We compare the electronic structure of differently fluorinated copper phthalocyanines (CuPC, ${\mathrm{CuPCF}}_4,$ and ${\mathrm{CuPCF}}_{16})$ using x-ray photoemission spectroscopy and valence-band ultraviolet photoemission spectroscopy. Whereas the ionization potential (IP) is increased by more than 1 eV as a function of the degree of fluorination, further electronic properties such as the optical gap or the composition of the highest occupied molecular orbital and lowest unoccupied molecular orbital remain nearly unchanged. This fact renders these compounds an ideal tool for the investigation of the influence of the IP on the interface properties. At the interface to gold, besides interface dipoles we observe both downward and upward band bending. These phenomena depend clearly on the IP of the phthalocyanines.

We report a detailed experimental and theoretical study on the electronic and optical properties of highly boron-substituted (up to $15\text{at.}\%$) single-wall carbon nanotubes. Core-level electron energy-loss spectroscopy reveals that the boron incorporates into the lattice structure of the tubes, transferring $\sim 1∕2$ hole per boron atom into the carbon derived unoccupied density of states. The charge transfer and the calculated Fermi-energy shift in the doped nanotubes evidence that a simple rigid-band model can be ruled out and that additional effects such as charge localization and doping induced band-structure changes play an important role at this high doping levels. In optical absorption a new peak appears at $0.4\text{eV}$ which is independent of the doping level. Compared to the results from a series of ab initio calculations our results support the selective doping of semiconducting nanotubes and the formation of ${\text{BC}}_3$ nanotubes instead of a homogeneous random boron substitution.

We report on electron energy-loss spectroscopy studies of the electronic properties of multiwall boron nitride nanotubes, in terms of the $\mathrm{B}1s$ and $\mathrm{N}1s$ excitation edges and of the q-dependent energy-loss function. The q-dependent dielectric function shows a strong dispersion in momentum of the π and $\sigma +\pi$ plasmons indicating that they are spatially delocalized along the tube axis as expected according to their characteristic two-dimensional graphiticlike structure, and nondispersing excitations at 11 and 12 eV. The dielectric function ɛ of the boron nitride nanotubes reveals an intense $\pi -{\pi }^{*}$ interband transition at 5.4 eV, which is shifted to lower energies by 0.6 eV when compared to hexagonal BN in good agreement with recent theoretical band-structure calculations of boron nitride nanotubes.