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  • 1
    Electronic Resource
    Electronic Resource
    Far-infrared spectra of diatomic polar molecules in simple liquids: Accounting for the anisotropic interaction (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 5323-5334 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A theoretical expression giving the far-infrared spectrum of a dilute solution of diatomic polar molecules in a nonpolar liquid solvent is derived in order to analyze the influence on this spectrum from the J=1 and J=2 components of the Legendre polynomial expansion of the anisotropic solute–solvent potential. A non-Markovian spectral theory incorporating finite correlation of the interaction, mixing effects between rotational lines and quantum intermolecular potential correlation functions is used. This theory allows one to analyze the influence of each anisotropic part of the interaction in terms of a very reduced set of parameters: the strength and the width of its time correlation function. The zero and finite frequency components of the J=2 contribution are also studied. In particular, we show that the use of quantum potential correlation functions gives a zero frequency component not only in the width, but also in the shift of the different rotational lines. Numerical results for DCl, HCl, and HF in SF6 liquid at 273 K are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463792
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  • 2
    Electronic Resource
    Electronic Resource
    Memory kernel for a multilevel quantum system driven by colored thermal noise (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 8939-8944 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The memory kernel appearing in a non-Markovian population equation for a multilevel quantum system stochastically coupled to a colored Gaussian bath is calculated on the basis of a fully quantum-mechanical treatment to construct the time autocorrelation function (TAF) associated to the system–bath interaction Hamiltonian. The limiting cases of high and low temperatures and white noise bath are also analyzed. These examples allow us to discuss in a very simple way the dependence of the memory kernel on the Bohr frequencies of the system, the intensity of the system–bath interaction, its correlation time, and the bath temperature. In particular, it is shown that a true Markovian population equation is only achieved at high temperatures with a bath correlation time much shorter than the relaxation process characteristic time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459232
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  • 3
    Electronic Resource
    Electronic Resource
    Infrared spectra of diatomic polar molecules in rare-gas liquids. I. Spectral theory (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3435-3442 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A theoretical model for the infrared (0–1) band of dilute solutions of diatomic polar molecules in nonpolar rare-gas liquids is presented. The model is based on decomposition of the rotational motion of the diatomic molecule into two limiting cases, according to the Bratos model: quasifree rotation and rotational diffusion. Contribution to the infrared absorption coefficient due to quasifree rotation is analyzed within a non-Markovian formalism using a stochastic directing intermolecular field (DIF) model to describe the diatomic molecule–solvent interaction. The P and R branches appear as a consequence of the quasifree contribution, which is also important in the Q-branch region. The contribution due to rotational diffusion is calculated making use of the Debye model and is mainly significant in the Q-branch region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456918
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  • 4
    Electronic Resource
    Electronic Resource
    Infrared spectra of diatomic polar molecules in rare-gas liquids. II. Application to the HCl in Ar, Kr, and Xe solutions (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3443-3449 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In paper I (the preceding paper), a spectral theory describing the near infrared fundamental band spectra of diatomic polar molecules impurities in nonpolar solvents has been developed in terms of a reduced set of parameters. In this paper, this spectral theory is applied to HCl in Ar, Kr, and Xe liquid solutions. The parameters obtained by fitting the experimental and calculated profiles are in good agreement with those calculated using several microscopic theories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456872
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  • 5
    Electronic Resource
    Electronic Resource
    Erratum: Far-infrared spectra of diatomic polar molecules in simple liquids: Accounting for the anisotropic interaction [J. Chem. Phys. 97, 5323 (1992)] (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2281-2281 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466233
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  • 6
    Electronic Resource
    Electronic Resource
    Optimum performance of a regenerative Brayton thermal cycle (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 2735-2741 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optimum performance of a regenerative Brayton cycle was analyzed. The model includes external and internal irreversibilities coming from four main sources: coupling to external heat reservoirs, turbine and compressor nonisentropic processes, pressure losses in the heater and the cooler, and the regenerator. In terms of the parameters accounting for each type of irreversibility, explicit numerical results are presented for the maximum efficiency, maximum power output, efficiency at maximum power output, power output at maximum efficiency, as well as for the pressure ratios required for maximum efficiency and maximum power. This analysis could provide a general theoretical tool for the optimal design and operation of real regenerative gas turbine power plants. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366104
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  • 7
    Electronic Resource
    Electronic Resource
    Irreversible refrigerators under per-unit-time coefficient of performance optimization (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1130-1132 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A finite-time thermodynamics analysis is used to investigate the optimal coefficient of performance (COP) of an irreversible Carnot refrigerator using the per-unit-time COP as an objective function for optimization. The model includes finite-rate heat transfers between the refrigerant and the external heat reservoirs, heat leak between heat reservoirs, and internal dissipations of the refrigerant. Heat conductances associated with heat transfers are optimized by maximizing the cooling power per unit of capital invested in the refrigerator. The obtained results are consistent with performance data for real low-temperature refrigerators. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120437
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  • 8
    Electronic Resource
    Electronic Resource
    Irreversible Carnot cycle under per-unit-time efficiency optimization (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 853-855 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Carnot-like irreversible power cycle is analyzed under maximum per-unit-time efficiency conditions. The model includes finite-rate heat transfers between the working fluid and the external heat reservoirs, heat leak between heat reservoirs, and internal dissipations of the working fluid. We present the results for the optimum distribution of the external and internal thermal heat conductances and the optimum area allocation ratio in terms of a dimensionless price parameter, the engine temperature ratio, and the internal irreversibility factor. The calculated optimized efficiencies agree with observed values for real power plants. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122023
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  • 9
    Electronic Resource
    Electronic Resource
    Far-infrared spectra of HCl in dense Ar and time-dependent anisotropic potential autocorrelation functions. A molecular dynamics study (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 252-261 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In many spectral theories, the knowledge of the time autocorrelation functions associated with the solute–solvent intermolecular anisotropic potential is a necessary step to obtain the far-infrared (FIR) spectra of small polar diatomic molecules dissolved in a nonpolar solvent. Within the pairwise additive approximation, we have obtained these functions from a molecular dynamics simulation for HCl in fluid Ar (between 100 and 480 amagat) at T=162.5 K. The simulated correlation functions are tested in the calculation of the pure far-infrared spectrum, appropriately described by a theory incorporating memory effects, line mixing effects, and the influence of any anisotropy order on the diatom–atom intermolecular potential. The comparison between the theoretical and experimental spectra allow us to obtain some conclusions about the relative importance of the first and second order anisotropic interaction correlations on the FIR spectra of HCl in dense Ar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466994
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  • 10
    Electronic Resource
    Electronic Resource
    Far-infrared permanent and induced dipole absorption of diatomic molecules in rare-gas fluids. I. Spectral theory (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 9161-9174 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a spectral theory for the far-infrared absorption spectrum of a very diluted solution of diatomic molecules in a rare-gas fluid, that includes permanent and induced contributions. The absorption coefficient is given as the convolution of a translational spectrum and a rotational spectrum. The former is described in terms of time correlation functions associated to the induced dipole moment. The latter is discussed on the basis of a model consisting of a quantum rigid rotor interacting with a thermal bath, making use of time correlation functions associated to the different anisotropic orders of the solute–solvent intermolecular potential. Non-Markovian and line mixing effects are taken into account. Explicit expressions for the five leading contributions of the induced dipole moment are given. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470027
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