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  • 1
    Electronic Resource
    Electronic Resource
    Electronic structure of KxC60− in the gas phase (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4028-4031 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photoelectron spectra of KxC60− (x=1–3) have been studied in the gas phase, and the electron affinities obtained. These were found to decrease linearly with the number of K atoms. The result is consistent with an ionic description of the K–C60 chemical bonding, with each K atom donating its outer 4s electron to the t1u orbital of C60. Vibrational autodetachment from a weakly bound excited electronic state was discovered in KC60−, and a series of three equally spaced peaks were assigned to a progression in the intermolecular K–C60 stretching vibration with a frequency of 140 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461853
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  • 2
    Electronic Resource
    Electronic Resource
    Vibrational autodetachment spectroscopy of Au−6 : Image-charge-bound states of a gold ring (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 7515-7518 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Spectral experiments on mass-selected negative cluster ions of gold and silver were performed in the wavelength range near the threshold for one-photon photodetachment of the extra electron. The Au−6 cluster ion displayed a uniquely well resolved spectrum consisting of a progression in a single vibrational mode. Details of this threshold photodetachment spectrum and the associated photoelectron energy distribution suggest an explanation based on autodetachment from totally symmetric vibrational levels of very weakly bound excited electronic state (bound by image charge forces) of the Au−6 cluster in the form of a planar, six-fold symmetric, gold ring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459378
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  • 3
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy and electronic structure of clusters of the group V elements. I. Dimers (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6310-6317 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The HeI (584 A(ring)) high resolution photoelectron spectra of As+2, Sb+2, and Bi+2 have been obtained with a high temperature molecular beam source. A pure As2 beam was produced by evaporating Cu3As. Sb2 was generated as a mixture with the atoms and tetramers by evaporating the pure element, while Bi2 was generated as a mixture with only the atoms from the pure element. Vibrational structure was well resolved for the As+2 spectrum. Spectroscopic constants were derived and reported for the related ionic states. In addition, we have carried out relativistic complete active space self-consistent field followed by multireference single + double configuration interaction calculations on these dimers both for the neutral ground states and the related ionic states. The agreements between the calculated and experimentally derived spectroscopic constants were fairly good, although the calculations tended to underestimate consistently the strength of the bonding in these heavy homonuclear diatomics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459000
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  • 4
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy and electronic structure of clusters of the group V elements. II. Tetramers: Strong Jahn–Teller coupling in the tetrahedral 2E ground states of P+4, As+4, and Sb+4 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6318-6326 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution HeI (584 A(ring)) photoelectron spectra have been obtained for the tetrameric clusters of the group V elements: P4, As4, and Sb4. The spectra establish that the ground 2E states of tetrahedral P+4, As+4, and Sb+4 are unstable with respect to distortion in the ν2(e) vibrational coordinate. The E⊗e Jahn–Teller problem has been treated in detail, yielding simulated spectra to compare with experimental ones. Vibronic calculations, extended to second order (quadratic coupling) for P+4, account for vibrational structure which is partially resolved in its photoelectron spectrum. A Jahn–Teller stabilization energy of 0.65 eV is derived for P+4, which can be characterized in its ground vibronic state as being highly distorted, and highly fluxional. Linear-only Jahn–Teller coupling calculations performed for As+4 and Sb+4, show good qualitative agreement with experimental spectra, yielding stabilization energies of 0.84 and 1.4 eV, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459698
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  • 5
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy and electronic structure of clusters of the group V elements. III. Tetramers: The 2T2 and 2A1 excited states of P+4, As+4, and Sb+4 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6327-6333 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Methods employing high resolution HeI (584 A(ring)) photoelectron spectroscopy have been applied to the tetrameric clusters of the group V elements, to resolve details of vibronic and spin–orbit structure in the first three electronic states of P+4, As+4, and Sb+4. Measured spacings of distinct vibrational progressions in the ν1 mode for the 2A1 states of P+4 and As+4, yield vibrational frequencies of 577 (5) cm−1 for P+4 and 350 (6) cm−1 for As+4. Franck–Condon factor calculations suggest bond length changes for the ions in the 2A1 states of 0.054 (3) A(ring) for P+4 and 0.060 (3) A(ring) for As+4. Strong Jahn–Teller distortions in the ν2(e) vibrational mode dominate the structure of the 2E ground states of the tetrameric ions. Both Jahn–Teller and spin–orbit effects appear in the spectra of the 2T2 states of the tetrameric ions, with the spin–orbit effect being dominant in Sb+4 and the Jahn–Teller effect dominant in P+4. Vibrational structure is resolved in the P+4 spectrum, and the ν3(t2) mode is found to be the one principally active in the Jahn–Teller coupling. A classical metal-droplet model is found to fit well with trends in the IPs of the clusters as a function of size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458975
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  • 6
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy and electronic structure of heavy group IV–VI diatomics (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 899-908 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrationally resolved HeI (584 A(ring)) photoelectron spectra of the heavy group IV–VI diatomics SnSe, SnTe, PbSe, and PbTe were obtained with a new high temperature molecular beam source. Ionization potentials and spectroscopic constants are reported for all the ionic states observed. Relativistic complete active space multiconfiguration self-consistent field (MCSCF) followed by multireference singles+doubles relativistic configuration interaction (CI) calculations which included up to 200 000 configurations were made on both the neutral diatomics and their positive ions. Ionization potentials and spectroscopic constants were calculated and were in good agreement with the experimentally measured values. Relativistic CI potential energy curves were calculated for all the neutral ground states and the ionic states involved. Relativistic effects were shown to play an important role in these heavy diatomics. The 2Σ+1/2 and 2Π1/2 states for all four molecular ions showed avoided curve crossings, which resulted in pronounced shoulders in the Ω=1/2 potential energy curves of PbTe+. Experimentally, autoionization transitions were also observed for the PbTe+ spectrum. The importance of the relativistic effect and chemical bonding in the heavy diatomics are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458124
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  • 7
    Electronic Resource
    Electronic Resource
    Electronic structure and chemical bonding of the first row transition metal dichlorides, MnCl2, NiCl2, and ZnCl2: A high resolution photoelectron spectroscopic study (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 957-966 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: High resolution He i (584 A(ring)) photoelectron spectra of ZnCl2, MnCl2, and NiCl2 were measured using a high temperature supersonic molecular beam source. In ZnCl2, vibrational structures were resolved, and spectroscopic constants were derived for the observed molecular ion states. A single ν1 vibrational progression was observed for the C 2Σ+g state of ZnCl+2. A Franck–Condon factor calculation allowed us to obtain a Zn–Cl equilibrium bond length increase of 0.095(5) A(ring) and a ν1 vibrational frequency of 290(8) cm−1. For the open-shell molecules, MnCl2 and NiCl2, no vibrational structure could be resolved because of their very low bending frequencies. Transitions from the ligand orbital and metal d orbital ionizations were clearly resolved, with those of the d orbitals having considerably narrower band widths. Even though many final states are expected for ionization of the open-shell d orbitals, only a few states were observed. This was explained in MnCl2 by the one-electron spin selection rule: Sf=Si ±1/2. Besides the spin selection rule, a propensity toward high spin was proposed to account for the spectrum of NiCl2. From the metal d orbital and ligand orbital splittings, the degree of covalent bonding was inferred to be in the order of: MnCl2〉NiCl2〉ZnCl2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459122
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  • 8
    Electronic Resource
    Electronic Resource
    Photodetachment photoelectron spectroscopy of multiply charged anions using electrospray ionization (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1957-1966 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A magnetic-bottle time-of-flight (TOF) photoelectron spectrometer, coupled with an electrospray ionization source, has been developed for the investigation of multiply charged anions in the gas phase. Anions formed in the electrospray source are guided by a radio-frequency quadrupole ion guide into a quadrupole ion trap, where the ions are accumulated. A unique feature of this apparatus involves the coupling of a TOF mass spectrometer to the ion trap with perpendicular ion extraction. The ion trap significantly improves the duty cycle of the experiments and allows photodetachment experiments to be performed with low repetition-rate lasers (10–20 Hz). This novel combination makes the photodetachment photoelectron spectroscopy studies of multiply charged anions possible for the first time. Furthermore, the perpendicular extraction of ions, pulsed out of the ion trap, to the TOF mass spectrometer allows the ion energies to be conveniently referenced to ground, simplifying the configuration of the TOF mass spectrometer and the subsequent magnetic-bottle TOF photoelectron spectrometer. The mass resolution (M/ΔM) achieved is about 800 for smaller ions. The magnetic-bottle photoelectron spectrometer resolution is about 11 meV full width at half maximum for 0.5 eV photoelectrons with an overall resolution of ΔE/E∼2%. The detailed design, construction, and operation of the new apparatus are presented. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149694
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of lead, arsenic and mercury in cosmetic formulations at modified electrodes (1994)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of cosmetic science 16 (1994), S. 0 
    Details
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Lead, arsenic and mercury in cosmetic formulations digested with HNO3+ HF (10:3) or HNO3+ H2SO4 (5:1) in a microwave oven were determined, respectively, by the thin mercury film electrode, gold electrode and thin gold film electrode in sodium acetate buffer, in 6 m HNO3 and 0.1 m HCIO4 solution. Comparison with results obtained from atomic absorption spectrophotometric analysis (AAS) showed good agreement. The detection limits were 0.38 ppb (μgl-1), 0.66ppb and 0.04ppb for lead, arsenic and mercury, respectively, using square wave anodic stripping voltammetry. The detection limits for lead, arsenic and mercury were 0.53 ppb, 1.24ppb and 0.40ppb, respectively, using AAS. The two methods proposed were applicable to the determination of concentrations at ppb levels of commercial cosmetic formulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-2494.1994.tb00079.x
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  • 10
    Electronic Resource
    Electronic Resource
    Residual Oil Hydrodesulfurization Using Dispersed Catalysts in a Carbon-Packed Trickle Bed Flow Reactor (1995)
    s.l. : American Chemical Society
    Energy & fuels 9 (1995), S. 2-9 
    Details
    ISSN: 1520-5029
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ef00049a001
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