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51.
S. Cohen M. Aymar A. Bolovinos M. Kompitsas E. Luc-Koenig H. Mereu P. Tsekeris 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):165-180
The even parity 5
pnpJ
= 0, 1 and 2 doubly excited autoionizing states of strontium were investigated both experimentally and theoretically. Sr atoms
in an atomic beam were excited through the two-step Isolated Core Excitation (ICE) scheme 5s2
1
S
0
-λ
1
→ 5
sn'p
1
P
1
(
n'
= 12-16)-λ
2
→ [5
p
3/2
np
]
J
. The final ICE transition probes the [5
p
3/2
np
]
J
resonances. However, the [5
p
1/2
np
]
J
series below the 5
p
1/2
threshold were excited also due to their mixing with the [5
p
3/2
np
]
J
perturbers. An extended energy region was covered below and above the 5
p
1/2
ionization limit by saturating the central ICE lobe and recording as many as possible “red” and “blue” secondary lobes. J identification was achieved by using mutually parallel and perpendicular linear polarizations of the laser beams. The ICE
spectra were compared to those obtained by employing a two-step excitation scheme using the bound 4
d
5
p
1
P
1
valence state as an intermediate one. Final identification for very complex structures was achieved after comparison with
theoretical energy level positions and excitation profiles produced by the R-matrix method combined with the multichannel quantum defect theory (MQDT) method. The agreement between theoretical and observed
structures is quite satisfactory.
Received 31 May 2000 相似文献
52.
Electron photodetachment of trapped doubly deprotonated angiotensin peptides. UV spectroscopy and radical recombination 总被引:1,自引:0,他引:1
R. Antoine L. Joly A. R. Allouche M. Broyer J. Lemoine Ph. Dugourd 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(1):117-124
Trapped doubly deprotonated peptides are subjected to electron detachment when irradiated by a UV light. Electron photodetachment
experiments as a function of the laser wavelength and laser fluence have been performed on two variants of angiotensin. The
electron detachment yield was used to monitor the excited electronic spectrum of the trapped ions. Furthermore, the electron
loss leads to the formation of radical ions. The radical recombination after collision activation is discussed. 相似文献
53.
K.?Koyasu M.?Niemietz W.?Westh?user G.?Gantef?r 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(1):59-62
The decay path of an Ag8(O2)- cluster photoexcited by a 3.1 eV photon is elucidated using time-resolved photoelectron spectroscopy. Photoabsorption results
in the formation of an excited state giving rise to a peak in the photoelectron spectra with well-resolved vibrational finestructure.
With a lifetime of about 100 fs this bound state decays into an anti-bonding state which dissociates into O2 and Ag8- on a timescale of 10 ps. In the photoelectron spectra, this corresponds to a broad maximum shifting gradually towards higher
binding energy while the O2 and Ag8- separate. Finally, the spectrum of bare Ag8- appears. This process is unique to small clusters, because on metal surfaces excited state lifetimes are too short to allow
for direct dissociation. 相似文献
54.
L.A.A. Nikolopoulos Takashi Nakajima P. Lambropoulos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):297-304
Calculations of intense field (around 1016 W/cm2) single- and double-ionization processes in helium at XUV wavelengths are presented. The laser wavelength is chosen near
the | 2s2p
1
P autoionization structure and the dynamics are explored. Single and double ionization yields, as well as the photoelectron
energy spectrum for photon energies around the autoionization structure are calculated. In the case of a pulse of few femtoseconds
duration, no significant enhancement of the double ionization yield has been found in tuning the photon frequency around the
peak of the resonance. It is also shown that in the case of a long pulse (and hence narrow compared with the relevant autoionization
width), the branching ratio of double to single ionization yield can be relatively enhanced by tuning to the absorption minimum
of the resonance.
Received 19 February 2002 / Received in final form 2 May 2002 Published online 19 July 2002 相似文献
55.
P.-A. Hervieux A. Benabbas V. Halté J.-Y. Bigot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):185-189
The electronic temperature dependence of the optical
absorption of silver nanoparticles is investigated in the
framework of the time-dependent local-density approximation at
finite temperature. Below the spectral region of interband
transitions, we have found that the electronic temperature leads
to a broadening and spectral shift of the surface plasmon
resonance. The calculated differential transmission is in good
agreement with recent experimental measurements obtained with
time resolved pump-probe techniques. 相似文献
56.
N. Chandra S. Sen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(4):457-480
This communication presents a theoretical study of the angular distribution of one or both of the two electrons emitted in
one-photon, one-step double ionization of a linear molecule. Experiments which do or do not detect spin of the photoelectrons
have been considered. Effects of molecular rotation on double photoionization have been studied in both Hund's coupling schemes
(a) and (b) by using parity-adapted states. Selection rules obtained in this paper are very different from those derived earlier
for single photoionization and for Auger decay following the absorption of a photon in a rotating linear molecule. It is shown
that complete specification of the spin-unresolved and of spin-resolved angular distributions of both photoelectrons require,
respectively, three and seven parameters which depend, among other things, on their energies as well as directions of emission.
The approach developed in this paper has been used to analyze spin-unresolved double photoionization in the shell of the molecule. The angular distribution is quite different depending on whether or not molecular rotation has been taken into
account. Also, it is found to change significantly for different rotational transitions. Effects of electron-electron correlation
are clearly manifested even in non-coincident, both rotationally resolved--as well as unresolved--double photoionization.
Received: 7 August 1998 相似文献
57.
利用多通道量子数亏损理论对钾的一价离子的3p光吸收光谱进行了分析,计算并预言了80多个实验上未观察到的能级以及相应能级的朗德g因子,对于实验上未区分的能级做了重新的认定,预言了自电离区的3p5ns(1/2,1/2)n=17-21的能级,讨论了通道之间的干扰情况。 相似文献
58.
S.I. Themelis Y. Komninos C.A. Nicolaides 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):277-293
This paper discusses theory and results on 1P0 doubly excited states (DES) in He and in H- of very high excitation, up to the N
= 25 manifold. Our calculations employed full configuration interaction (CI) with large hydrogenic basis sets and produced correlated
wavefunctions for the four lowest roots at each hydrogenic manifold by excluding open channels and the small contribution
of series belonging to lower thresholds. The suitability of the hydrogenic basis sets for such calculations is justified,
apart from their practicality, by the fact that, by computing from them natural orbitals, the results were shown to be the
same with those of earlier multiconfigurational Hartree-Fock (MCHF) calculations on low-lying DES. In total, 160 states were
computed, most of them for the first time. Their energy spectrum should be of use to possible future photoabsorption experiments.
For certain low-lying DES up to N
= 13, for which previous reliable results are available, comparison of the calculated energies shows good agreement. The correlated
wavefunctions contain systematically chosen single and double excitations from each hydrogenic manifold of interest. From
their analysis, we determined the “goodness" of different quantum numbers and the geometry (average angles and radii) as a
function of excitation. For the Sinano lu-Herrick (
K
,
T
) classification scheme, whose basis is a restricted CI with hydrogenic functions and which has thus far been tested only on
low-lying DES, we established that, whereas T remains a good index as energy increases, K does not. Consequently, a more flexible than K quantum number is needed in order to account for most of the additional correlation. This number, represented by F
=
N
-
K
- 1, where N and K are not good numbers anymore, produces consistently a much higher degree of purity than the (
K
,
T
) scheme does, especially as N increases and as the relative significance of various virtual excitations due to electron correlation increases. Among the
four states of each manifold, in all cases in H- and in most cases in He, the three are of the intrashell type and one is of the intershell type with (
F
,
T
) = (0, 0). The lowest intrashell states and the lowest intershell states exhibit a wide angle geometry tending to 180
°
as N
↦∞.
Received 10 September 2001 and Received in final form 12 November 2001 相似文献
59.
铀原子自电离态能级测量 总被引:2,自引:1,他引:1
用三台可调谐脉冲染料激光器三步共振电离方法,测量了在49898-50880cm^-1能量区间的一些轴原子里堡态和自电离态能级位置。 相似文献
60.
S. Martin J. Bernard L. Chen A. Denis J. Désesquelles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):27-32
Resonant excitation or resonant electron scattering is a two step process in which Auger rates are involved in both steps.
First an electron is captured into a bound state and a bound electron is excited (inverse Auger effect). Then an Auger transition
leads to the emission of the electron from the ion. The corresponding cross-sections are very sensitive to the Auger rates
and allow a detailed study of the Breit interaction which is a current-current contribution to the static electron-electron
interaction. The contribution of the Breit interaction to the cross-section of resonant excitation on hydrogen-like uranium
ions is discussed and shown that it is roughly twice as large as in the case of dielectronic recombination.
Received 4 August 1999 and Received in final form 29 September 1999 相似文献