Intermolecular-interaction effects on quantum-phase and information-entropy dynamics of dimers interacting with a single-mode coherent field

Exciton recurrence motion in aggregate systems in the presence of quantized optical fields

The exciton dynamics of model aggregate systems, dimer, trimer, and pentamer, composed of two-state monomers is computationally investigated in the presence of three types of quantized optical fields, i.e., coherent, amplitude-squeezed, and phase-squeezed fields, in comparison with the case of classical laser fields. The constituent monomers are assumed to interact with each other by the dipole-dipole interaction, and the two-exciton model, which takes into account both the one- and two-exciton generations, is employed. As shown in previous studies, near-degenerate exciton states in the presence of a (near) resonant classical laser field create quantum superposition states and thus cause the spatial exciton recurrence motion after cutting the applied field. In contrast, continuously applied quantized optical fields turn out to induce similar exciton recurrence motions in the quiescent region between the collapse and revival behaviors of Rabi oscillation. The spatial features of exciton recurrence motions are shown to depend on the architecture of aggregates. It is also found that the coherent and amplitude-squeezed fields tend to induce longer-term exciton recurrence behavior than the phase-squeezed field. These features have a possibility for opening up a novel creation and control scheme of exciton recurrence motions in aggregate systems under the quantized optical fields.

Second harmonic generation from insoluble films of a rhodamine dye at the air-water interface: effect of sodium dodecylsulfate

The second harmonic generation (SHG) from the insoluble monolayers of bis-(N-ethyl, N-octadecyl)rhodamine perchlorate (RhC18) formed on the surface of sodium dodecylsulfate (SDS) solutions of different concentrations has been studied. An enhancement of the second harmonic response was observed in the mixed films of RhC18/SDS compared to the pure-dye layer. To clarify the origin of the phenomenon, the films were characterized by surface pressure-area isotherm and reflection-absorption spectroscopy studies. The analysis of surface pressure-area isotherms of RhC18/SDS layers showed that incorporated SDS molecules essentially influence the rheological properties of the dye monolayer. The film parameters, such as the molecular surface area, maximum surface pressure, and solid-condensed phase composition, are the functions of SDS bulk concentration. A joint analysis of the SHG results and the reflection-absorption spectra revealed that the structural ordering within films was responsible for the enhancement of the nonlinear optical response, whereas the contributions from the spectral shifts and increased absorption upon aggregate formation are of less importance.