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971.
Gain coefficients have been calculated for transitions of singlet levels ns–np of orbital n=4 and n=5 in magnesium-like ions with atomic numbers Z=18, 19, 20, 21, 22 and 23. Population inversions for 4p and 5p levels in these ions were also calculated, via electron collisional excitation, for electron temperature range of 93–231 eV and electron density range of 1016–1017 cm−3. Under these plasma conditions, the maximum gain that occurred for 4s–4p transition was at electron temperature of 231 eV and electron density of 4×1017 cm−3. Scaling of the maximum gain coefficients with atomic number Z and the plasma parameters is also presented. 相似文献
972.
973.
Lindenberg AM Engemann S Gaffney KJ Sokolowski-Tinten K Larsson J Hillyard PB Reis DA Fritz DM Arthur J Akre RA George MJ Deb A Bucksbaum PH Hajdu J Meyer DA Nicoul M Blome C Tschentscher T Cavalieri AL Falcone RW Lee SH Pahl R Rudati J Fuoss PH Nelson AJ Krejcik P Siddons DP Lorazo P Hastings JB 《Physical review letters》2008,100(13):135502
Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process. 相似文献
974.
Ultraviolet and infrared conical emissions were observed during the filamentation in air of powerful femtosecond laser pulses produced by a portable terawatt laser system. The broadband spectrum was measured from 200 nm up to 14 microm and covered the complete optical transmission window of the atmosphere. The angularly resolved spectrum showed some X-wave structure across the frequency range analyzed. However, we demonstrated that the strong conical emission observed in the mid- and far-infrared is mainly owing to the four-wave mixing between the pump pulse and its blueshifted conical emission. 相似文献
975.
We investigate trapped cold Bose gases using the stochastic variational approach with realistic attractive finite-range two-body interactions. We study the properties of the Bose-Einstein condensates, particularly in the large scattering-length regime, and establish the existence of meta-stable many-body Efimov states. 相似文献
976.
A photoacoustic (PA) sensor has been developed to monitor hydrogen chloride at sub-ppm level in the 1740-nm region. The system
was designed to control the process in the novel low-water-peak optical fiber manufacturing process. Relaxation effects in
hydrogen chloride PA detection in oxygen–helium and nitrogen–helium gas mixtures are presented, showing that the generation
of the PA signal is strongly affected by the ratio of these substances. In addition, the role of water vapor in the PA signal
is investigated. 相似文献
977.
The system TiO2–photo sensitive dye of a dye-sensitized TiO2 solar cell is numerically simulated. The steady-state numerical model used is based on the continuity and transport equations
for all charge species involved in the system, in connection to Poisson’s equation. The dependence of both electron diffusion
coefficient and light absorbance upon TiO2 porosity is taken into consideration. The resulting electron density after illumination is also set as a function of the
illuminating beam characteristics and material properties. Furthermore, an effective dielectric constant dependent upon the
porosity of TiO2 is used in the model. Results for different values of pore size and thickness of the TiO2 electrode are found in accordance with results reported in the literature.
Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007.
An erratum to this article can be found at 相似文献
978.
979.
980.