Differential excitation cross sections have been measured for Kr 4p ('So)~4p'( Pl/2 3/2)5s transitions at 300and 500-eV impact energies and for 1. 5'-10' scattering angles by electron-energy-loss spectroscopy. The integrated cross sections for these impact energies are reported here. The generalized oscillator strengths have also been obtained to determine the optical oscillator strengths.The errors are estimated to be less than 15%.
The intermediate frequency Raman mode (IFM) in the range from 300 to 500 cm −1 of individually suspended single-walled carbon nanotubes (SWCNTs) was assessed to determine the effects of chirality and defect density. Photoluminescence spectroscopy was employed to confirm isolation and chirality of the SWCNTs. The IFM frequency exhibited a positive correlation with the nanotube diameter, as expected from prior studies. Raman and photoluminescence measurements were conducted simultaneously with the introduction of defects into a SWCNT. The photoluminescence intensity showed the largest reduction rate among all optical peaks analyzed. Furthermore, the intensity of the IFM increased with defect creation and showed almost the same behavior as the D-mode intensity. These results can be explained by the increase of the exciton−phonon coupling in the defective SWCNTs. Unambiguous chirality assignment using photoluminescence spectroscopy, along with employment of individually suspended samples that minimize environmental effects, enabled us to investigate the intrinsic nature of the IFM.
Interfacial water can exist between graphene and a substrate surface in ambient air. The effects of water on the electrical properties of graphene are complex and depend on the substrate material. We investigated the effects of interfacial water formed between graphene and a SiO2/Si substrate according to the Raman spectra. The effect of the interfacial water was influenced by the hydrophilicity of the SiO2 surface. While the interfacial water inhibited the charge transfer between graphene and SiO2, it induced hole-doping in graphene because of the dipole moment of the water molecules aligned on the highly hydrophilic SiO2 surface.
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