Mise en évidence de l'oxygène singulet 1Δg a 200 mbar dans une décharge contrôlée par faisceau d'électrons

The radiation from molecular oxygen metastables is observed at visible and infrared wavelengths. The results are quite different from those obtained with a corona discharge.Le rayonnement des métastables de l'oxygène moléculaire est observé dans le visible et l'infrarouge. Les résultats diffèrent nettement de ceux obtenus avec une décharge couronne

Kinetics of species produced by an electron-beam controlled discharge in oxygen at atmospheric pressure

Time evolution of charged species, metastable species and ozone is obtained from a computer code. Some results can be compared with previous experiments.L'évolution dans le temps des espèces chargées, des métastables et de l'ozone est obtenue à l'aide d'un programme de calcul. Certains résultats sont comparés à des expériences antérieures

Fluorescence yield and lifetime of isolated polydiacetylene chains: Evidence for a one-dimensional exciton band in a conjugated polymer

The fluorescence lifetime tau and quantum yield eta(f) of isolated red polydiacetylene chains dispersed in their monomer single crystal matrix were measured between 10 and 100 K. tau increases up to 120 ps at 40 K, then rapidly decreases at higher T. eta(f) is a continuously decreasing function of T. The radiative lifetime tau(r) is proportional to rootT in the whole T range studied. This is the expected behavior for a purely one-dimensional system without localization, a behavior which is not usually observed even in semiconductor quantum wires. An order of magnitude of the exciton effective mass m*approximate to0.3 is inferred. The nonradiative lifetime tau(nr) is constant up to 50 K, then decreases exponentially, indicating the opening of a thermally activated decay channel