Gas-phase Photoelectron Spectra Research Articles

Buckminsterfullerene C60 — a surface with curvature and interesting properties

Molecular cluster calculations within the local density approximation have been performed in a study of the electronic structure of the truncated icosahedral C60 also known as “Buckminsterfullerene” and C60 doped with K, B and N. Evaluated ionisation energies for C60 are found to be in good agreement with recently observed gas phase and solid-state photoelectron spectra. Excitation energies evaluated in the 1–10 eV energy range are also found to reproduce UV, IR and HREELS spectra. Calculations for the KC60 molecule, with the K atom located at the centre of the cage, show how the valence electron from K is transferred to the LUMO state of the bare C60 molecule. Doping with a B or N atom in the centre of the cage creates a different structure with a partly occupied level in the band gap, similar to the donor and acceptor levels in traditionally doped semiconductors. Doping by substitution of two of the carbon atoms in the cage with X = B or N, as modelled with the C58X2 cluster, gives a different structure with a splitting of the HOMO and LUMO levels in the bare C60 molecule.

High resolution Si 2p gas phase photoelectron spectra of model silicon compounds: implications for hydrogen adsorbed on a silicon surface

High resolution Si 2p gas phase photoelectron spectroscopy has been used to measure the vibrational energy spacing in SiH 4 (0.295 eV) and SiD 4 (0.212 eV). These values are compared with those measured for the chemical shift (0.30 eV/hydrogen atom) of model compounds which mimic the effects of zero, one, two and three hydrogen atoms bonded to a silicon atom on a silicon surface. Implications for the interpretation of surface photoelectron spectra are discussed.

Ligand field splitting on the xenon 4d core levels in XeFx (x = 2, 4, 6) compounds from high-resolution gas-phase photoelectron spectra: the structure of XeF6

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLigand field splitting on the xenon 4d core levels in XeFx (x = 2, 4, 6) compounds from high-resolution gas-phase photoelectron spectra: the structure of XeF6J. N. Cutler, G. M. Bancroft, J. D. Bozek, K. H. Tan, and G. J. SchrobilgenCite this: J. Am. Chem. Soc. 1991, 113, 24, 9125–9131Publication Date (Print):November 1, 1991Publication History Published online1 May 2002Published inissue 1 November 1991https://doi.org/10.1021/ja00024a015RIGHTS & PERMISSIONSArticle Views223Altmetric-Citations57LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (870 KB) Get e-Alerts Get e-Alerts

The Ionizations of C60 in the Gas Phase and in Thin Solid Films.

ABSTRACTThe high-resolution He I photoelectron spectrum of C60 in the gas phase is reported and compared with the photoelectron spectrum of C60as a thin film prepared by vapor deposition (one to three monolayers) on gold. The spectra show low valence ionization bands that are very sharp and well-separated for a molecule of this size, consistent with the highly symmetric truncated icosahedral structure and theoretical calculations. The total band widths of the valence ionizations from the thin film samples are comparable to those from the gas phase species, showing that the electronic interactions between the molecules and with the surface do not significantly influence these measurements of the molecular electronic structure. The gas phase photoelectron spectra also show vibrational fine structure in the first and second ionization bands with spacings that are consistent with the two totally symmetric vibrational modes of C60. The first vertical ionization energy relative to the vacuum level is determined to be 7.61 ± 0.02 eV from these gas phase measurements.

Multicentered Interactions in Carbonyl Bridged Dimers by UV-PE Spectroscopy and DV-Xα Quantum Mechanical Calculations

The electronic structure of (μ-CO) 2-[Rh(η 5-C 5R 5)] 2 ( I) and (μ-CO) 2- [Ni(μ 5-C 5H 5)] 2 ( II) (hereafter η 5-C 5H 5 = Cp; η 5-C 5R 5 = Cp', R = CH 3) has been accurately investigated carrying out first principle DV-Xα calculations. The theoretical data have been related to the He I and He II gas-phase photoelectron (PE) spectra adopting the transition state procedure. An excellent matching between theory and experiment has been found allowing a detailed assignment of all the PE exprerimental features. The relative intensity changes experimentally found on passing from the He I to the He II ionizing source are well in tune with the atomic compositions of the corresponding MOs.

High resolution molecular gas phase photoelectron spectra of core levels using synchrotron radiation - vibrational and ligand field splittings

A new high resolution photoelectron spectrometer designed for core level photoelectron studies of gas phase volatile and involatile compounds using synchrotron radiation is briefly described. Xenon NOO Auger spectral linewidths of 0.13 eV indicate that the electron resolution is < 0.05 eV. The Xe 4d photoelectron linewidth of ≈0.20 eV, for an inherent linewidth of ⩾ 0.13 eV, shows that the photon width is close to the theoretical 0.12 Å (0.09 eV at 94 eV). This resolution is sufficient to observe, for the first time, vibrational splitting of the Si 2p core level of SiH 4 and ligand field splitting of the Xe 4d core level of XeF 2.

Bonding in clusters. 11. Gas-phase photoelectron spectra of the 12-apex closo systems 1,12-B12H10(CO)2, 1,2- and 1,7-C2B10H12, and related main Group V and VI heteroboranes and -carboranes. The electronic structure of B12H122-

The He I and He II photoelectron spectra of 1,12-B 12 H 10 (CO) 2 and 1,2- and 1,7-C 2 B 10 H 12 are assigned in terms of correspondence of bands to BH bonding or cluster-localized orbitals. The experimental assignments are found to agree excellently with MNDO calculations on the molecules, which allows assignment of the cluster orbitals and ionizations in terms of Ston's theory of closo-boranes. Spectra of the related closo-heteroboranes 1,2-X(CH)B 10 H 10 (X=P,As,Sb, X 2 B 10 H 10 (X=As,Sb), and SeB 11 H 11 are found to be very similar, also agreeing with calculated results. The lone pairs of the heteroatoms are found to be localized in the valence s atomic orbital. An ordbital diagram for B 12 H 12 2− is extrapolated from these results, which shows it to be distinctly different from the smaller closo-borane anions

Variable energy photoelectron study of the valence levels of CF 3X (X = F, Cl, Br, I) compounds between 21 and 200 eV photon energies

The gas phase photoelectron spectra of CF 3Cl and CF 3Br have been obtained between 20 and 170 eV, while the spectra of CF 3I and CF 4 have been obtained between 100 and 170 eV and between 100 and 200 eV, respectively, using synchrotron radiation. Strong enhancements in the photoionization cross sections are observed near threshold in both CF 3Cl and CF 3Br. These observations are in good accord with a previous measurement on CF 3Br but are contradictory to a recent report on CF 3Cl which shows nearly all the valence level cross sections decrease monotonically with increasing photon energy. Features observed in the experimental cross sections were analyzed using minimal basis set ab initio and continuum MS Xα calculations. The results show that the cross section profiles are largely independent of the nature of the ligands. Low-energy resonant enhancements are assigned to excitations into antibonding-like orbitals, while the broad and weak structures at high kinetic energy are ascribed to scattering of the photoelectrons.

Photoelectron spectroscopy of biologically active molecules. XVI. Benzophenone derivatives

The interaction of a carbonyl group with two adjacent aromatic units is discussed. The outer valence electronic structure of compounds of general formula PhCOAr, where Ar is phenyl, substituted phenyl, furyl and thienyl, is determined from their gas phase photoelectron spectra. Particular attention is paid to biologically active derivatives of 2-amino-5-chlorobenzophenone.

A reassignment of the gas-phase photoelectron spectra of the actinide tetrahalides UF4, UCl4, ThF4 and ThCl4 by relativistic hartree-fock-slater calculations

Geometry optimization calculations have been performed for the actinide tetrahalides UF4, UCl4, ThF4 and ThCl4 using the relativistic Hartree-Fock-Slater method. These molecules are computed to have tetrahedral equilibrium geometries in their ground states. The uranium compounds, however, are found to have an open-shell ground state and could therefore exhibit a Jahn-Teller distortion away from tetrahedral symmetry. Assuming a tetrahedral geometry for these molecules, vertical ionization energies have been computed and this has led to a partial reassignment of the molecular gas-phase photoelectron spectra.

ChemInform Abstract: Electronic Structure and Twisted Intramolecular Charge Transfer in Dimethylanilines

The spectroscopically parameterized CNDO/S3 model is used to provide a quantitative description of the valence electron photoemission, ultraviolet absorption, and twisted intramolecular charge transfer fluorescence in N,N‐dimethylaniline, p‐cyano‐N,N‐dimethylaniline, and 3‐methyl‐4‐cyano‐N,N‐dimethylaniline. Additionally, the CNDO/S3 density of valence states was used to determine a twist angle of 30° for both N,N‐dimethylaniline and p‐cyano‐N,N‐dimethylaniline via the analysis of gas phase photoelectron spectra.

Electronic structure and twisted intramolecular charge transfer in dimethylanilines

The spectroscopically parameterized CNDO/S3 model is used to provide a quantitative description of the valence electron photoemission, ultraviolet absorption, and twisted intramolecular charge transfer fluorescence in N,N-dimethylaniline, p-cyano-N,N-dimethylaniline, and 3-methyl-4-cyano-N,N-dimethylaniline. Additionally, the CNDO/S3 density of valence states was used to determine a twist angle of 30° for both N,N-dimethylaniline and p-cyano-N,N-dimethylaniline via the analysis of gas phase photoelectron spectra.

A variable energy photoelectron study of the valence and Hg 5d levels of Hg(CH3)2

Using monochromatized synchrotron radiation, the gas phase photoelectron spectra of the Hg 5d and valence levels of Hg(CH3)2 have been obtained between 21 and 100 eV photon energies. Experimental valence band branching ratios have been compared with theoretical branching ratios from MS-Xα calculations. Our results strongly suggest that the ordering of valence levels is 2a″2&amp;lt;3a1&amp;lt;2e′&amp;lt;2e″, rather than 2a″2&amp;lt;3a1&amp;lt;2e″&amp;lt;2e′ from previous theoretical calculations. For the 3a′1 orbital, two shape resonances are predicted at 30 and 50 eV kinetic energy. Only the one at 30 eV is observed. Interchannel coupling with Hg 5d photoemission is important for the outermost 2a″2 and 3a′1 orbitals. Shape resonances and interchannel coupling strongly suggest that He ii:He i cross section ratios cannot generally be used to infer orbital character. The Hg 5d intensity ratio in Hg(CH3)2 differs from that of atomic Hg in the low photon energy region. This effect is probably due to the differences in the outgoing f wave potential between Hg and Hg(CH3)2.

Photoelectron spectroscopy of ƒ-element organometallic complexes: VII. Studies of di-cyclopentadienyluranium(IV) complexes containing tetrahydroborate, amido, pivalate and dithiocarbamate ligands

A study of gas phase photoelectron spectra of a series of U(η 5-C 5H 5) 2X 2 (X = BH 4, NEt 2 O 2CC(CH 3) 3, S 2CNEt 2) complexes has revealed changes in the sequence of upper filled molecular orbitals along the series. In all cases the first ionization event corresponds to removal of uranium 5ƒ electrons. In the case of X = NEt 2, the next highest occupied ligand-based MO is an almost pure N2 p lone pair, but in the other complexes this MO is π-ring in nature. The observations are consistent with the higher reactivity of the amido complexes toward molecules containing polar double bonds or acidic hydrogens and with the greater labilities of the UCp bonds in the other complexes.

A variable energy photoelectron study of the valence levels and I 4d core levels of CF3I

Using monochromatized synchrotron radiation, gas phase photoelectron spectra of CF3I have been obtained between 21 and 100 eV photon energies. Experimental valence band branching ratios have been compared with theoretical branching ratios from MS-Xα calculations. The generally good agreement between experiment and theory confirms the orbital assignment: 4e&amp;lt;4a1&amp;lt;1a2∼3e&amp;lt;2e&amp;lt;3a1&amp;lt;1e∼2a1 &amp;lt;1a1, in order of increasing binding energy. In contrast to CF4, MS-Xα calculations predict two shape resonances for CF3I at 15.2 eV (e channel) and 17.2 eV (a1 channel). Experimentally, weak shape resonances are observed on e orbitals at ∼14 eV kinetic energy. The cross sections are very useful for correlating orbitals in CF3I with those of CF4. For example, the cross sections suggest that the 3e orbital in CF3I correlates with the 1t1 orbital rather than the 4t2 orbital in CF4. After the onset of the I 4d level at ∼57 eV, intershell coupling becomes important in enhancing valence band levels having high I 5p character such as the 4e orbital. The I 4d branching ratio from 66 to 110 eV is similar to the Xe 4d branching ratio in atomic Xe, indicating atomic-like behavior for the I 4d subshell.

Photoelectron study of the valence level cross sections of XeF2 from 21 to 50 eV photon energy

Using monochromatized synchrotron radiation, the gas phase photoelectron spectra of the first five valence orbitals of XeF2 have been obtained from 21–50 eV photon energy. From these spectra, the branching ratios and partial cross sections have been calculated. Theoretical branching ratios and partial cross sections have been obtained from MS-Xα calculations and compared with experiment. The generally good agreement between experiment and theory confirms the DV-Xα and MS-Xα orbital assignments: 5πu &amp;lt;10σg &amp;lt;3πg &amp;lt;4πu &amp;lt;6σu, in order of increasing binding energy. Somewhat surprisingly because of the lack of antibonding virtual orbitals above threshold and the long Xe–F bond length (2.00 Å), a number of strong resonances are predicted and observed. For example, resonances are predicted at 4.8 (πg channel), 11.6 (πu, δu channels), and 14.3 eV (σu channel) kinetic energies. The observed resonance positions are usually in reasonable agreement with these. The nature of these resonances are discussed, and compared to similar features in O2, F2, and CO2.

Experimental characterization of an electron-rich (.sigma.2.pi.4.delta.2.delta.*2) metal-metal triple bond. Synthesis, reactivity, and photoelectron spectral studies of trimethylphosphine complexes of dirhenium(II)

The reaction of (n-Bu/sub 4/N)/sub 2/Re/sub 2/X/sub 8/ (X = Cl or Br) with PMe/sub 3/ gives high yields of the triply bonded complexes Re/sub 2/X/sub 4/(PMe/sub 3/)/sub 4/. These compounds are oxidized by NOPF/sub 6/ to give paramagnetic (Re/sub 2/X/sub 4/(PMe/sub 3/)/sub 4/)PF/sub 6/, and the chloro derivative reacts with Ph/sub 2/PCH/sub 2/PPh/sub 2/ (dppm) and Ph/sub 2/PNHPPh/sub 2/ (dppa) to give Re/sub 2/Cl/sub 4/(PMe/sub 3/)/sub 2/(dppm) and Re/sub 2/Cl/sub 4/(PMe/sub 3/)/sub 2/(dppa), respectively. NMR spectroscopy (/sup 1/H and /sup 31/P(/sup 1/H)) shows that the latter complexes possess fairly symmetrical structures in which the PMe/sub 3/ ligands are in cis dispositions with respect to the bridging dppm and dppa ligands. The volatility of Re/sub 2/Cl/sub 4/(PMe/sub 3/)/sub 4/ has permitted the measurement of its gas-phase photoelectron spectrum which accords with this compound possessing a sigma/sup 2/..pi../sup 4/delta/sup 2/delta*/sup 2/ configuration. The delta* ionization band is slightly narrower than the delta ionization band and occurs at about 0.9 eV lower binding energy. The ..pi.. ionization gives evidence of spin-orbit splitting as expected for the heavy-atom rhenium character. An ionization assigned to removal of an electron from the valence sigma orbital is observed at a binding energy 1 eV higher thanmore » the ..pi.. ionization. 42 references, 3 figures, 2 tables.« less

Photoelectron study of the valence levels of CF4 and SiF4 from 20 to 100 eV

Using monochromatized synchrotron radiation, the gas phase photoelectron spectra of the five valence orbitals of CF4 and SiF4 have been obtained from 21 to 100 eV photon energies. Branching ratios (BR) for both molecules, and partial cross sections (σ) for CF4, have been obtained from these spectra. The agreement between our σ values for CF4 and previous results is excellent. Theoretical branching ratios, partial cross sections, and β values have been obtained from MS Xα calculations, and compared with experiment. The generally good agreement between experiment and theory for SiF4 confirms the orbital assignment: 1t1&amp;lt;5t2&amp;lt;1e&amp;lt;4t2&amp;lt;5a1, in order of increasing binding energy. In contrast to the CF4 results which show little structure, five shape resonances are predicted for SiF4, at 3, 7, 13, 23, and 35 eV kinetic energies. The predicted resonance positions and intensities are in good agreement with experiment (e.g., for the 23 and 35 eV resonances), but the low energy resonance positions and intensities are usually not well reproduced experimentally. The radically different resonance features in CF4 and SiF4 are discussed.

Electronic structures of the closo-thiaboranes 1-SB9H9 and 1-SB11H11. Electrophilic substitution in 1-SB9H2

Comparison of the results of MNDO calculations for 1 -SB9H9 and the previously reported gas-phase photoelectron spectrum enables the cluster-bonding molecular orbitals to be assigned. The electronic structure of 1-SB9H9 is compared with those of [B10H10]2–, 1,10-B10H8(N2)2′ and 1,10-C2B8H10. The cluster bonding in these compounds is found to be very similar. The bonding in 1-SB11H11 is also analysed. Possible sites for the substitution of 1-SB9H9 by electrophiles X+(e.g. H+) are examined. The observed substitution patterns are rationalised on the basis of the calculated atomic charges and the composition of the highest filled molecular orbitals.

μ 3-S bonding mode in H 2M 3(CO) 9S clusters of Ru and Os. An UVPES and theoretical study

The electronic structure of H 2M 3(CO) 9S clusters (M = Ru, Os) is discussed on the basis of their He I and He II excited gas-phase photoelectron spectra and on the basis of CNDO quantum mechanical calculations. The PE data clearly demonstrate the cleavage of two direct MM interactions by operation of the bridging hydrides, giving rise to three-center two-electron MHM levels. The μ 3-S bonding mode has been described in detail and compared with previous results on related μ 3-CY cluster derivatives. The CNDO results on Ru 3(CO) 9S =, HRu 3(CO) 9S − and H 2Ru 3(CO) 9S indicate that the μ 3-S—cluster interaction is mostly independent of the presence of the bridging hydrides.