3)), and d(8)-anisole (C(6)D(5)OCD(3)) have been studied using a hyperthermal tubular reactor and photoionization reflectron time-of-flight mass spectrometer. Gas exiting the reactor is subject to an immediate supersonic expansion after a residence time of approximately 65 mus. This allows the detection of highly reactive radical intermediates. Our results confirm that the first steps in the thermal decomposition of anisole are the loss of a methyl group to form phenoxy radical, followed by ejection of a CO to form cyclopentadienyl radical (c-C(5)H(5)); C(6)H(5)OCH(3) --> C(6)H(5)O + CH(3); C(6)H(5)O --> c-C(5)H(5) + CO. At high temperatures (T(wall) = 1200 degrees C - 1300 degrees C) the c-C(5)H(5) decomposes to propargyl radical (CH(2)CCH) and acetylene; c-C(5)H(5) --> CH(2)CCH + C(2)H(2). The formation of benzene and naphthalene is demonstrated with 1 + 1 resonance-enhanced multiphoton ionization. Propargyl radical recombination is a significant benzene formation channel. However, we show the majority of benzene is formed by a ring expansion reaction of methylcyclopentadiene (C(5)H(5)CH(3)) resulting from methyl radical addition to cyclopentadienyl radical; CH(3) + c-C(5)H(5) --> C(5)H(5)CH(3) --> C(6)H(6) + 2H. The naphthalene is generated from cyclopentadienyl radical recombination; 2c-C(5)H(5) --> C(5)H(5)-C(5)H(5) --> C(10)H(8) + 2H. The respective intermediate amu 79 and 129 species associated with these reactions are detected, confirming the stepwise nature of the decompositions. These reactions are verified by pyrolysis studies of cyclopentadiene (C(5)H(6)) and C(5)H(5)CH(3) obtained from rapid thermal dissociation of the respective dimer compounds, as well as pyrolysis studies of propargyl bromide (BrCH(2)CCH).

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“…However, due to the difficulties inherent in producing and handling such a reactive species, experimental determinations of partial photoionization cross sections (o;) and asymmetry parameters (P, ) of Cl are scarce or nonexistent. The first Heta (21. De Leeuw, Mooyman, and De Lange [20] and by Kimu-ra, Yamazaki, and Achiba [21].The latter also presented relative differential cross sections for the 3p [27 -32] and photoionization [25] experiments. In addition to the resonance energies, the high-resolution ionyield measurements of Ruscic and Berkowitz [25] yielded information about the shapes and widths of these resonances.…”

Section: Introductionmentioning

confidence: 99%

Angle-resolved photoelectron spectrometry of atomic chlorine using synchrotron radiation

et al. 1992

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Using synchrotron-radiation-based angle-resolved photoelectron spectrometry, the Cl 3s3p'('P2~o)np and 3s3p'('Pl)np autoionizing Rydberg series are studied by monitoring the relative partial photoionization cross sections and asymmetry parameters of the 3p ' 'P2 l o, 'D2, and 'So ionic states between 21.75 and 27.75 eV. The Rydberg series converging upon the 3s ' 'P&, 'Pl, and 'Po thresholds are clearly resolved. Rydberg levels up to n = 14 can be identified in the ('P2 & 0)np series, while the ('P;)np Rydberg series can be observed up to n =10. The relative partial cross sections are placed on an absolute scale using previous data obtained with an electron spectroscopy modulation method. The present experimental results for the Cl (P2 I p)np and ('P l)np Rydberg series are compared with those of the Ar 3s3p (S j&2)np series, and with theoretical results of a nonrelativistic many-body perturbation theory calculation. The 'P2 & 0 and 'Pl ionization thresholds obtained from the Rydberg series agree very well with the ionization limits calculated on the basis of the Cl II spectrum, and with the ionization energies determined from a 3s ' photoelectron spectrum. Autoionization phenomena due to 3s'3p'~3s'3p'nln'l' two-electron excitations are observed in the 'P; resonance region. PACS number(s): 32.80.Fb, 32.80.Dz ' P2, p 'D2, and 'Sp ionic states measured at 90 with respect to the unpolarized He I a photon beam. In an electron spectroscopy modulation experiment Van der Meer, Butselaar, and De Lange [22] determined the absolute photoionization cross section of the P2, p components using 90 data and calculated P, values. In 1988 Peel and Von Nagy-Felsobuki [23] published another Hei a photoelectron spectrum of Cl, but no absolute or relative cross sections were given. Only very recently [24] we have employed the continuum of synchrotron radiation to extend these photoelectron spectroscopic studies beyond the Hera energy. At present, no measurements of the P; parameters of the 3p ' ionic states have been reported. A more favorable situation exists with regard to the total photoionization cross section (o), which, using an experimentally less demanding mass-resolved ion detection technique, has been measured from threshold at 12.96 eV to about 60 eV [25,26]. Resonance structure due to autoionization phenomena provides direct evidence of electron correlations and is therefore of considerable interest. The energies of the autoionizing 3s 3p (Pz & o, 'D2, 'So)ns, nd 1 Rydberg levels have been determined in photoabsorption 2468 1992 The American Physical Society 'This work; see text. bExperimental results of Van der Meer, Butselaar, and De Lange [22]. 'Experimental results of Samson, Shefer, and Angel [26]. Close-coupling results of Conneely, Smith, and Lipsky [5]. 'Hartree-Fock results of Starace and Armstrong [6]. Random-phase approximation with exchange results of Starace and Armstrong [6]. 'RPAE results of Cherepkov and Chernysheva [7]. "RPAE results of Cherepkov and Chernysheva [g]. 'Many-body perturbation theory results...

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He(I) photoelectron spectroscopy of halogen atoms

Cited by 50 publications

References 8 publications

The evaporation thermodynamics of lithium iodide. Mass spectrometric andab initio studies

The evaporation thermodynamics of lithium iodide. Mass spectrometric andab initio studies

Radical Chemistry in the Thermal Decomposition of Anisole and Deuterated Anisoles: An Investigation of Aromatic Growth

Angle-resolved photoelectron spectrometry of atomic chlorine using synchrotron radiation

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