The dependence of the free charge carrier concentration on light intensity is analyzed in two types of crystals where photorefractive centers are either traps or donors. Conditions under which the dependence becomes sublinear at relatively low light intensities are established. 相似文献
The addition of calix[4]arenes to MeCN/H2O or MeOH/MeCN/THF/H2O mobile phases improves LC separation of benzene or uracil derivatives on Separon SGX C18 or Separon SGX NH2 supports. Structure of the calixarenes and their host–guest supramolecular complexes with the analytes are discussed in context of the LC separation. 相似文献
In this letter, we report on the use of tin as an effective surfactant material for silver growing on silicon oxide. We observed that submonolayers of Sn pre-deposited on SiO2 result in earlier film coalescence and formation of smoother Ag layers. We suggest that Sn atoms reduce the Ag-adatom mobility resulting in experimentally observed increased island density and decreased film roughness. Angle-resolved X-ray photoelectron spectroscopy reveals that Sn remains under the Ag layer giving circumstantial evidence that at later stages of Ag film growth Sn does not influence the interlayer transport. 相似文献
The aim of the current work was to determine thermo dynamical properties of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde.
Results
The temperature dependence of saturated vapor pressure of 5(2-nitro phenyl)-furan-2-carbaldehyde, 5(3-nitro phenyl)-furan-2-carbaldehyde and 5(4-nitro phenyl)-furan-2-carbaldehyde was determined by Knudsen’s effusion method. The results are presented by the Clapeyron–Clausius equation in linear form, and via this form, the standard enthalpies, entropies and Gibbs energies of sublimation and evaporation of compounds were calculated at 298.15 K. The standard molar formation enthalpies of compounds in crystalline state at 298.15 K were determined indirectly by the corresponding standard molar combustion enthalpy, obtained using bomb calorimetry combustion.
Conclusions
Determination of the thermodynamic properties for these compounds may contribute to solving practical problems pertaining optimization processes of their synthesis, purification and application and it will also provide a more thorough insight regarding the theoretical knowledge of their nature.
It has been previously observed that the measured frequency of ions in a Fourier transform mass spectrometry experiment depend
upon the number of trapped ions, even for populations consisting exclusively of a single mass-to-charge. Since ions of the
same mass-to-charge are thought not to exert a space-charge effect among themselves, the experimental observation of such
frequency shifts raises questions about their origin. To determine the source of such experimentally observed frequency shifts,
multiparticle ion trajectory simulations have been conducted on monoisotopic populations of Cs+ ranging from 102 ions to 106 ions. A close match to experimental behavior is observed. By probing the effect of ion number and orbital radius on the shift
in the cyclotron frequency, it is shown that for a monoisotopic population of ions, the frequency shift is caused by the interaction
of ions with their image-charge. The addition of ions of a second mass-to-charge to the simulation allows the comparison of
the magnitude of the frequency shift resulting from space-charge (ion-ion) effects versus ion interactions with their image
charge. 相似文献