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  • 1
    Electronic Resource
    Electronic Resource
    Model studies for rovibronic IVR with applications to benzene (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 249-259 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Intramolecular vibrational energy redistribution (IVR) is treated. Nearly isoenergetic rigid-rotor harmonic-oscillator states are rovibronically coupled by the interplay of anharmonic and Coriolis forces. The theory predicts linewidth distributions of rovibronic states and explains the selective supression of rotational spectral lines. Applications to sub-Doppler spectra of the 1410120 band of benzene allow to extract values for effective intramolecular interactions. These results are supported by direct calculations based on the force field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453622
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  • 2
    Electronic Resource
    Electronic Resource
    A unified theory of electron transfer and internal conversion based on solitary electronic states (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 354-365 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A description of electron transfer processes is presented which makes use of the concept of solitary states for the construction of the initial and the final state wave functions. Even though this concept is closely related to an adiabatic description in the sense that it provides partial delocalization of these states it also assures localization for a symmetric donor–acceptor system. The theory can be applied to arbitrary values of the internal parameters characterizing the system, that is the electronic donor–acceptor coupling V, the free energy change ΔE, and the coupling of the electron to nuclear motions represented by a Stokes shift S. This way the theory of nonadiabatic electron transfer processes is put on equal footing with the theory of adiabatic transitions and even more interestingly the same concept unifies the common electron transfer theory and the theory of internal conversion processes if ||ΔE|| and (or) ||V|| exceed S. It is shown analytically how the results of the conventional treatments for adiabatic, nonadiabatic, and internal conversion processes fall out of this theory as special cases. It is further examplified how the system develops from the so-called normal regime with ||ΔE||〈S into the inverted regime with ||ΔE||〉S as function of ΔE for fixed parameters of V and S and as function of V for fixed parameters of ΔE and S.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456481
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  • 3
    Electronic Resource
    Electronic Resource
    Picosecond energy transfer of vibrationally hot molecules in solution: Experimental studies and theoretical analysis (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4094-4101 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The cooling of vibrationally hot azulene is studied in different solvents by picosecond spectroscopy. Excitation to the electronic S1 state generates molecules with a vibrationally hot ground state by rapid internal conversion. The subsequent cooling is monitored by the temperature-dependent change of the S0–S1 absorption edge and occurs via interaction with the solvent on a time scale of several tens of picoseconds. A theoretical model of intermolecular energy transfer in the liquid phase is developed. The vibrational excess energy of azulene is transferred to the solvent molecules by isolated binary collisions, where the multimode vibrational system of the molecules is considered explicitly. The dissipation of energy within the solvent is simulated by the macroscopic conduction of heat. The temporal development of the vibrational temperature of the azulene molecules and the concommitant changes of absorption are calculated taking into account the properties of the specific solvent. The results of the theory show quantitative agreement with our data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458741
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  • 4
    Electronic Resource
    Electronic Resource
    Reply to "Comment on: ‘Cytochrome oxidation in bacterial photosynthesis' '' (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 3394-3395 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454906
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  • 5
    Electronic Resource
    Electronic Resource
    Structural investigations of GaN grown by low-pressure chemical vapor deposition on 6H–SiC and Al2O3 from GaCl3 and NH3 (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1890-1895 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN films grown on (0001) 6H–SiC and (0001) Al2O3 substrates using low-pressure chemical vapor deposition with GaCl3 and NH3 as precursors are comparatively explored by optical, scanning tunneling, and transmission electron microscopy. Independent of the substrate material used, the surface of the GaN layers is covered by hexagonally shaped islands. For GaN on 6H–SiC, the islands are larger in diameter ((approximate)50 μm) and rather uniformly distributed. An atomically flat interface is observed for GaN on Al2O3 in contrast to GaN grown on 6H–SiC, where the interface is characterized by large steps. For both substrates, faceted holes (named as pinholes) are observed in near-surface regions of the GaN layers occurring with a density of about 7×108 cm−2. No unequivocal correlation between the density of pinholes and the density of threading dislocations ((approximate)1.6×1010 cm−2 for GaN/Al2O3 and (approximate)4×109 cm−2 for GaN/6H–SiC) can be found. Rather, different types of defects are identified to be correlated with the pinholes, implying a dislocation-independent mechanism for the pinhole formation. Despite the small lattice mismatch between GaN and 6H–SiC, the pronounced original surface roughness of this substrate material is believed to account for both the marked interfacial roughness and the still existing high density of threading dislocations. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365994
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  • 6
    Electronic Resource
    Electronic Resource
    Long-lived InGaAs quantum well lasers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1861-1862 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pseudomorphic InGaAs lasers with cw operating lifetimes exceeding 5000 h are reported for the first time. The device structure, grown by low-pressure metalorganic chemical vapor deposition, incorporates a single In0.37Ga0.63As strained-layer quantum well in a GaAs/AlGaAs graded-index separate confinement heterostructure. These devices are remarkable for their immunity to sudden failure and for their (gradual) degradation rates which are comparable to the best GaAs lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101260
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  • 7
    Electronic Resource
    Electronic Resource
    Spectroscopic studies of charge-transfer complexes of diazabenzenes with iodine (1976)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 80 (1976), S. 1809-1811 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100557a014
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  • 8
    Electronic Resource
    Electronic Resource
    On p-type doping in GaN—acceptor binding energies (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1298-1300 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence investigations on undoped n-type GaN layers grown on 6H-SiC and sapphire reveal the presence of residual acceptors with a binding energy of 230 meV. Their presence in high temperature vapor phase epitaxy grown layers is strongly correlated with the graphite susceptor containing the Ga. Mg as a contamination can be ruled out. In metal organic vapor phase epitaxially grown layers, the metal organic are probably the source of the carbon contamination. It is concluded that carbon on nitrogen sites introduces the most shallow acceptor in GaN. The experimental observations are supported by an estimate of the acceptor binding energy using effective-mass-theory. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114403
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  • 9
    Electronic Resource
    Electronic Resource
    Strongly localized excitons in gallium nitride (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2556-2558 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on strong excitonic luminescence in wurtzite GaN at 3.309 and 3.365 eV (T=6 K). These lines lie well below the band gap and are found commonly in layers grown by different techniques and on different substrates. From detailed photoluminescence investigations we find small thermal activation energies and a very weak electron–phonon coupling. The photoluminescence behavior under hydrostatic pressure is indicative of strongly localized defects. These findings are similar to observations of excitons localized at extended defects such as dislocations in II–VI compounds. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116182
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  • 10
    Electronic Resource
    Electronic Resource
    Properties of GaN grown at high rates on sapphire and on 6H–SiC (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2716-2718 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thick GaN films were deposited with growth rates as high as 250 μm/h by the direct reaction of ammonia and gallium vapor at 1240 °C. The characteristics of our films are comparable to those of typical thin films grown by metal organic chemical vapor deposition or molecular beam epitaxy. Grown under identical conditions, films on (0001) sapphire and on (0001) 6H–SiC were compared in terms of their structural and optical properties. Considering x-ray rocking curve full width at half-maximum (FWHM: 420 arcsec), photoluminescence linewidths of the excitons (FWHM: 3 meV at 6 K and 100 meV at 300 K), free electron concentration, defect related luminescence, and the homogeneity of these properties, we find superior values for films grown on SiC. For both substrate materials we find an optimum growth rate window of 40–80 μm/h. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117688
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