Excitations of N${}_2$ and O${}_2$ molecules due to helium ion impact and a polarization effect

Abstract

We present an experimental study of the dissociative excitation in the collision of helium ions with nitrogen and oxygen molecules for collision energy of $0.7-10$ keV. Absolute emission cross sections are measured and reported for most nitrogen and oxygen atomic and ionic lines in wide, vacuum ultraviolet ($80-130$ nm) and visible ($380-800$ nm), spectral regions. Remarkable similarities of the processes realized in He${}^{+}+$N${}_2$ and He${}^{+}+$O${}_2$ collision systems are observed. We present polarization measurements for He${}^{+}+$N${}_2$ collision system. The emission of excited dissociative products was detected using an improved high-resolution optical spectroscopy method. This method incorporates the retarding potential method and a high resolution electrostatic energy analyzer to precisely measure the energy of incident particles and the energy of dispersion. The improvement in the optics resolution allows us to measure the cross section on the order of 10${}^{-19}$ cm${}^2$ or lower.

14 pages, 7 figures