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1.
The present work deals with the spectroscopic investigation of Penning ionization and nonresonant charge exchange due to thermal-energy collisions of metastable atoms or ions of the inert gases He, Ne with atoms of alkali metals K, Rb, Cs in a low temperature plasma of the corresponding binary mixtures. The rate constants of these reactions and partial rate constants of exciting several alkali metal ion levels were determined by the kinetics of the decay of ionized and excited particles in the afterglow of a pulsed discharge. Measured Penning and charge exchange constants are in order of 1010-9 cm3 sec?1. Partial Penning constants in the He? Cs system exhibit a small dependence of the energy defect of reaction, whereby an important part of collisions results in excited Cs+-states. On the contrary, energy transfer by charge exchange in He? Rb, Cs systems distinguishes by a significant energy defect dependence. Charge exchange from He+ to Rb0 leads above all to He(23S1)-atoms and normal Rb+-ions. It follows from the metal ion spectrums, that Penning ionization and charge exchange of the investigated systems under utilized conditions represent as processes of selective excitation of alkali metal ions in afterglow and stationary discharge. 相似文献
2.
The electron spectra resulting from thermal collisions of He* (predominantly 23S) metastable atoms with the seven triatomic molecules, CO2, COS, CS2, N2O H2S, SO2 and NO2, are compared with their respective 584-Å photoelectron spectra using a transmission-corrected electron spectrometer. The normalised relative electronic-state transition probabilities for production of ionic states in Penning ionization and photoionization are reported together with energy shifts (ΔE values) for He*(23S) Penning ionization. The cross-section for Penning ionization to lower states of NO2+ is extremely low as has been observed in other open shell molecules such as NO and O2. 相似文献
3.
B. Carré G. Spiess J.M. Bizau P. Dhez P. Gérard F. Wuilleumier J.C. Keller J.L. Le Gouët J.L. Picqué D.L. Ederer P.M. Koch 《Optics Communications》1984,52(1):29-34
The first observation, by electron spectrometry, is reported in laser-excited sodium vapor of the primary low energy electrons produced by associative ionization and by Penning ionization of sodium atoms in highly excited n1 states. The sequential heating of these primary electrons has been observed in 1, 2 or 3 superelastic collisions with Na(3p) atoms. The variation of associative ionization was measured as a function of the excited state density by using inner-shell photoionization produced by synchrotron radiation. Finally, an associative ionization cross section of 3.8 X 10-17 cm2 and a Penning ionization cross section for the 5s state of 1.1 X 10-12 cm2 were found (within 50% uncertainty) for an oven temperature of 520 K. 相似文献
4.
M. Yamazaki N. Kishimoto K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):47-57
Collisional ionization of styrene (phenylethylene), 2-vinylpyridine, and
4-vinylpyridine with metastable He*(23S) atoms were studied by means of
collision-energy/electron-energy resolved two-dimensional Penning
ionization electron spectroscopy. Collision energy dependence of partial
ionization cross-sections, which reflects the anisotropic interactions
between a He*(23S) atom and the target molecules, indicates that
attractive interaction for the out-of-plane access of a He*(23S) atom
to phenyl group is stronger than that for the out-of-plane access to vinyl
group. Moreover, it was found for vinylpyridines that the attractive
interaction around π electrons became weaker than that for styrene, and
that the attractive interaction for the in-plane access to the nitrogen atom
is stronger than that for out-of-plane π-directions. However, in
2-vinylpyridine, the hydrogen atom of vinyl group prevents a He*(23S)
atom from approaching to the nitrogen atom along in-plane directions, and
thus the attractive interactions around the nitrogen atom were shielded by
the vinyl group. The experimentally observed anisotropic interactions were
qualitatively supported with ab initio model interaction potential calculations
between a Li (He*(23S)) atom and the target molecule. Concerning with
electronic structures of investigated molecules, the assignment of Penning
ionization electron spectrum for 4-vinylpyridine was discussed on the basis
of different behavior of collision-energy dependence of partial ionization
cross-sections, and the satellite ionization band in Penning ionization
electron spectra was also reported for styrene. 相似文献
5.
A strong optogalvanic effect has been observed in a negative glow of a miniature neon discharge lamp using tunable pulse dye laser pumped by a copper vapor laser. A comparative study on temporal evolution of optogalvanic signal in a positive and negative dynamic resistance region of the discharge is described. Dye laser beam was tuned to various neon transitions 1si → 2pj (Paschen notations) within 570-617 nm wavelength range. Anomalous behavior of optogalvanic signal was observed at 588.2 nm for (1s5 → 2p2) neon transition at low discharge current (<220 μA). This anomalous behavior is the attributes of damped oscillations of optogalvanic signal that correlate with negative dynamic resistance (dV/di < 0) of the discharge. Penning ionization at low discharge current and small energy mismatch is assumed to be the main cause of the negative dynamic resistance. Penning ionization process has been explained by resonantly ionizing energy transfer via collisions between neon buffer gas atoms in the lowest metastable state (1s5) and electrode sputtered atoms in ground state using their partial energy level diagram. 相似文献
6.
Using a crossed-beam apparatus with a double hemispherical electron spectrometer, we have studied the spectrum of electrons released in thermal energy ionizing collisions of metastable He*(23S) atoms with ground state Yb(4f14 6s2 1S0) atoms, thereby providing the first Penning electron spectrum of an atomic target with 4f-electrons. In contrast to the Hel (58.4 nm) and NeI (73.6/74.4 nm) photoelectron spectra of Yb, which show mainly 4f- and 6s-electron emission in about a 5:1 ratio, the He*(23S) Penning electron spectrum is dominated by 6s-ionization, accompanied by some correlation-induced 6p-emission (8% Yb+(4f14 6p 2P) formation) and very little 4f-ionization (?2.5%). This astounding result is attributed to the electron exchange mechanism for He*(23S) ionization and reflects the poor overlap of the target 4f-electron wavefunction with the 1s-hole of He*(23S), as discussed on the basis of Dirac-Fock wave functions for the Yb orbitals and through calculations of the partial ionization cross sections involving semiempirical complex potentials. The presented case may be regarded as the clearest atomic example for the surface sensitivity of He*(23S) Penning ionization observed so far. 相似文献
7.
Using helium metastable atoms (21S, 23S), the Penning ionization of C2H4 has been studied using a high resolution electrostatic electron analyzer. The Franck—Condon envelope for the ground state of C2H4+ (X2B3u) is found to be the same for He* (23S) Penning ionization and 584 Å photoionization. The ΔE shift values and the relative electronic transition probabilities are reported for four ionic states. Unusually large differences have been found for the relative electronic transition probabilities for Penning ionization and photoionization. 相似文献
8.
H. Hotop E. Kolb J. Lorenzen 《Journal of Electron Spectroscopy and Related Phenomena》1979,16(3):213-243
Using two intense thermal energy He(23S) sources of different temperatures (≈400 and ≈ 1000 K, resp.) and a transmission-calibrated electron energy analyzer with about 30meV resolution, the dependence of He(23S) Penning ionization electron spectra on collision energy for the target species Ar, N2, NO, O2, N2O and CO2 have been studied. The energy shifts of the Penning electron energy distributions and the branching ratios for the population of different electronic states in the molecular ions are determined quantitatively and compared for the two different collision temperatures. These results and the shapes of the observed Penning electron energy distributions are discussed in the light of current models for the Penning procen; the observed temperature dependences are correlated with the nature of the ionized orbitals in cases of only one entrance channel (closed shell targets) and, in addition, to the existence of qualitatively different entrance channels (open shell targets). 相似文献
9.
The He*(21S, 23S) Penning ionization electron spectra of HCN, (CN)2, CH3CN, BrCN and ICN are compared to the corresponding 584 Å photoelectron spectra. Large differences are observed for the relative populations of the ionic states of the various molecules when Penning ionization is compared to photoionization. For these molecules, the ratio of the normalized relative populations of states corresponding to removal of π bonding and nitrogen lone pair electrons is significantly greater for 584 Å photoionization than for He*(23S) Penning ionization. Some unidentified chemi-ionization processes are observed for (CN)2, BrCN and ICN. 相似文献
10.
D.S.C. Yee W.B. Stewart C.A. McDowell C.E. Brion 《Journal of Electron Spectroscopy and Related Phenomena》1975,7(2):93-117
A high resolution electrostatic electron analyser has been used to study Penning ionization electron spectra of H2, HD, D2, N2, CO, NO and O2 using helium metastable atoms (21S, 23S). Results for H2, N2 and CO are in good agreement with other work. New data are presented for HD, D2, NO and O2. The Penning electron spectra are also compared to the 584 Å photoelectron spectra obtained in the same apparatus. The relative vibrational intensifies for the given electronic bands indicate that in most cases Franck—Condon factors for Penning ionization and photoionization are very similar. However for the O2+(X2Πg) band, the (23S) Penning electron and photoelectron spectra show significant differences in the Franck—Condon envelopes This perturbation of the envelope for the Penning ionization may be explained by a competing autoionization process. The relative electronic transition probabilities are in many cases found to be different for Penning ionization and photoionization. 相似文献
11.
Electronically excited argon in the 3 P 1 state was generated in a flow system by resonance absorption of the λ=106·7 nm emission line. This photochemical source is particularly convenient for kinetic studies since Ar(3 P 1) alone is produced in the primary exciting step. Energy transfer from excited argon may lead to Penning ionization: This process has been studied for M=NO and M=O2(1Δ g ). Relative concentrations of Ar* were estimated from the Penning ion current, and it is shown that Ar* is probably in the initially excited 3 P 1 state and not in the metastable 3 P 2 state. Kinetic studies showed that Penning ionization of NO occurs for about one in every five gas kinetic collisions with Ar(3 P 1). The Penning process can only compete effectively with radiative loss of Ar(3 P 1) as a result of extensive imprisonment of resonance fluorescence. Penning ionization of O2(1Δ g ) is shown to proceed at nearly the same rate as ionization of NO. The decrease in Penning ion current on addition of a quenching gas, such as N2 or O2, is used to derive rate constants for the quenching process relative to the rate of quenching by NO. Estimated absolute rate constants are presented in a table. 相似文献
12.
13.
The electron spectra resulting from thermal collisions of He*(21S, 23S) metastable atoms with HCHO, CH3CHO, CH3COCH3, HCOOH and CH3COOH, are compared to the respective 584-Å photoelectron spectra. An analysis of the Penning electron band shape and the position of the peak maximum for the ground-state ions suggest there are significant differences in the Franck-Condon factors when compared with photoelectron spectra. This may be ascribed to modifications of the target potential-energy surfaces. It is also observed that the relative populations of the ionic states differ appreciably for Penning ionization and photoionization. 相似文献
14.
Wolfgang Goy Volkmar Kohls Harald Morgner 《Journal of Electron Spectroscopy and Related Phenomena》1981,22(3):383-386
We have investigated the Penning ionization of NO2(2A1) by He(23S) by means of electron—ion coincidence measurements. It is possible to identify two entrance channels. The quartet state is essentially repulsive and gives rise to an electron energy spectrum similar to that found in photoionization. The doublet entrance channel is strongly attractive with a well depth De of 4.8 {?0.3+0.1 eV. Ionization out of this channel leads to very broad features in the electron energy spectrum. 相似文献
15.
《Journal of Electron Spectroscopy and Related Phenomena》2005,142(3):283-293
Collision-energy/electron-energy-resolved two-dimensional Penning ionization electron spectroscopy (2D-PIES) has been used to study outer characteristics of molecules. Anisotropic potential energy surfaces for collisional ionization of molecules with a metastable helium atom He*(23S) have been determined starting from ab initio model potentials via optimization based on trajectory calculations. Since ionization widths in the theoretical model of Penning ionization are functionals of target molecular orbitals, outer electron distributions of molecular orbitals can be determined via optimization procedures of calculated ionization cross-sections by trajectory calculations with respect to observed 2D-PIES data. 相似文献
16.
Kellerbauer A. Blaum K. Bollen G. Herfurth F. Kluge H.-J. Kuckein M. Sauvan E. Scheidenberger C. Schweikhard L. 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):53-64
For a detailed study of the accuracy of the Penning trap mass spectrometer ISOLTRAP all expected sources of uncertainty were
investigated with respect to their contributions to the uncertainty of the final result. In the course of these investigations,
cross-reference measurements with singly charged carbon clusters 12C+
n were carried out. The carbon cluster ions were produced by use of laser-induced desorption, fragmentation, and ionization
of C60 fullerenes and injected into and stored in the Penning trap system. The comparison of the cyclotron frequencies of different
carbon clusters has provided detailed insight into the residual systematic uncertainty of ISOLTRAP and yielded a value of
8×10-9. This also represents the current limit of mass accuracy of the apparatus. Since the unified atomic mass unit is defined
as 1/12 of the mass of the 12C atom, it will be possible to carry out absolute mass measurements with ISOLTRAP in the future.
Received 7 June 2002 Published online 6 November 2002
RID="a"
ID="a"e-mail: a.kellerbauer@cern.ch
RID="b"
ID="b"Current address: Centre de Physique des Particules de Marseille, 13288 Marseille Cedex 9, France. 相似文献
17.
A. Salmoun R. Brédy J. Bernard L. Chen S. Martin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):55-61
Electron capture processes in collision between slow
X7+ (X = N, O and Ne) ions and C60 fullerene have been
investigated using coincident measurements of the number n of ejected
electrons, the mass and charge of the multicharged C60
r+ recoil ions and their fragments Cm
i+ and the final charge state of the
outgoing projectiles X(q-s)+ (
). The
collision velocity is about 0.4 a.u. The partial cross-sections σr
s , corresponding to r electrons transferred to the projectile with only s electrons stabilized, have been measured. Cross-sections
for collisions “inside” and those “outside” the C60
cage have been separated by analyzing the kinetic energy of the outgoing
projectile. The mean final charge state for frontal collisions has been
measured to 3.1, 2.6 and 2.5 for N7+, O7+ and Ne7+
respectively. These results show the importance of the core effect on the
stabilisation processes of captured electrons. 相似文献
18.
S. Tomita J.S. Forster P. Hvelplund A.S. Jensen S.B. Nielsen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):119-122
We have measured attenuation cross sections and fragmentation cross sections for protonated water clusters H(H2O)n
+ (n = 1 to 100) colliding with noble gas atoms (He and Xe) at a laboratory energy of 50 keV. In collisions with He, a transparency
effect in the attenuation cross section was observed. For the case of fragmentation in collisions with Xe, a strong enhancement
of small clusters was observed which we attribute to multifragmentation.
Received 30 November 2000 相似文献
19.
N. Kishimoto M. Matsumoto E. Matsumura K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):75-84
Stereodynamics in ionization of toluene and o-, p-chlorotoluenes by collision
with He*(23S) metastable atoms were investigated by two-dimensional
collision-energy/electron-energy-resolved Penning ionization electron
spectroscopy. Anisotropic interactions around the molecule were studied by
the collision energy dependence of partial ionization cross-sections
(CEDPICS) as well as model potential calculations, and shielding effect by
the methyl group was observed in CEDPICS for ionization from Cl lone-pair
orbitals of o-
chlorotoluene. Attractive interaction with He*(23S)
around the π orbital region was found to be larger for toluene rather
than o-, p-
chlorotoluenes. Exterior electron density (EED) calculation of
partial ionization cross-sections in Penning ionization and negative CEDPICS
for ionization band observed in ca. 4 eV in electron energy indicated that
π-2π+1 shake-up state was observed in
Penning ionization electron spectroscopy of toluene. 相似文献
20.
M. Sabidó J. de Andrés J. Sogas J. M. Lucas M. Albertí J. M. Bofill I. Rabadán A. Aguilar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):63-70
The dynamics of collisional processes between Mg atoms and caesium ions is studied using the hemiquantal (HQ) approach with
special attention to the collisional channels leading to Mg(3 1P) and Cs(6 2P) states, for which the corresponding emission excitation functions have been previously measured in our laboratory. The
radial and angular non-adiabatic couplings between the manifold of quasimolecular states have been determined using an ab
initio configuration interaction calculation. The cross-sections for the different channels, as a function of the laboratory
collisional energy, are compared with experimental values. The dynamical calculations indicate that, for the inelastic processes
considered, the range of relevant impact parameters is small, active collisions being of the head-on type.
. 相似文献