1,721,133 research outputs found
On the influence of multiple reflections on the electroreflectance spectrum of the ground-exciton line of GaSe
No full textReversibile inhibition of the pollen germination and the stigma penetration in Crocus vernus ssp.vernus (Iridaceae) following fumigation with NO2, CO, and O3 gases
No full textWe assessed the pollen hydration, the pollen germination, and the stigma papilla penetration of CROCUS VERNUS subsp. VERNUS (Iridaceae) after 2 h fumigations with O (3), NO (2), and CO gases within humidified (90 - 100 % RH) box experiments. When the pollen and the pistil were separately fumigated, the pollen retained the capacity to emit a tube which penetrated papilla, and the stigma papillae retained the receptivity; when the pistils were first pollinated and then fumigated, the capacity of pollen to hydrate was not affected, but the germination was significantly reduced. The vulnerability to gases became evident at 0.3 ppm O (3), 0.2 ppm NO (2), and 0.5 ppm CO. The inhibition curves as a function of the gas concentrations were of an exponential type, and they saturated at 2 ppm NO (2), 25 ppm CO, and 0.5 ppm O (3), with germination percentages of 17 %, 27 %, and 60 %, respectively. Both the pollen germination and the papilla penetration were fully restored by prolonging for 60 - 90 min the incubation at 90 - 100 % RH, after the cessation of fumigations. The vulnerability of the pollen-papilla system is discussed
Polarization effects in the electroreflectance of bismuth telluride at oblique incidence
No full textThe optical transitions above the threshold of the uniaxial crystal bismuth telluride have been investigated by means of electroreflectance over the energy range 1-5.5 eV using an electrolyte to produce electric fields at the surface. Both near-normal and oblique incidence measurements were made using light polarized under different orientations of the electric vector with respect to the c axis. The combination of these techniques permitted an unambiguous identification of the symmetry of the critical points and yielded the precise polarization dependence of the transitions. The broad electroreflectance spectra of bismuth telluride have been understood and analyzed in terms of strongly lifetime-broadened Franz-Keldysh tunneling. A correlation, although preliminary, has been attempted with the band structure of this material
Determination of the optical constants of the Si-SiO2 system by the method of the angular modulation of reflectance
No full textNew method for determining the optical constants by the angular modulation of reflectance
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INVESTIGATION ON ELECTRONIC-STRUCTURE OF CU CLUSTERS ON GRAPHITE BY EELS AND XPS STUDIES
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