Collision broadening model for the biexciton resonance in CuCl

It is shown that the cage model of the spectral broadening of the biexciton resonance in CuCl due to collisions is in agreement with experimental results.     

The acoustic performance of building façades in hot climates: Part 1—Courtyards

The acoustic performance of perforated screens of unusual geometry was investigated by means of model work and computer simulation resulting from diffraction theory in which the barrier produces an amplitude gradient (thnadner) or a phase gradient (splitter). The results indicate that the protection obtained is similar to that of a solid thin barrier of equal height for a wide range of frequencies when the receiver is near the barrier. The thnadner and splitter screens were then examined, by means of one-tenth scale models, as a part of a courtyard. The results show that a considerable reduction in traffic noise is achieved which is again of the same order as that of a courtyard with a solid wall.     

An adaptation of the lattice gas to the water problem. II. Second-order approximation

The adaptation of the lattice-gas model to embody features possessed by water is further explored. On the basis of Martin's functional derivative formulation of Ising problems, a perturbation scheme is developed which allows calculation of the free energy to any desired order in the interaction potential at fixed density. The free energy correct to second order in the interaction strength is utilized here for calculation of other thermodynamic properties of the model. With reasonable choices of values of the interaction parameters these thermodynamic properties of the model can be brought into agreement with those of real water.     

Saturation of the free exciton resonance in GaAs

The transmission of 500 ns pulses through GaAs-AlGaAs heterostructures has been studied as a function of light intensity (0.015 to 50 kW/cm²) and wavelength (810 to 840 nm). The intrinsic exciton absorption (λ=818 nm at 10°K) can be modeled by the sum of a small unsaturable background and a dominant term which saturates as a Bloch resonance with a saturatiom parameter of about 150 W/cm².