Fluorescent polymeric aggregates for selective response to sarin surrogates.

By combining the sensitivity of fluorescent units with the response of "smart" polymers to environmental changes, we propose a new approach for chemical detection applications. The system proved to be sensitive to 12 ppb of diethyl chlorophosphate (DCP), a Sarin surrogate, and to discriminate between the interfering molecules.

Direct observation of athermal photofluidisation in azo-polymer films.

The surface relief gratings (SRGs) can be generated when azo-polymer films are exposed to laser beam interference as a result of mass migration. Despite considerable research effort over the past two decades this complex phenomenon remains incompletely understood. Here we show, for the first time, the athermal photofluidisation of azo-polysiloxane films exposed to 488 nm light, directly monitored by optical microscopy.

Distributed feedback lasing of commercial liquid scintillators.

It is shown that lasing can be achieved in commercial organic liquid scintillators. Using a dynamic grating induced by an interference pattern in the scintillator volume, distributed feedback lasing is shown to occur in four out of five commercial liquid scintillators that have been investigated. Although these scintillators are not designed for lasing application, their purpose being to measure radioactivity, induction of a laser effect, furthermore with a tuning range of approximately 30 nm, has been attained.

ZnO nanowires as effective luminescent sensing materials for nitroaromatic derivatives.

We report on the efficient room-temperature photoluminescence (PL) quenching of ZnO in the presence of 2,4-dinitrotoluene (DNT) vapor and for concentration as low as 180 ppb. Compared to ZnO thin films, ZnO nanowires exhibit a strong (95%) and fast (41 s) quenching of the PL intensity in the presence of DNT vapor. Assuming that the PL quenching is due to a trapping of the ZnO excitons by adsorbed DNT molecules, Monte-Carlo calculations show that the nanometric dimensions as well as the better crystallographic quality (longer mean free path) of the ZnO nanowires result in an enhanced trapping process at the origin of the improved sensing properties of the nanowires.

Azo-polysiloxanes as new supports for cell cultures.

The paper introduces a new class of materials with azo-polysiloxanic structure bearing the property to generate nano-structured surfaces by laser irradiation. The ability to modulate the optical response of the film, through a modification of the polymer chemical structure, has been investigated. The azo-materials were tested for their ability to support cell adhesion and growth, with very promising results.