14 research outputs found
Electron-impact ionization and ionic fragmentation of O from threshold to 120 eV energy range
We study the electron-impact induced ionization of O from threshold to
120 eV using the electron spectroscopy method. Our approach is simple in
concept and embodies the ion source with a collision chamber and a mass
spectrometer with a quadruple filter as a selector for the product ions. The
combination of these two devices makes it possible to unequivocally collect all
energetic fragment ions formed in ionization and dissociative processes and to
detect them with known efficiency. The ion source allows to vary and tune the
electron-impact ionization energy and the target-gas pressure. We demonstrate
that for obtaining reliable results of cross sections for inelastic processes
and determining mechanisms for the formation of O()
ions, it is crucial to control the electron-impact energy for production of ion
and the pressure in the ion source. A comparison of our results with other
experimental and theoretical data shows good agreement and proves the validity
of our approach.Comment: 11 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:1905.0114
Excitations of N and O molecules due to helium ion impact and a polarization effect
We present an experimental study of the dissociative excitation in the
collision of helium ions with nitrogen and oxygen molecules for collision
energy of keV. Absolute emission cross sections are measured and
reported for most nitrogen and oxygen atomic and ionic lines in wide, vacuum
ultraviolet ( nm) and visible ( nm), spectral regions.
Remarkable similarities of the processes realized in HeN and
HeO collision systems are observed. We present polarization
measurements for HeN 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 cm or lower.Comment: 14 pages, 7 figure
Emission cross sections for energetic O()-N collisions
We report measurements of excitation functions for the ON
process with the incident beam of keV O in the ground
O and metastable O and O states. The
measurements are performed with the sufficiently high energy resolution of
0.001 eV, which allows to distinguish the excitation channels. The excitation
cross section induced by incident ions in the metastable state O
is much larger than that for the ground O. The excitation cross
section of N ion for (0,0), (0,1) and (1,2) bands system is measured
and the ratio of intensities for these bands is established as It is
shown that the cross sections for the Nions excitations in the
dissociative charge exchange processes increase with the increase of the
incident ion energy. The energy dependence of the excitation cross section of
the band (0,0) nm of the first negative system of the
N and degree of polarization of radiation in ON
collision are measured for the first time. An influence of an admixture of the
ion metastable state on a degree of polarization is revealed. It is
demonstrated that for ON collision system the degree of
polarization by metastable O() ions is less compared to those that
are in the ground O() state and the sign of polarization degree of
excited molecular ions does not change.Comment: 15 pages, 8 Figure
DISSOCIATIVE EXCITATION, IONIZATION, AND FRAGMENTATION PROCESSES FOR NITROGEN, OXYGEN, METHANE, AND WATER MOLECULES BY ELECTRON BOMBARDMENT
Electron–impact ionization and fragmentation of molecules are investigated by the chromatography mass-spectrometry device. While the excitation processes are investigated by an optical spectroscopy method. The spectral analysis is performed in the vacuum ultraviolet 50-130 nm spectral regions. The absolute value of the fragmentation cross-section in the dissociative ionization and excitation processes is determined. Measurements are performed in the electron energy range 25-120eV for ionization and 200-500eV for excitation processes respectively
Electron-Impact Ionization and Ionic Fragmentation of Oâ‚‚ from Threshold to 120 eV Energy Range
We study the electron-impact induced ionization of O2 from threshold to 120 eV using the electron spectroscopy method. Our approach is simple in concept and embodies the ion source with a collision chamber and a mass spectrometer with a quadruple filter as a selector for the product ions. The combination of these two devices makes it possible to unequivocally collect all energetic fragment ions formed in ionization and dissociative processes and to detect them with known efficiency. The ion source allows varying and tuning the electron-impact ionization energy and the target-gas pressure. We demonstrate that for obtaining reliable results of cross-sections for inelastic processes and determining mechanisms for the formation of O+(4S, 2D, 2P) ions, it is crucial to control the electron-impact energy for production of ion and the pressure in the ion source. A comparison of our results with other experimental and theoretical data shows good agreement and proves the validity of our approach