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  • 1
    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
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  • 2
    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
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 957-966 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 899-908 
    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
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 201 (1993), S. 217-222 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 201 (1993), S. 212-216 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 158 (1989), S. 297-300 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 5269-5275 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Photoelectron spectra of rare gas dimers Ar2, Kr2, and Xe2 have been measured using the He i radiation at 584 A with a resolution of 13 meV. All the six ionic states in the He i region have been resolved for the first time, including some of the purely repulsive states. Ionization energies are presented to an accuracy ≤0.003 eV. Dissociation energies (D0) of the ionic states are calculated using the best estimate adiabatic ionization energies. The D 2Σ1/2g+ states of all the dimers are weakly bound, contrary to an earlier theoretical prediction. Part of the vibrational structure of two of the electronic states of Ar2 has been resolved. For the A 2Σ1/2u+ state, as many as 14 vibrational excitations are observed. These excitations are assigned to transitions to the higher vibrational levels of v=32–45. For the B 2Π3/2g state, three vibrational structures are resolved and are assigned to v=2–4 of the ionic state. Accurate values of the spectroscopic constants of these states are presented. The present values are compared with the values available in the literature. The De values for the A 2Σ1/2u+ and the B 2Π3/2g states are estimated to be 1.361 and 0.104 eV, respectively.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Electron Spectroscopy and Related Phenomena 51 (1990), S. 513-526 
    ISSN: 0368-2048
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1903-1911 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Migration and concentration levels of sodium dioctylsulfosuccinate (SDOSS) surfactant molecules in 50%/50% styrene/butyl acrylate latex were detected at the film-substrate (F-S) and film-air (F-A) interfaces in mono- and double-layered films. For the purpose of quantitative analysis, absorption coefficients of the 1,056 and 1,046 cm-1 bands attributed to the SO3-Na+…HOOC and SO-3Na+…H2O associations, respectively, were determined. Using group theory formalism, local geometries of the SO-3Na+ hydrophilic groups of SDOSS can be predicted. The analysis is extended to the 1,261 and 1,209 cm-1 bands resulting from the S - O asymmetric stretching vibrations, due to the same SO-3Na+ … HOOC and SO-3Na+ … H2O associations, and to the 1,290 and 1,236 cm-1 bands, due to asymmetric stretching modes of hydrophobic tails of the SDOSS. By the use of polarization attenuated total reflectance Fourier transform infrared (ATRFT-IR) experiments, these studies show that hydrophilic SO-3Na+ ends on SDOSS are preferentially parallel to the film surface. At the same time, hydrophobic tails are perpendicular to the surface. The assessment of the amounts of SDOSS at the F-S and F-A interfaces was obtained by quantitative ATR FTIR analysis, which was extended to the silicone-modified double-layer latex films. In this case, the concentration of SDOSS molecules decreases as the depth of penetration increases. The highest concentrations of SDOSS molecules are detected at the shallowest depths near the surface of the top layer and the interfacial regions between the latex layers. © 1996 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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