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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 4 (1965), S. 330-333 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    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 105 (1996), S. 3883-3891 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The energies and dispersions of the image states and quantum well electronic states in layers of Xe and Kr on a Ag(111) substrate were determined by angle-resolved two-photon photoemission (ARTPPE). For Xe, we measured binding energies of unoccupied electronic states for 1–9 layers and their parallel dispersion out to 4 layers. We measured the binding energies for a monolayer of Kr and dispersions for one and two layers. The n=2 and n=3 image states of the bare metal evolve into quantum well states of the layer (states of the Xe conduction band discretized by the boundary conditions of a 2-D slab) at higher Xe thicknesses, where the n=2,3 states exhibit both a perpendicular and parallel dispersion similar to that of the bulk Xe conduction band. The n=1 state appears to evolve with coverage as an image state screened by the Xe layer, with appreciable electron density in the vacuum. A continuum dielectric model (modified image state picture) reproduces the gross trends in the data, while an explicit quantum well analysis is used to extract the bulk Xe conduction band dispersion. A simple model which takes into account the band structures of the substrate and the overlayer, as well as the image potential, gives good agreement with the binding energy data. The combination of high energy and momentum resolution along both the surface parallel and surface normal yields very precise measurements of the bulk Xe conduction band as well as information about the behavior of conduction band electrons at interfaces. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 7 (1968), S. 2140-2144 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 4024-4032 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study of the photodissociation dynamics of Mn2(CO)10 and the vibrational relaxation of its subsequent photoproducts in solutions has been carried out using picosecond time-resolved laser techniques. The molecule predissociates in less than 2–3 ps after excitation with a 295 nm photon. Two dissociation channels are open for this excitation wavelength, namely, the Mn–Mn bond breaking and the Mn–CO bond breaking, generating internally hot ⋅Mn(CO)5 and Mn2(CO)9, respectively. These two species have a different absorption spectrum in the visible region and are probed independently by varying the probe laser wavelength. The vibrational relaxation of these nascent photoproducts is observed for the first time. In cyclohexane the vibrationally hot Mn2(CO)9 reaches thermal equilibrium with the solvent through two distinct decay channels with time constants of 15 and 170 ps, respectively. The vibrationally cold Mn2(CO)9 then persists for many nanoseconds. The vibrational relaxation is found to be faster in the 2-propanol solution with time constants of 10 and 145 ps. On the other hand, the ⋅Mn(CO)5 species cools down in less than 10 ps and then exists in the solution for many nanoseconds as well. This result indicates that energy transfer from the internally hot ⋅Mn(CO)5 species to the solvent is much faster than from Mn2(CO)9. Comparison is made with Cr(CO)5 in similar solvents.
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  • 6
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A method is presented for numerical integration of the generalized Langevin equation (GLE) based on modeling of the "random force'' as a discrete autoregressive process. This modeling procedure, drawn from digital signal processing and spectral estimation methods which have been used extensively in electrical engineering applications, provides for efficient evaluation of the friction integral in the GLE as well as for generation of a random force process with the desired spectrum. The method is shown, through comparison with molecular dynamics results, to be effective in simulating the force autocorrelation function of an iodine atom dissolved in Lennard-Jones (LJ) xenon. In a companion paper this method is applied in a simulation of the vibrational relaxation of I2 in LJ xenon at two very different densities and found to perform well.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Results are presented which clarify the time scales for predissociation and geminate recombination in the iodine photodissociation/recombination reaction. Direct comparison of absorption features following A state excitation with those following B state excitation suggests that predissociation may be much more rapid (≤1 ps) than previously thought, and that geminate recombination is also very rapid (≤2 ps). Both of these results lead to the conclusion that curve crossing in solution is extremely facile and not the rate-limiting step in recombination. An important consequence of this is that molecular dynamics simulations seem to give reasonable results for recombination dynamics even when curve crossing is treated by oversimplified models. Finally, it is shown that in order to properly interpret the early time bleach kinetics it is necessary to consider dynamics within the ground state population remaining after excitation as well as excited state dynamics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The nonradiative decay dynamics of crystal violet, and other triphenyl-methane dyes, dissolved in a variety of solvents, are studied as a function of temperature. A linear viscosity dependence of the excited state absorption decay time in n-alcohol solvents is found at several constant temperatures. The temperature dependence at constant viscosity is anomalously negative over the entire viscosity range (0.6 to 8.0 cP) of these experiments. Various possible mechanisms for the observed behavior are critically discussed. Two color excite-and-probe studies reveal ground state bleach recovery times which are independent of excitation wavelength but strongly dependent on probe wavelength. The faster decay on the red side of the ground state absorption is shown to be the result of stimulated emission rather than the influence of a second state.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The fluorescence decays from submonolayers of pyrene separated from Si(111) by Xe spacer layers are measured as a function of spacer thickness (17–200 A(ring)), pyrene coverage, and emission wavelength. The results are explained in terms of two decay channels: energy transfer and trapping among the molecules in the two-dimensional pyrene overlayer, and excitation of electrons from the valence to the conduction band in the Si(111) by the dipole near field of the electronically excited pyrene molecule. The intralayer energy transfer is modeled using the Kohlrausch equation N(t)=N0 exp(−t/τ)α, in which α is related to the distribution of pyrene molecules in energy. Energy transfer from the molecule to the semiconductor is modeled using the classical image dipole theory. The classical model is used to calculate the energy transfer rates from a dipole to Si and GaAs as a function of dipole–semiconductor separation, and as a function of dipole emission wavelength.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 5433-5440 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The theoretical predictions of three theories for large amplitude dynamics on a barrierless excited state potential are tested. The predicted forms for the time dependent integrated excited state population are compared with experimentally measured excited state absorption decays of crystal violet in various solvents. We have generalized the early theory of Oster–Nishijima [J. Am. Chem. Soc. 78, 1581 (1956)] to allow for arbitrary placement of the initial excited state population relative of the nonradiative sinks which couple the flat excited state potential to the ground state. An analytic form for decay of the integrated excited state population is derived for this generalized flat potential model. In addition we have found that the predictions of Forster–Hoffmann [Z. Phys. Chem. NF 75, 63 (1971)] cannot be made to fit the experimentally measured excited state decays of crystal violet. Finally we show that the theory of Bagchi–Fleming–Oxtoby [J. Chem. Phys. 78, 7375 (1983)] can fit the decays observed in various solvents fairly well. The best fits, however, are obtained using the generalized flat potential model.
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