Simultaneous Ionization and Excitation of Molecules by Positron Impact

Positron-impact ionization, positronium formation, and electronic excitation cross sections for diatomic molecules

Absolute measurements are presented for the positron-impact cross sections for positronium formation, direct ionization, and total ionization of the diatomic molecules N2, CO, and O2, in the range of energies from threshold to 90 eV. Cross sections for the electronic excitation of the a 1 and a 1 state in N2 and the A 1 state in CO near threshold are also presented. The experiment uses a cold, ...

Excitation of molecular vibrations by positron impact.

Absolute cross sections for the vibrational excitation of CO, CO2, and H2 by positron impact are presented for incident positron energies from 0.5 eV to several electron volts. The measurements use a novel technique that exploits the adiabatic motion of a positron beam in a strong magnetic field. This work is the first systematic experimental study of vibrational excitation by positron impact, ...

Simultaneous ionization-excitation of helium to He„2p... magnetic sublevels by proton impact

Experimental magnetic substate cross section ratios s0 /s1 and scattering angle-integrated cross sections following ionization-excitation of helium to He(2p) P in H1He collisions have been determined, using polarization measurements of emitted radiation in the extreme ultraviolet region in combination with total cross sections, over a wide range of proton velocities ~2–6 a.u.!. These results ar...

K-shell ionization of atoms by electron and positron impact.

Electron-Impact Excitation and Ionization in Air

In a partially ionized hypersonic flow field, electron collision plays a significant role in energy re-distribution and in the production of excited states of atoms and molecules that can subsequently radiate. Thus electron collision data is part of the database used in modelling high speed entry flows. First principles computational methods for the calculation of electron-impact data are revie...