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1.
采用三台可调谐激光实施孤立实激发,分三步将处于基态的Ba原子激发到6p1/2nd(J=1,3)和6p3/2nd(J=1,3)自电离态上,获得了分别从6snd1D2(n=7—15)和6snd3D2(n=7—12) 激发而得到的6p1/2nd(J=1,3)和6p3/2nd (J=1,3)自电离光谱,重点对主量子数n较低的自电离态进行了实验研究. 通过光谱的线形拟合得到了上述能级的位置和宽度等数据,进而获得了量子亏损和约化宽度等信息. 通过对不同系列的自电离光谱的分析和比较,详细讨论了这些自电离态的光谱特征及其复杂光谱结构的成因.
关键词:
孤立实激发
组态相互作用
自电离态 相似文献
2.
M.A. Baig M. Yaseen Raheel Ali Ali Nadeem S.A. Bhatti 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(2):201-209
We report new measurements on laser-assisted molecular dissociative sequential excitation and ionization spectra of strontium
vapor. A single Nd:YAG pumped dye laser in conjunction with an atomic beam apparatus have been used to investigate the even
parity 5snd
3,1
D
2
Rydberg series resulting from the 5s5p
1
P
1
resonance level. The relative intensities changes among the 5snd
3
D
2
and 1
D
2
Rydberg series are attributed to the interactions with the 4d6s
1,3
D
2
perturbers, respectively. The interchannel interactions between the 5snd
1
D
2
series and the 4d6s
1
D
2
level and among the 5snd
3
D
1,2,3
series and the 4d6s
3
D
1,2,3
intruders have been separately parameterized using the two-channel quantum defect theory.
Received: 10 September 1998 / Received in final form: 16 December 1998 相似文献
3.
M. A. Baig S. Mahmood M. A. Kalyar M. Rafiq N. Amin S. U. Haq 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):9-16
We report new measurements of the oscillator strengths of the 3p
2P3/2 ↦nd 2D5/2, 3/2 and 3p 2P1/2 ↦
nd 2D3/2 Rydberg transitions of sodium using a thermionic diode ion
detector in conjunction with the Nd:YAG pumped dye lasers. The ns
2S1/2 and nd 2D5/2,3/2 Rydberg series have been recorded
via two-step excitation, from the 3p 2P3/2 and 3p 2P1/2
intermediate states. Employing the saturation technique, the photoionization
cross sections from the 3p 2P3/2 and 3p 2P1/2 intermediate states at the first ionization threshold are determined as 7.9(1.3) Mb and 6.7(1.1) Mb respectively. The f-values
of the Rydberg transitions are calibrated with the photoionization cross section measured at the first ionization threshold
and compared with the earlier data. 相似文献
4.
T. Halfmann K. Böhmer L.P. Yatsenko A. Horsmans K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):113-123
We report the observation of pronounced coherent population trapping and dark resonances in Rydberg states of xenon. A weak
two-photon coupling with radiation of = 250 nm is induced between the 5p6
1
S
0 ground state of xenon and state 5p
56p[1/2]0, leading to (2+1) resonantly enhanced three-photon ionization. The state 5p
56p[1/2]0 is strongly coupled by radiation with ≃ 600 nm to 5p
5
ns[J
C]1 or 5p
5
nd[J
C]1 Rydberg states with principal quantum numbers n in the range 18 ?n? 23 and with the rotational quantum number of the ionic core J
C = 1/2 or J
C = 3/2. The ionization is monitored through observation of the photoelectrons with an energy resolution ΔE = 150 meV which is sufficient to distinguish the ionization processes into the two ionization continua. Pronounced and robust
dark resonances are observed in the ionization rate whenever is tuned to resonance with one of the ns- or nd-Rydberg states. The dark resonances are due to efficient population trapping in the atomic ground state 5p6
1
S
0 through the suppression of excitation of the intermediate state 5p
56p[1/2]0. The resolution is sufficient to resolve the hyperfine structure of the ns-Rydberg levels for odd xenon isotopes. The hyperfine splitting does not vary significantly with n in the given range. Results from model calculations taking the natural isotope abundance into account are in good agreement
with the observed spectral structures. Pronounced dark resonances are also observed when the dressing radiation field with
is generated from a laser with poor coherence properties. The maximum reduction of the ionization signal clearly exceeds
50%, a value which is expected to be the maximum, when the dip is caused by saturation of the transition rate between the
intermediate and the Rydberg state due to incoherent radiation. This work demonstrates the potential of dark resonance spectroscopy
of high lying electronic states of rare gas atoms.
Received 7 May 2000 and Received in final form 25 June 2001 相似文献
5.
M. Stellpflug M. Johnsson I.D. Petrov T. Halfmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):35-42
We have examined the autoionization spectrum of xenon by resonantly enhanced three-photon ionization (2 + 1 REMPI) involving
intermediate states 5p
56p[J = 0, 2]. The properties of the observed autoionization resonances change significantly with the choice of the intermediate
state. For ionization via an intermediate state with predominantly 5p
5(2P3/2) core character, a strong continuum with embedded window-type 5p
5(2P 1/2)nd'-autoionization resonances is observed. For intermediate states, predominantly with 5p
5(2P1/2) core character, both 5p
5(2P 1/2)nd'- as well as 5p
5(2P 1/2)ns'-resonances are present in the spectrum as overlapping, nearly symmetric peaks on a rather weak continuum. Calculations confirm
the significant dependence of the spectral lineshapes upon the excitation pathway to the autoionizing state. The ionization
data are compared with spectra obtained by monitoring third-harmonic generation via autoionizing states without resonant excitation of intermediate states. These spectra also exhibit the signature of both
the nd'- and ns'-resonances.
Received 30 September 2002 Published online 28 January 2003
RID="a"
ID="a"Permanent address: Rostov State University of Transport Communication, 344038, Rostov-on-Don, Russia.
RID="b"
ID="b"e-mail: halfmann@physik.uni-kl.de 相似文献
6.
E. Biémont P.-D. Dumont H.P. Garnir P. Palmeri P. Quinet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):199-204
Theoretical transition probabilities have been obtained for 54 n = 3 transitions depopulating the 3s3p
1Po, 3p2
3P, 1D, 1S, 3s3d
1D, 3D and 3p3d
3Po, 3Do, 3Fo, 1Fo, 1Do, 1Po levels, including 14 transitions not yet observed. Some of these predictions have been compared with experimental lifetimes
obtained by beam-foil spectroscopy for four n = 3 levels of K7+. An excellent agreement is observed between theory and experiment for all the levels.
Received 23 January 2002 / Received in final form 23 April 2002 Published online 19 July 2002 相似文献
7.
S. Assimopoulos A. Bolovinos E. Luc-Koenig S. Cohen A. Lyras P. Tsekeris M. Aymar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):243-254
We report the even parity J
=4,5 autoionizing spectra of calcium below the 3d threshold, investigated by two-step laser excitation from the 3d4s metastables
through the 3d4p , intermediate states and subsequent optogalvanic detection. The 3d4s states are populated by electronic collisions in a d.c.
glow discharge sustained in a Ca heat-pipe. More than a hundred resonant transitions have been measured with an accuracy of
for the narrow ones using standard laser calibration techniques. The high lying levels are assigned to all expected autoionizing series. Moreover, some levels are observed. The theoretical interpretation is achieved by a combination of the nearly ab initio eigenchannel R-matrix and multichannel quantum-defect (MQDT) methods as well as by an empirical determination of the MQDT parameters in
the phase-shifted formulation. Theoretical energy level positions and excitation profiles are compared with the experimental
data confirming the identification of the observed structures. Strong mixing between series is found, while the ones do not couple with the series. Further insight into the strong channel mixing in the studied energy range is provided by a comprehensive review
of the excitation profiles in the vicinity of the 4p5p perturber as obtained from a number of intermediate levels used in the present and in earlier experiments. Systematic electron
correlation trends for series of , and are discussed.
Received: 20 November 1997 / Accepted: 15 January 1998 相似文献
8.
P. Müller B.A. Bushaw W. Nörtershäuser K. Wendt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):33-44
Isotope shifts and hyperfine structure have been measured in 4snp 1 P1 and Rydberg states for all stable calcium isotopes and the radioisotope 41Ca using high-resolution laser spectroscopy. Triple-resonance excitation via
Rydberg state was followed by photoionization with a CO2 laser and mass selective ion detection. Isotope shifts for the even-mass isotopes have been analyzed to derive specific mass
shift and field shift factors. The apparent isotope shifts for 41Ca and 43Ca exhibit anomalous values that are n-dependent. This is interpreted in terms of hyperfine-induced fine-structure mixing, which becomes very pronounced when singlet-triplet
fine-structure splitting is comparable to the hyperfine interaction energy. Measurements of fine-structure splittings for
the predominant isotope 40Ca have been used as input parameters for theoretical calculation of the perturbed hyperfine structure. Results obtained by
diagonalizing the second-order hyperfine interaction matrices agree very well with experimentally observed spectra. These
measurements allow the evaluation of highly selective and sensitive methods for the detection of the rare 41Ca isotope.
Received 17 December 1999 and Received in final form 29 March 2000 相似文献
9.
A. N. Grum-Grzhimaĭlo E. V. Gryzlova A. I. Magunov S. I. Strakhova 《Optics and Spectroscopy》2006,100(4):517-524
The effect of a laser field on the cross section of photoionization of an atom by probe radiation in the region of closely lying autoionizing resonances is studied theoretically. The cross sections in the region of the overlapping autoionizing Rydberg states 5p 5(2 P 1/2)6d′ J = 1 and 5p 5(2 P 1/2)8s′ J = 1 resonantly coupled with the discrete state 5p 5(2 P 3/2)7p[1/2]1 in the xenon atom are calculated. The behavior of the shape and position of resonances in relation to the frequency and intensity of laser radiation is studied. 相似文献
10.
Relativistic multichannel treatment of autoionization Rydberg series of 4s^2nf(n=4- 23)J^π -(7/2)° for scandium
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Based on relativistic multichannel theory, this paper calculates the energy levels of autoionization Rydberg series 4s^2nf(n=4- 23)J^π -(7/2)° of scandium at different levels of approximation within the framework of multichannel quantum defect theory. The present results show that the dipole polarizations play an important role. Considering the dynamical dipole polarization effects, this paper finds that the difference between calculated and experimental quantum defects for the 4s^2nf(n=4- 23)J^π -(7/2)° series is generally about 0.01- 0.03. Furthermore, the reason that 4s^216f is obscured in experimental spectra is suggested to be the interaction with the neighbouring resonance state converged to 3d^2(^1G4) of Sc^+. 相似文献
11.
Using the configuration interaction Pauli-Fock including core polarization (CIPFCP)
approach we have calculated absolute total and partial cross sections for photoionization
of excited
mp
5(m + 1)p J = 0−3
levels in Ar, Kr and Xe (m = 3−5) near threshold. Particular emphasis is
paid to the lineshapes of the odd mp
1/25
n(s/d)′
autoionizing
resonances and their variation with the character of the intermediate excited
J = 0−3 state. For selected intermediate levels of Ar and Kr the
computed cross sections are compared with laser spectroscopic measurements; good agreement
between the theoretical and experimental lineshapes and branching ratios for different
resonances is observed. 相似文献
12.
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
13.
B. Pilawa I. Keilhauer G. Fischer S. Knorr J. Rahmer A. Grupp 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):321-330
The magnetic properties of the cyclic compound [Fe6(bicine)6] LiClO4
. 2MeOH are reported. The cluster Fe6(bicine)6 forms an antiferromagnetically coupled ring structure of Fe III ions. The magnetic susceptibility is measured between 2 and 300 K and yields the exchange coupling of J/k
B = - 27.5±0.5 K. The field dependence of the magnetic moment is studied at 3 and 6 K in magnetic fields up to 5 T. The zero-field
splitting of the first excited spin states with S = 2 and 3 are determined by ESR at 94 GHz. The intra-molecular interactions of the Fe III ions are analyzed and the on-site anisotropy of the Fe III due to the ligand-configuration is determined to d /k
B = - 0.633±0.008K.
Received 28 October 2002 / Received in final form 22 February 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: bernd@piobelix.physik.uni-karlsruhe.de 相似文献
14.
B. Viaris de Lesegno J.C. Karam M. Boustimi F. Perales C. Mainos J. Reinhardt J. Baudon V. Bocvarski D. Grancharova F. Pereira Dos Santos T. Durt H. Haberland J. Robert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):25-34
A new Stern Gerlach interferometer operating with a nozzle beam of metastable argon atoms Ar* (3p5 4s, 3
P
2) is described. The selection of incoming (polarisation) and outgoing (analysis) Zeeman sublevels is achieved by use of laser
induced transitions at two wavelengths, 811.5 nm (closed J = 2 → J = 3 transition) and 801.5 nm (open J = 2 → J = 2 transition). Linear superpositions of Zeeman sublevels, just beyond the polariser and just before the analyser, are prepared
by means of two zones where Majorana transitions take place. In between, a controlled magnetic field configuration (the phase
object) is produced within a triple μ-metal shielding. Standard interference patterns are obtained by scanning the field and
detecting the atoms by secondary electron emission from a Faraday cup. When a static radial magnetic gradient is used, the
beam profile is modulated by interference. The transverse pattern, which can be translated at will by adding a homogeneous
field, is observed for the first time using a multi-channel electron multiplier followed by a phosphor screen and a CCD camera.
The results satisfactorily agree with all theoretical predictions.
Received 27 June 2002 / Received in final form 20 September 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: perales@lpl.univ-paris13.fr
RID="b"
ID="b"UMR 7538 du CNRS 相似文献
15.
M. A. Kalyar S. Mahmood S.-U. Haq N. Amin M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):229-236
We report a systematic line shape analysis study of the 6p7p configuration
based 1P1, 3D1 and 3P1 autoionizing
resonances in barium using a Nd:YAG pumped dye laser system in conjunction
with a thermionic diode ion detector. The even parity isolated autoionizing
resonances have been approached via four intermediate states 6 snp
1P1 (6 ≤n ≤8) and 5d6p 1P1. A comparison of
the Fano parameters of the resonance profiles reveals that the width of an
autoionizing resonance is independent of the excitation path while the line
profile parameter changes with the selection of different intermediate
states. 相似文献
16.
The new experimental results on the effective quantum numbers and term energies of the highly excited odd-parity 4s4d 3D1,2,3 →4snf 3F2,3,4 Rydberg transitions of zinc have been presented. The experiment was performed using the three dye lasers simultaneously pumped by the second harmonic (532?nm) of the Q-switched Nd:YAG laser. The new observation includes the 4snf 3F3 (12?≤n?≤?50) series excited from the 4s4d 3D2 intermediate level. In addition, the 4snf 3F2 (12?≤n?≤?28) and 4snf3F4 (12?≤n?≤?33) series are observed from the thermally populated 4s4d 3D1,3 fine structure components. The ionization potential of zinc has been determined from the unperturbed 4snf 3F3 series as 75769.31?±?0.15?cm?1, which is in excellent agreement with the previously reported value. 相似文献
17.
M. Grether M. Fortes M. de Llano J.L. del Rıo F.J. Sevilla M.A. Solıs A.A. Valladares 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):117-124
We solve the problem of a Bose or Fermi gas in d-dimensions trapped by δ ⩽ d mutually perpendicular harmonic oscillator potentials. From the grand potential we derive their thermodynamic functions (internal
energy, specific heat, etc.) as well as a generalized density of states. The Bose gas exhibits Bose-Einstein condensation
at a nonzero critical temperature T
c if and only if d + δ > 2, along with a jump in the specific heat at T
c if and only if d + δ > 4. Specific heats for both gas types precisely coincide as functions of temperature when d + δ = 2. The trapped system behaves like an ideal free quantum gas in d + δ dimensions. For δ = 0 we recover all known thermodynamic properties of ideal quantum gases in d dimensions, while in 3D for δ = 1, 2 and 3 one simulates behavior reminiscent of quantum wells, wires anddots, respectively. Good agreement is found between experimental critical temperatures for the trapped boson gases 37
87Rb, 3
7Li, 37
85Rb, 2
4He, 19
41K and the known theoretical expression which is a special case for d = δ = 3, but only moderate agreement for 11
27Na and 1
1H.
Received 17 July 2002 / Received in final form 14 October 2002 Published online 21 January 2003
RID="a"
ID="a"e-mail: mdgg@hp.fciencias.unam.mx 相似文献
18.
M. A. Baig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):437-442
We report new high resolution photoabsorption measurements of the
5d-subshell excitation spectra of mercury using a 3-meter normal incidence
spectrograph equipped with a 6000 line/mm holographic grating and
synchrotron radiation emitted by the Bonn 2.5 GeV electron accelerator as
the background source of continuum. The observed spectra reveal autoionizing
resonances attached to the 5d9(2D5/2)6s2 and
5d9(2D3/2)6s2 parent ion levels of mercury. We have
analysed the line shapes of the lower members of the 5d96s2 np and
nf J = 1 autoionizing resonances using the phase shifted formulation of the
MQDT and extracted the interaction parameters. 相似文献
19.
S. Westermann T. Amthor A. L. de Oliveira J. Deiglmayr M. Reetz-Lamour M. Weidemüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):37-43
We investigate excitation transfer and migration
processes in a cold gas of rubidium Rydberg atoms.
Density-dependent measurements of the resonant population exchange
for atoms initially excited into the 32P3/2(|mJ|=3/2) state
are compared with a Monte Carlo model for coherent energy
transfer. The model is based on simulations of small atom
subensembles involving up to ten atoms interacting via coherent
pair processes. The role of interatomic mechanical forces due to the
resonant dipole-dipole interaction is investigated.
Good agreement is found between the experimental data and the
predictions of the model, from which we infer that atomic motion
has negligible influence on the energy transfer up to Rydberg
densities of 108 cm-3, that the system has to be described in terms
of many-body dynamics, and that the energy transfer
preserves coherence on microsecond timescales. 相似文献
20.
E. V. Gryzlova A. N. Grum-Grzhimailo A. I. Magunov S. I. Strakhova 《Optics and Spectroscopy》2010,109(1):59-65
Optical activity of xenon atoms in the vacuum UV range induced by circularly polarized laser light is studied theoretically.
The optical activity arises in the vicinity of the autoionizing state 5p
5(2
P
1/2)8s′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
as a result of its coupling via the laser field with the discrete state 5p
5(2
P
3/2)7p
$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
. Polarization variations of the vacuum UV radiation upon its propagation through the atomic medium are calculated, and the
possibility of controlling this polarization is discussed. Manifestations of nonresonant coupling of the discrete state with
the broad autoionizing state 5p
5(2
P
1/2)6d′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
induced by the overlap of the Rydberg autoionizing series in xenon are studied. 相似文献