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1.
Shoaib Ahmad 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(3):349-354
Formation of the regenerative soot is the process of recycling and introduction of the cathode deposited carbon clusters into
the discharge. The agglomerates of carbon clusters on the cathode release their constituents into the plasma that goes from
the pure sputtering mode to the sooting one. The process of the regeneration of the soot that emits large carbon clusters
is discussed by evaluating the state of the carbon vapour by using the characteristic line emissions from the discharge.
Received 17 April 2001 and Received in final form 13 June 2001 相似文献
2.
Shoaib Ahmad 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):309-318
The mechanisms and processes of the formation of the regenerative soot in a graphite hollow cathode discharge that produces
and emits carbon clusters are presented. Mass spectrometry with a specially designed E×B velocity filter analyzes the entire range of the charged clusters from C
1 to ∼C
4300. The state of the carbon vapour within the source is evaluated by using the characteristic line emissions from the carbonaceous
discharge whose formative mechanisms depend upon the kinetic and potential sputtering of the sooted cathode. The carbonaceous
discharge generates atomic and ionic C and its clusters C
m (m≥ 2), noble gas metastable atoms and ions, energetic electrons and photons in the cavity of the graphite hollow cathode. The
parameters of soot formation and its recycling depend critically on the discharge parameters, the geometry of the hollow cathode
and 3D profile of the cusp magnetic field contours.
Received 2nd July 2001 and Received in final form 10 September 2001 相似文献
3.
J. Martinez C. T. Whelan H. R.J. Walters 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):409-414
We consider (e,2e) processes on the 2s and 2p shells
of argon and magnesium. We present triple differential cross
sections in coplanar asymmetric geometry calculated in the Plane
Wave Born, 1st Born and Distorted Wave Born approximations. We show
that the currently available relative experiments can not easily
distinguish between these approximations. We make proposals for
relative experiments where the difference between these approaches
can be more readily observed. 相似文献
4.
A. Gopalan J. Bömmels S. Götte A. Landwehr K. Franz M.-W. Ruf H. Hotop K. Bartschat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):17-29
A novel electron scattering apparatus for high resolution studies of angle-differential elastic and inelastic electron scattering
from atoms and molecules in the gas phase is described and its performance characterized. It combines a laser photoelectron
source, a triply differentially pumped collimated supersonic beam target (half angle 0.015 rad, background to beam density
ratio < 0.01), and several electron multipliers for simultaneous detection of elastically scattered electrons and metastable atoms (or
molecules) due to inelastic scattering. In detailed test measurements of the yield for the production of metastable He*(23S1) atoms around its threshold, the dependence of the overall energy width on various experimental parameters has been investigated.
So far a resolution down to 7 meV (FWHM) has been obtained. Under such conditions we have investigated the profile of the
He- (1
s
2
s
2
2
S
1/2
) resonance at the scattering angles 22
°
, 45
°
, and 90
°
. From a consistent fit of the measured profiles by resonant scattering theory we determine a new value for the resonance
energy ( E
r
= 19.365(1) eV) and an accurate resonance width ( Γ = 11.2(5) meV). These results are consistent with the previously recommended values.
Received 23 July 2002 Published online 29 October 2002
RID="a"
ID="a"e-mail: hotop@physik.uni-kl.de
RID="b"
ID="b"Permanent address: Department of Physics and Astronomy, Drake University, Des Moines, IA 50311, USA. 相似文献
5.
S. Bhattacharya K. B. Choudhury N. C. Deb C. Sinha K. Roy A. Z. Msezane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):335-338
A one channel distorted wave approximation has been used to calculate the ionization cross section for the 3s electron of
Na
atom by alpha particle impact. For a consistency check we have also run the standard CDW-EIS code of McSherry et al. [Comput.
Phys. Commun. 155, 144 (2003)]
and found reasonable agreement in the high energy region among the present results, the CDW-EIS results and the classical
trajectory Monte Carlo (CTMC)
calculations. It is also found that the present
results tend to agree qualitatively with the low energy measurement of Knoop et al. [J. Phys. B 38, 1987 (2005)] at as low as 10 keV amu-1,
although the present theoretical approach is expected to be suitable in the high energy area. This qualitative agreement in
the low energy region is
attributed to the partially correlated ground state wave function used in the present calculation. 相似文献
6.
V.V. Klimov M. Ducloy V.S. Letokhov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):133-148
The frequency shift and linewidth variation of an atomic oscillator placed next to a prolate dielectric or metal spheroid
are found within the framework of the classical approach. Both the frequency shift and linewidth are shown to be substantially
dependent on the location of the atom and the form of the nanospheroid and capable of reaching very high values near the surface
of the nanospheroid under plasmon (polariton) resonance conditions. The predictions are compared with those found for spherical
and cylindrical geometries. The prolate spheroid is treated as a model of a needle tip in apertureless optical scanning microscopy.
Effects of sharpness of interaction between the nanospheroid tip and atoms are considered.
Received 2 January 2002 and Received in final form 3 April 2002 Published online 28 June 2002 相似文献
7.
E. Träbert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,26(2):147-149
The analysis and interpretation of the data presented by S. Ahmad [Eur. Phys. J. D 22, 189 (2003)] are shown to be inconsistent, and are in conflict with established atomic physics.Received: 11 July 2003, Published online: 30 September 2003PACS:
32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
8.
M. Boustimi J. Baudon M. Ducloy J. Reinhardt F. Perales C. Mainos V. Bocvarski J. Robert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):141-144
The transmission of metastable argon atoms through nano-slit or micro-slit gratings is studied by use of time of flight and
angular analysis. This transmission departs from the simple geometric one essentially by two ways: (i) the elastic or diagonal
part of the van der Waals (vW) interaction with the solid causes an angular narrowing of the emerging beam; (ii) the off-diagonal
vW interaction induces the exothermal fine structure transition 3
P
0↦3
P
2 (ΔE = 175 meV) leading to large scattering angles; the resulting angular distribution is very sensitive to the roughness of the
surface in the direction of the depth. An extension of these experiments to transversally coherent beams is proposed. It should
be considered as a first step towards a new type of interferometer in which the inelastic diffraction makes the gratings work
as beam splitters or mirrors.
Received 6 July 2001 and Received in final form 17 September 2001 相似文献
9.
C. Marinelli K.A. Nasyrov S. Bocci B. Pieragnoli A. Burchianti V. Biancalana E. Mariotti S.N. Atutov L. Moi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):231-235
The light induced atomic desorption effect, known as LIAD, is observed whenever Pyrex cells, coated with siloxane films and
containing alkali atoms, are illuminated. LIAD is a non-thermal phenomenon and it can be observed even with very weak light
intensities. We show that the simultaneous contribution to the photo-emission of atoms adsorbed both at the film surface and
within the film must be taken into account in order to fit the experimental data. We demonstrate that both the desorption
efficiency and the diffusion coefficient of the alkali atoms embedded in the dielectric film depend on the desorbing light
intensity. These features characterize a new class of photo-induced phenomena whose analysis gives new insights in the comprehension
of the atom-surface interaction and of the atom-bulk diffusion and opens interesting perspectives for applications.
Received 27 April 2000 and Received in final form 15 September 2000 相似文献
10.
11.
J. B. Boffard M. F. Gehrke M. E. Lagus L. W. Anderson C. C. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(2):193-198
This paper describes a method for reducing the influence of cascades on the measurement of electron excitation cross sections
using the optical method and a fast beam atomic target. By using a fast beam of target atoms one can reduce the influence
of cascades on a measurement, and estimate the cascade contribution to the excitation signal.
Received 19 April 1999 and Received in final form 10 August 1999 相似文献
12.
H. Deutsch K. Becker T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):283-287
We report calculations of the electron-impact ionization cross-sections of selected dimers (homonuclear diatomic molecules)
and trimers (homonuclear triatomic molecules) using a method which relies only on macroscopic quantities in conjunction with
a “defect concept”. The empirically determined defect describes the deviation of the cluster (dimer, trimer) cross-sections
from a simple linear dependence on the cluster size. We compare the calculated cross-sections to experimental data for the
dimers S2 and F2 and the trimer O3 and we present predictions for the ionization cross-sections of Br2, I2, C2 and C3 for which no experimental data are available. Lastly, we extend the method to the calculation of ionization cross-sections
for the fullerenes C60 and C70.
Received 6 December 1999 and Received in final form 10 April 2000 相似文献
13.
A. Qayyum M.N. Akhtar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):181-184
Light emission during sputtering of graphite targets with 1–10 keV Ne+, Kr+ and Xe+ beams has been investigated in the 180-600 nm wavelength range. Beside the characteristic lines of sputtered C1 and C1
+, a continuum superimposed with a number of broad structures was observed in the 250-520 nm range, and having a maximum at
386 nm. Mass analysis of the sputtered flux confirmed the presence of negative carbon clusters C
m
-
, C2
- being the dominant one. Ion beam parameters i.e. ion mass, energy, current density and ion dose were varied to identify the origin of the continuum emission. On the basis
of the experimental results, it is suggested that the continuum is predominantly due to the overlapping of various band systems
of sputtered C2 with a small contribution from the heavier sputtered carbon clusters Cm (m>2).
Received 24 September 1999 and Received in final form 11 February 2000 相似文献
14.
N. Verma A. K.S. Jha M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):235-241
Electron excitation collision strengths for the transitions from the ground
state to the fine-structure levels of the 3s23p53d and
3s23p63d configurations in Ni XI are calculated using the
Breit-Pauli R-matrix method. Configuration interaction wavefunctions have
been used to represent the target states. The relativistic effects are
incorporated in the Breit-Pauli approximation by including one-body mass
correction, Darwin, and spin-orbit interaction terms in the scattering
equations. Collision strengths are tabulated at selected energies in the
range 10 to 75 Rydberg. Effective collision strengths are determined by
integrating collision strengths by assuming a Maxwellian distribution of
electron energies. The effective collision strengths are listed over a wide
temperature range (2×104-1×107 K) applicable to
astrophysical plasmas. Our results are the only collision strengths and
effective collision strengths available for this ion. We believe that the
data calculated in this work will be useful in solar, astrophysical and
laser applications. 相似文献
15.
J. P. Santos F. Parente 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):339-350
Total ionization cross sections of neutral phosphorus, arsenic,
antimony, and bismuth atoms by electron impact are reported and
compared to the only available experimental results by Freund et al. [Phys. Rev. A 41, 3575 (1990)]. These calculations take into account the possibilities that some
target atoms used in the experiments were in metastable states close
to the ground state, the excitation-autoionization of nsnp4
excited states may be substantial, and the ions produced in
experiments may be in excited, low-lying metastable states. The cross sections for direct ionization calculations are based
on
the BEB model by Kim and Rudd [Phys. Rev. A 50, 3954 (1994)].
Plane-wave Born cross sections scaled by the method developed by Kim
[Phys. Rev. A 64, 3954 032713 (2001)] are used to determine the
contributions from excitation-autoionization. The combination of the BEB model and the scaled Born cross sections
is in agreement with the experimental data by Freund et al. These theoretical data are useful to experimentalists and can
be
used to complete data tables needed for plasma or astrophysical
studies. 相似文献
16.
K. Andersson D. Hanstorp A. Neau S. Rosén H.T. Schmidt R. Thomas M. Larsson J. Semaniak F. Österdahl H. Danared A. Källberg A. Le Padellec 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):323-328
Electron Impact Single Detachment (EISD) of F- has been studied using the heavy ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm, Sweden. F- ions stored in the ring were merged with an electron beam in one of the ring sections. Neutral F atoms produced in the EISD
process were detected in the zero-degree direction using a surface barrier detector. The threshold for the detachment process
was found to be around 7.6 eV, thus more than twice the binding energy of F-. The cross-sections increased smoothly up to 55 eV where it reached a maximum of 1.9×10
-16
cm
2
. At higher energies a slow decrease of the cross-section was observed, which follows the energy dependence predicted by the
Bethe-Born approximation. The experiment showed that CRYRING can be used favourably for studies of anions, and several experiments
are forthcoming.
Received 14 June 2000 and Received in final form 11 September 2000 相似文献
17.
J.H. Xu F. Mango G. Alzetta R.A. Bernheim 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):243-246
Alkali metals adsorbed to surface films of the polymer poydimethylsiloxane (PDMS) have been shown to exhibit a unique photodesorption
behavior, characterized by a frequency threshold and high efficiency. In this work, the temperature dependence of the photodesorption
yields of Na and Na
2
from PDMS surfaces were measured between room temperature and 183 K. Over most of the temperature range, the yields exhibited
an Arrhenius behavior characterized by thermal activation energies of 0.36 eV and 0.34 eV for Na and Na
2
, respectively. These values are suggestive of a surface diffusion as one of the elementary steps in the photodesorption mechanism.
Moreover, the similarity of the two values indicates that the same elementary step applies to the desorption of both Na and
Na
2
.
Received 23 April 1999 and Received in final form 15 July 1999 相似文献
18.
J.-G. Wang T.-Q. Chang C.-Z. Dong T. Kato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):167-171
A simplified relativistic configuration interaction method is used to study the dielectronic satellite transition processes.
In this method, the infinite resonant doubly excited states can be calculated, and furthermore, the whole high-n dielectronic satellite transition processes can be treated conveniently by interpolation (rather than extrapolation) in the
frame of Quantum Defect Theory. As an example, we calculate the contributions from high-n dielectronic satellites to the resonance line in helium-like iron, and the results are in good agreement with the experimental measurements.
Received: 16 April 1998 / Revised: 8 September 1998 / Accepted: 14 September
1998 相似文献
19.
Calculation of dielectronic recombination cross sections and rate coefficients for heliumlike carbon
J.-G. Wang T.-Q. Chang Y.-Z. Qu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):231-235
A simplified relativistic configuration interaction method is used to calculate the dielectronic recombination cross sections
and rate coefficients for heliumlike carbon. In this method, the infinite resonant doubly excited states can be treated conveniently
in the frame of Quantum Defect Theory. Our calculated cross sections are in agreements with the experimental measurements
except for the 1s2lnl'(n=6,7) resonances. The total energy-integrated cross sections and rate coefficients over all dielectronic resonances are in
agreements with the experimental measurements within percent.
Received: 7 July 1997 / Revised: 7 October 1997 / Accepted: 8 December 1997 相似文献
20.
E. Träbert U. Staude P. Bosselmann K.H. Schartner P.H. Mokler X. Tordoir 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):117-123
N
=3, intercombination transitions in Al-like ions of Au have been studied by time-resolved EUV spectroscopy of foil-excited ion
beams. Wavelengths and lifetimes are compared to the available relativistic calculations. The theoretical data are found to
be useful for guidance, but of clearly insufficient precision, in particular for the transition probabilities.
Received: 23 February 1998 / Accepted: 5 March 1998 相似文献