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Notes: A new approach to locally design a control pulse is proposed. This locally optimized control pulse is explicitly derived, starting with optimal control formalism, and satisfies the necessary condition for a solution to the optimal control problem. Our method requires a known function, g(t), a priori, which gives one of the possible paths within the functional space of the objective functional. A special choice of g(t)≡0 reduces the expression of the control pulse to that derived by Kosloff et al. For numerical application, we restrict ourselves to this special case; however, by combining an appropriate choice of the target operator together with the backward time-propagation technique, we apply the local control method to population inversion and to wave packet shaping. As an illustrative example, we adopt a two-electronic-surface model with displaced harmonic potentials and that with displaced Morse potentials. It is shown that our scheme successfully controls the wave packet dynamics and that it can be a convenient alternative to the optimal control method for wave packet shaping. © 1998 American Institute of Physics.

Notes: Bath-induced coherence transfer effects on a time- and frequency-resolved resonant light scattering spectrum is theoretically investigated using the Markoff master equation. According to Eberly and Wódkiewicz, a general expression for an experimentally observable spectrum in terms of a molecular response function is derived within the density matrix formalism. To generalize our previous results of the bath-induced coherence transfer which were derived based on a displaced harmonic oscillator model [Y. Ohtsuki and Y. Fujimura, J. Chem. Phys. 91, 3903 (1989)], an eigenstate basis is used to represent a relevant system for investigating characteristics of the transfer. By the present model, we clarify the dependence of the bath-induced coherence transfer on the energy-level structure of the intermediate states associated with the transfer, i.e., energy mismatch effects. It is shown that if the energy mismatch of these states is smaller than dephasing rates, the bath-induced coherence transfer occurs resonantly. In the other cases, the energy mismatch brings about a modulation in the time evolution of the superposition state created by the bath-induced coherence transfer, which strongly diminishes the efficiency of the transfer. The resonance condition is derived analytically and is confirmed by numerical calculations of quantum beats induced by the bath-induced coherence transfer. The possibility of very rapid dephasing of a quantum beat signal which cannot be explained in terms of dephasing rates is also shown, when the transition moments have such values that give π-phase-shifted quantum beats in bath-induced fluorescence. © 1996 American Institute of Physics.

Notes: We present a method for the design of laser fields to control a selective preparation of enantiomers from their racemate. An expression for two components of the laser pulses [EX(t) and EY(t)] propagating along the Z axis is derived using a locally optimized control theory in the density operator formalism. This expression was applied to a selective preparation of (R-, L-) enantiomers from preoriented phosphinotioic acid (H2POSH) at low temperatures. The target operator was set for the populations to be localized in one side of the double-well potential. First, a simple one-dimensional model was treated. Then, a two-dimensional model in which a free rotation around the preoriented torsional axis is included was briefly considered. In the one-dimensional model, almost complete preparation of the enantiomers was obtained. The optimal electric field consists of a sequence of two linearly polarized pulses with the same phases but with different magnitudes. This means that the resultant electric field is linearly polarized with the polarization for obtaining the R-form nearly parallel to its S–H bond. The optimal electric field transfers the L-form into the R-form while suppressing the reverse process. In the two-dimensional model, the enantiomer selective preparation is controlled by a sequence of circularly polarized pulses. © 2001 American Institute of Physics.

Notes: Expressions for the differential cross section of the resonance Raman scattering from molecules in which initially prepared nonequilibrium vibronic levels undergo vibrational and/or electronic relaxations are derived by using the generating function method. Two kinds of the initial nonequilibrium vibronic distributions, single vibronic level and Poisson ones are taken into account. A displaced harmonic oscillator model for the initial and resonant vibrational states and a linear vibrational quantum number dependence of the relaxation constants are adopted in deriving the cross sections. Model calculations of the time-resolved resonance Raman scattering cross sections and of the excitation profiles of the nth order Stokes and anti-Stokes Raman bands are performed by using the derived expressions. The results of the calculation indicate that the anti-Stokes Raman bands make a significant contribution to the resonance Raman scattering from the nonequilibrium vibronic distributions. It is suggested that measurements of the excitation profiles are useful for analyzing the nonequilibrium distribution initially prepared and the subsequent relaxation mechanism.

Notes: Renormalization effects of the bath-induced vibronic population transfer on resonant light scattering (RLS) from molecules in condensed phases are theoretically studied based on the Markoffian master equation approach. By using the double space diagram technique, the self-energy originated from the bath-induced vibronic population transfer is analytically solved, and the analytic expressions for the intensities both of the stationary and of the time-resolved RLS spectra are derived. The renormalization effect is analyzed in terms of dimensionless molecular parameters, and model calculations are also performed to confirm theoretical results.

Notes: Effects of vibronic coherence transfer induced by the heat bath on ultrafast time-resolved resonant light scattering (RLS) spectra are theoretically investigated within the master equation approach. The vibronic coherence initially created by a coherent optical excitation transfers to other vibronic coherent states due to inelastic interactions between the vibronic system concerned (the relevant system) and the heat bath. The vibronic coherence transfer results in the quantum beats in the time-resolved RLS spectra. The bath-induced vibronic transition operator is derived in the double space representation of the density matrix theory. Model calculations of the femtosecond (fs) time-resolved RLS spectra are performed to demonstrate the effects of the bath-induced vibronic coherence transfer.

Notes: A theory of the emission spectrum from a multilevel molecular system pumped by strong resonant radiation fields based on the double space theory of the density matrix is developed. We are especially concerned with a three-level, one-laser system, and a three-level, two-laser system. It is shown that the band structure cannot always be estimated by the energy level structure of the dressed states. In fact, in both model systems, triplet structures of the emission spectra can be observed in the case where the magnitude of the molecule-field interaction is larger than that of the detuning. The characteristic features of the band structure are interpreted in terms of the dressed state picture based on analytically solvable models. Several numerical calculations are performed to show how the multiplet band structure in the emission spectrum is influenced by the detuning and the power of the pump field(s).

Notes: Laser-induced vibrational predesorption of molecules physisorbed on insulating substrates is theoretically investigated based on the Markoff master equation. The system vibrations, which consist of intramolecular vibrations of an admolecule and admolecule-surface vibrations, are divided by the adiabatic approximation, whereby the predesorption is represented by the nonadiabatic transitions from the bound states to the desorption continuum. By using the projection operator in the double(Liouville)-space representation, the bound-continuum couplings due to the nonadiabatic and the optical interactions are explicitly included in the master equation. The adiabatic theory is applied to CO physisorbed on a NaCl(100) surface, in which CO stretching and CO-surface vibration are chosen as the system vibrations. This two-dimensional model with a shallow Morse potential for the CO-surface potential gives a desorption rate of ∼10−4 s−1, which agrees with the experimentally measured rate by Chang and Ewing [Chem. Phys. 139, 55 (1989) and Phys. Rev. Lett. 65, 2125 (1990)]. The rate equations explicitly derived from the master equation are used to analyze the desorption dynamics. It is shown that predesorption is considerably enhanced by the incoherent phonon-assisted predesorption mechanism, i.e., by thermal excitation of the CO-surface stretching in the manifold of the excited CO stretching. Excitation by a single laser is extended to the two-laser excitation scheme to accelerate the predesorption. © 1997 American Institute of Physics.

Notes: Summary  Background The most characteristic change in psoriasis vulgaris is markedly increased, persistent keratinocyte proliferation. The underlying mechanism of excessive epidermal growth is controversial. We previously found and reported that T-cadherin was expressed in keratinocytes and confined to the basal layer of mouse and human skin. Invasive cutaneous squamous cell carcinoma showed a loss of T-cadherin expression. Another study showed that T-cadherin was a negative growth regulator of epidermal growth factor in T-cadherin transfectant neuroblastoma cells.Objectives  To obtain insight into the role of T-cadherin in keratinocyte proliferation and to investigate further the pathogenesis of psoriasis vulgaris, we examined the expression of T-cadherin, as well as E- and P-cadherin, in psoriasis vulgaris.Methods  Four untreated active psoriatic skin samples from psoriasis vulgaris patients and four normal human skin samples from plastic surgery were collected, cryosectioned and immunohistochemically stained by antihuman T-, P- and E-cadherin antibodies. Further, the immunofluorescence intensities of T- and P-cadherin on the basal layer of the epidermis were quantitatively measured by the histogram function of LSM 510 software installed in a Zeiss laser scanning confocal microscope. The data were statistically analysed by Student's t-test.Results  It was observed that T-cadherin was weakly and discontinuously expressed on the basal layer of psoriatic skin, while it was intensively expressed on all basal keratinocytes in normal human skin. In contrast, P-cadherin was strongly expressed throughout the entire epidermal layer in psoriatic skin samples, although its expression is restricted to the basal cell layer in normal human skin. There were no obvious differences in E-cadherin expression between normal human skin and psoriatic skin. Statistical analyses showed that the immunofluorescence intensity of T-cadherin in the basal cell layer of psoriatic skin (35 ± 9·08) was significantly decreased compared with that in normal human skin (131·75 ± 3·49, P = 2·46 × 10−6). There was a significant increase (P = 0·00139) in the immunofluorescence intensity of P-cadherin in the basal layer of psoriatic skin (68·25 ± 12·13) compared with normal human skin (26 ± 4·90).Conclusions  The present study demonstrates that there is downregulation of T-cadherin expression and upregulation of P-cadherin expression in psoriatic skin, which are considered to be involved in the hyperproliferation of keratinocytes in psoriasis vulgaris.