H Kawahara

Cross sections for electron impact excitation of the C Π1 and D Σ1+ electronic states in N2O

Differential and integral cross sections for electron-impact excitation of the dipole-allowed C (1)Pi and D (1)Sigma(+) electronic states of nitrous oxide have been measured. The differential cross sections were determined by analysis of normalized energy-loss spectra obtained using a crossed-beam apparatus at six electron energies in the range 15-200 eV. Integral cross sections were subsequently derived from these data. The present work was undertaken in order to check both the validity of the only other comprehensive experimental study into these excitation processes [Marinkovic et al., J. Phys. B 32, 1949 (1998)] and to extend the energy range of those data. Agreement with the earlier data, particularly at the lower common energies, was typically found to be fair. In addition, the BEf-scaling approach [Kim, J. Chem. Phys. 126, 064305 (2007)] is used to calculate integral cross sections for the C (1)Pi and D (1)Sigma(+) states, from their respective thresholds to 5000 eV. In general, good agreement is found between the experimental integral cross sections and those calculated within the BEf-scaling paradigm, the only exception being at the lowest energies of this study. Finally, optical oscillator strengths, also determined as a part of the present investigations, were found to be in fair accordance with previous corresponding determinations.

Integral cross sections for electron impact excitation of the 1Σ+u and 1Πu electronic states in CO2

We apply the method of Kim (2007 J. Chem. Phys. 126 064305) in order to derive integral cross sections for the 1 � + u and 1 � u states of CO2, from our corresponding earlier differential cross section measurements (Green et al 2002 J. Phys. B: At. Mol. Opt. Phys. 35 567). The energy range of this work is 20‐200 eV. In addition, the BEf -scaling approach is used to calculate integral cross sections for these same states, from their respective thresholds to 5000 eV. In general, good agreement is found between the experimental integral cross sections and those calculated within the BEf -scaling paradigm, over the entire common energy range. Finally, we employ our calculated integral cross sections to determine the electron energy transfer rates for these states, for a thermal electron energy distribution. Such transfer rates are in principle important for understanding the phenomena in atmospheres where CO2 is a dominant constituent, such as on Mars and Venus. (Some figures in this article are in colour only in the electronic version)

Integral cross sections for electron impact excitation of the 1[Sigma]+u and 1[Pi]u electronic states in CO2

We apply the method of Kim (2007 J. Chem. Phys. 126 064305) in order to derive integral cross sections for the 1 � + u and 1 � u states of CO2, from our corresponding earlier differential cross section measurements (Green et al 2002 J. Phys. B: At. Mol. Opt. Phys. 35 567). The energy range of this work is 20‐200 eV. In addition, the BEf -scaling approach is used to calculate integral cross sections for these same states, from their respective thresholds to 5000 eV. In general, good agreement is found between the experimental integral cross sections and those calculated within the BEf -scaling paradigm, over the entire common energy range. Finally, we employ our calculated integral cross sections to determine the electron energy transfer rates for these states, for a thermal electron energy distribution. Such transfer rates are in principle important for understanding the phenomena in atmospheres where CO2 is a dominant constituent, such as on Mars and Venus. (Some figures in this article are in colour only in the electronic version)

Application of the BEf-scaling approach to electron impact excitation of diople-allowed electronic states in molecules

We consider the efficacy of the BEf-scaling approach, in calculating reliable integral cross sections for electron impact excitation of dipole-allowed electronic states in molecules. We will demonstrate, using specific examples in H2, CO and H2O, that this relatively simple procedure can generate quite accurate integral cross sections which compare well with available experimental data. Finally, we will briefly consider the ramifications of this to atmospheric and other types of modelling studies.

Development of a new set-up for Cold Electron Collision experiment utilizing the threshold photoelectrons

A new type of the experimental set-up for the measurements of the total cross section for collisions between electrons and atoms or molecules at very low collision energies, which are called as Cold Electron Collisions. The key of this set-up is to use the threshold photoelectrons as a source for low-energy electron beam combined with the penetration field method. Total cross sections measurements over the energy range from thermal energy to 12eV with high-energy resolution by this new set-up are presented.