Samantha Fonseca dos Santos

Dissociative recombination of H3+ in the ground and excited vibrational states

The article presents calculated dissociative recombination (DR) rate coefficients for H3+. The previous theoretical work on H3+ was performed using the adiabatic hyperspherical approximation to calculate the target ion vibrational states and it considered just a limited number of ionic rotational states. In this study, we use accurate vibrational wave functions and a larger number of possible rotational states of the H3+ ground vibrational level. The DR rate coefficient obtained is found to agree better with the experimental data from storage ring experiments than the previous theoretical calculation. We present evidence that excited rotational states could be playing an important role in those experiments for collision energies above 10meV. The DR rate coefficients calculated separately for ortho- and para-H3+ are predicted to differ significantly at low energy, a result consistent with a recent experiment. We also present DR rate coefficients for vibrationally excited initial states of H3+, which are fo...

Propagation of high-frequency surface plasmons on gold

Propagation of surface plasmons on gold in the range 2.8-3.5 eV over 0.1-1.6 μm distances was characterized by cathodoluminescence spectroscopy. Surface plasmons were excited by an electron beam near a grating milled in the gold. The spectra of outcoupled radiation reveal increasingly strong propagation losses as surface plasmon energy increases above 2.8 eV, but little effect in the range 1.6-2.8 eV. These results are in partial agreement with theoretical expectations.