Evidence of polariton induced transparency in a single organic quantum wire

The resonant interaction between quasi-one dimensional excitons and photons is investigated. For a single isolated organic quantum wire, embedded in its single crystal monomer matrix, the strong exciton-photon coupling regime is reached. This is evidenced by the suppression of the resonant excitonic absorption arising when the system eigenstate is a polariton. These observations demonstrate that the resonant excitonic absorption in a semiconductor can be understood in terms of a balance between the exciton coherence time and the Rabi period between exciton-like and photon-like states of the polariton.Comment: 9 pages and 4 figure

Model of surface instabilities induced by stress

We propose a model based on a Ginzburg-Landau approach to study a strain relief mechanism at a free interface of a non-hydrostatically stressed solid, commonly observed in thin-film growth. The evolving instability, known as the Grinfeld instability, is studied numerically in two and three dimensions. Inherent in the description is the proper treatment of nonlinearities. We find these nonlinearities can lead to competitive coarsening of interfacial structures, corresponding to different wavenumbers, as strain is relieved. We suggest ways to experimentally measure this coarsening.Comment: 4 pages (3 figures included

Formation of periodic crack structures in polydiacetylene single crystal thin films

The formation of a regular pattern of periodic cracked ridges on single crystal polydiacetylene films is described. Films thicker than a certain critical thickness are cracked while thinner ones are not. A model in the framework of linear elasticity theory is developed, which accounts for this transition as a function of the film thickness.Nous décrivons ici les conditions d'apparition d'un réseau de fractures périodiques dans des films monocristallins de polydiacétylène. Les films dont l'épaisseur est supérieure à une certaine épaisseur critique présentent ces fractures, tandis que les plus minces ne sont pas fracturés. Un modèle basé sur la théorie élastique linéaire rend compte de cette épaisseur critique