We report measurements of the absolute differential cross sections for charge-transfer scattering of 0.5, 0.85, 1.5, 2.8 and 5 keV O + ions by CO 2 at scattering angles between 0.04 • and 2.9 • in the laboratory frame. Cross sections for both O + ( 4 S) ground-state and O + ( 2 D, 2 P) metastable ions are presented. The angular dependence of the differential cross sections is similar for both ground-state and metastable ions but the ground-state integral cross section is greater than that for metastable ions over most of the energy range considered. † Present address:

The electron diffusion length is directly evaluated from the dependence of photocurrent on the position of dyeadsorption front using the structure of selectively dye-adsorbed solar cell. By changing the thickness of the region without dye-adsorption, the thickness that the photocurrent starts to flow is defined as the electron diffusion length in nano-porous TiO2 layer. This method is applied to investigate the effects of the electrolyte solvent and the annealing temperature on the electron diffusion length in nano-porous TiO2 layer. It is suggested that viscosity and molecular size of solvent affects the diffusion of electron in TiO2 nano-porous layer from the results that the electron diffusion length is 1.6 times longer in aprotic acetonitrile solvent than in protic ethylene glycol solvent. At 600 • C annealing, the electron diffusion length shows the maximum of 27 ± 1 µm in LiI/I2/acetonitlire at the incident photon flux of 2.2 × 10 15 cm −2 s −1 at 540 nm.