Autoionization cross section of potassium atom excited by electron impact

Borovik, A

doi:10.1134/s1063784212080051

Cited by 4 publications

(4 citation statements)

References 19 publications

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“…Close to the excitation thresholds of the 1s 2 and np 6 shells, the shape of all cross sections possesses the evident resonance character. This behaviour reflects the common for sub-valence [11], Na (present data), K [12,48], Rb [13], and Cs [14,49] atoms excited by electron impact. shells in alkalies efficient formation of negative-ion resonances by electron impact (see e.g.…”

Section: Alkali Group Li-cssupporting

confidence: 85%

“…However, if in Li and Na atoms, the observed structure is caused by the negative-ion resonances formed predominately on the basis of the lowest doublet autoionizing levels (see [11] and section 3.1 above), in K, Rb and Cs atoms, the resonance excitation of quartet levels becomes dominant. Indeed, as was shown earlier [12,14,48], just quartet autoionizing levels are responsible for the presence of the strong maximum of the EA cross section at approximately 2-7 eV above the p 6 threshold, whereas only a small near-threshold feature reflects the resonance excitation of the (np 5 [n+1]s 2 ) 2 P lowest doublet levels (see figure 4). Considering the relative role of doublet and quartet autoionizing levels in formation of the EA cross section of alkali atoms, one may conclude that it is formed mainly by the doublet levels in Li and Na atoms and by the quartet levels in K and Rb atoms.…”

Section: Alkali Group Li-cssupporting

confidence: 61%

“…Figure 4. The EA cross sections of Li[11], Na (present data), K[12,48], Rb[13], and Cs[14,49] atoms excited by electron impact.…”

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confidence: 70%

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Excitation-autoionization cross section of alkali atoms by electron impact

Borovik¹,

Kupliauskiene²,

Zatsarinny³

2013

J. Phys. B: At. Mol. Opt. Phys.

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The excitation-autoionization (EA) cross section of Na atoms was obtained experimentally in the form of normalized intensities of autoionizing spectra measured in the ejected-electron energy region between 25.5 and 33.7 eV for electron impact energies from the 2p6 excitation threshold at 30.77 up to 400 eV. The cross section exhibits the strong resonance behaviour in the near-threshold region and reaches the maximum value of 1.2 × 10−17 cm2 at 200 eV. By assigning the lines in ejected-electron spectra, the relative role of the 2p6 and 2s2 subshells as well as quartet and doublet levels in formation of the EA cross section was estimated. In particular, the autoionizing doublets in 2p53sns(n = 3 − 6), np(n = 3 − 6), nd(n = 3 − 4) configurations provide approximately 80% of the EA cross section at 200 eV impact energy. A comparative analysis of the EA cross sections for whole alkali group Li–Cs indicates that the near-threshold resonance behaviour of all cross sections is caused exclusively by the negative-ion resonances formed on the basis of the levels 1sn1l1n2l2 in Li and np5n1l1n2l2 in Na–Cs atoms. The relative EA contribution to the total single ionization cross section does not exceed 2% in Li and 5% in Na, and reaches 26% in K, 32% in Rb and 39% in Cs atoms.

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Section: Alkali Group Li-cssupporting

confidence: 85%

Section: Alkali Group Li-cssupporting

confidence: 61%

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Excitation-autoionization cross section of alkali atoms by electron impact

Borovik¹,

Kupliauskiene²,

Zatsarinny³

2013

J. Phys. B: At. Mol. Opt. Phys.

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“…Feng and Zhang [17] measured the photoionization cross-section from the 7p excited state whereas, Amin et al [18] reported the photoionization cross-sections from the 4p, 5d and 7s excited states using the saturation technique in conjunction with a thermionic diode ion detector. Borovick [19] measured the autoionization cross-section of potassium atoms excited by electron impact in the energy range from 18.72 to 202 eV. Recently, Yar et al [20,21] reported the photoionization cross-section from the 6p and 7s-states of potassium.…”

Section: Introductionmentioning

confidence: 99%

Two-step laser excitation and ionization from the 7p²P_3/2state of potassium

Yar¹,

Iqbal²,

Ali³

et al. 2015

Laser Phys.

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New measurements of photoionization cross-sections from the 7p 2 P 3/2 excited state of potassium near the first ionization threshold are presented using a two-step laser excitation/ ionization technique in conjunction with a time-of-flight (TOF) mass spectrometer. The absolute values of photoionization cross-sections have been determined as (3.52 ± 0.52) Mb, (2.21 ± 0.33) Mb, (1.35 ± 0.22) Mb and (0.54 ± 0.08) Mb at four ionizing laser wavelengths; 1064 nm, 643.61 nm, 532 nm and 355 nm respectively whereas the number density has been determined as (1.6 ± 0.31) × 10 10 cm −3 . The presently measured experimental values of photoionization cross-sections are in good agreement with the literature experimental and theoretical values.

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Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko

Würz

Rubin

Altwegg

et al. 2015

A&A

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Aims. Far away from the Sun, at around 3 AU, the activity of comet 67P/Churyumov-Gerasimenko is low and changes with local time (solar insolation), with location (chemical heterogeneity of the surface), and with season. When the activity is very low because the total cross section of the comet against the Sun is small, the solar wind has access to the surface of the comet and causes ion-induced sputtering of surface material, which we wish to observe. Methods. We used the Double Focussing Mass Spectrometer (DFMS) of the ROSINA experiment on ESA's Rosetta mission to search for mass spectrometric evidence of sputtered refractory species. In high-resolution mode, DFMS can separate some of the mass peaks of refractory elements from the many volatile species present in the coma. Results. At present, the locations of solar wind surface access are in the southern hemisphere of the comet (the local winter). Of particular interest is sputtering of dust grains on the surface. We observe global averages over the winter hemisphere of the refractory elements Na, K, Si, and Ca, presumably sputtered from grains residing on the surface. Compared to carbonaceous chondrites, the comet has the same Na abundance, is depleted in Ca, and has an excess of K. In addition, for Si the signal strength is strong enough to compile a coarse compositional map of the southern hemisphere. Most, perhaps all, of the observed variation can be explained by the solar wind being affected by the atmosphere of the comet.

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Autoionization cross section of potassium atom excited by electron impact

Cited by 4 publications

References 19 publications

Excitation-autoionization cross section of alkali atoms by electron impact

Excitation-autoionization cross section of alkali atoms by electron impact

Two-step laser excitation and ionization from the 7p²P_3/2state of potassium

Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko

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Autoionization cross section of potassium atom excited by electron impact

Cited by 4 publications

References 19 publications

Excitation-autoionization cross section of alkali atoms by electron impact

Excitation-autoionization cross section of alkali atoms by electron impact

Two-step laser excitation and ionization from the 7p2P3/2state of potassium

Solar wind sputtering of dust on the surface of 67P/Churyumov-Gerasimenko

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Two-step laser excitation and ionization from the 7p²P_3/2state of potassium