共查询到20条相似文献,搜索用时 31 毫秒
1.
V. Wippel C. Binder W. Huber L. Windholz M. Allegrini F. Fuso E. Arimondo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):285-291
A two element magneto-optical trap (MOT) for Na and 7Li or 6Li is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first 2P3/2 excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise
to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out
of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions.
Received 21 March 2001 and Received in final form 3 August 2001 相似文献
2.
P. Cren C.F. Roos A. Aclan J. Dalibard D. Guéry-Odelin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(1):107-116
We demonstrate experimentally the continuous and pulsed loading of a slow and cold atomic beam into a magnetic guide. The
slow beam is produced using a vapor loaded laser trap, which ensures two-dimensional magneto-optical trapping, as well as
cooling by a moving molasses along the third direction. It provides a continuous flux larger than 109 atoms/s with an adjustable mean velocity ranging from 0.3 to 3 m/s, and with longitudinal and transverse temperatures smaller
than 100 μK. Up to 3×108 atoms/s are injected into the magnetic guide and subsequently guided over a distance of 40 cm.
Received 19 February 2002 Published online 28 June 2002 相似文献
3.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
4.
F. Pereira Dos Santos F. Perales J. Léonard A. Sinatra Junmin Wang F. Saverio Pavone E. Rasel C.S. Unnikrishnan M. Leduc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):15-22
We present experimental results on the two-body loss rates in a magneto-optical trap of metastable helium atoms. Absolute
rates are measured in a systematic way for several laser detunings ranging from -5 to -30 MHz and at different intensities,
by monitoring the decay of the trap fluorescence. The dependence of the two-body loss rate coefficient β on the excited state
( 23
P
2) and metastable state ( 23
S
1) populations is also investigated. From these results we infer a rather uniform rate constant K
sp = (1±0.4)×10-7 cm3/s.
Received 8 September 2000 and Received in final form 19 December 2000 相似文献
5.
M. Lontano D. Ryutov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):347-351
We demonstrate the in situ detection of cold 87Rb atoms near a dielectric surface using the absorption of a weak, resonant evanescent wave. We have used this technique in
time of flight experiments determining the density of atoms falling on the surface. A quantitative understanding of the measured
curve was obtained using a detailed calculation of the evanescent intensity distribution. We have also used it to detect atoms
trapped near the surface in a standing-wave optical dipole potential. This trap was loaded by inelastic bouncing on a strong,
repulsive evanescent potential. We estimate that we trap 1.5×104 atoms at a density 100 times higher than the falling atoms.
Received 14 May 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: spreeuw@science.uva.nl 相似文献
6.
A continuous cold atomic beam from a magneto-optical trap 总被引:3,自引:0,他引:3
L. Cacciapuoti A. Castrillo M. de Angelis G.M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):245-249
We have developed and characterized a new method to produce a continuous beam of cold atoms from a standard vapour-cell magneto-optical
trap (MOT). The experimental apparatus is very simple. Using a single laser beam it is possible to hollow out in the source
MOT a direction of unbalanced radiation pressure along which cold atoms can be accelerated out of the trap. The transverse
cooling process that takes place during the extraction reduces the beam divergence. The atomic beam is used to load a magneto-optical
trap operating in an ultra-high vacuum environment. At a vapour pressure of 10-8mbar in the loading cell, we have produced a continuous flux of 7×107atoms/s at the recapture cell with a mean velocity of 14 m/s. A comparison of this method with a pulsed transfer scheme is
presented.
Received 19 February 2001 相似文献
7.
F.X. Gadéa T. Leininger A.S. Dickinson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):251-255
An improved ab initio calculation has been performed for the potential for the LiH a 3Σ+ state, using two very large basis sets. The Basis Set Superposition Error (BSSE) correction has been determined for both
basis sets and the non-Born-Oppenheimer correction estimated to be negligible. The best potential is approximately 10% deeper
than the previous estimate. Vibrational energies and scattering lengths have been calculated for 6,7LiH(D) with both potentials, with and without the BSSE correction, and also with an estimated potential expected to bracket
the true potential. The 7LiH scattering length is estimated to be (45 ± 4)a0 and hence the low-energy cross-section in the best a 3Σ+ potential is about half that calculated previously. Enhanced cooling by 7Li of trapped H atoms remains feasible.
Received 30 April 2001 相似文献
8.
F. Pereira Dos Santos J. Léonard Junmin Wang C. J. Barrelet F. Perales E. Rasel C. S. Unnikrishnan M. Leduc C. Cohen-Tannoudji 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):103-109
We recently observed a Bose-Einstein condensate in a dilute gas of 4He in the 23S1 metastable state. In this article, we describe the successive experimental steps which led to the Bose-Einstein transition
at 4.7 μK: loading of a large number of atoms in a MOT, efficient transfer into a magnetic Ioffé-Pritchard trap, and optimization
of the evaporative cooling ramp. Quantitative measurements are also given for the rates of elastic and inelastic collisions,
both above and below the transition.
Received 15 October 2001 相似文献
9.
L.G. Marcassa R.A.S. Zanon S. Dutta J. Weiner O. Dulieu V.S. Bagnato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):317-321
Using a technique that consists in ionizing atoms out of the 5P
1/2
fragments originated in the cold collision process, we have measured the contribution of the fine structure changing collision
(FS) to the total trap loss rate of cold 85Rb. Our results show that FS contribution is responsible for about 4% of the total trap loss. This result should stimulate
new theoretical discussions involving exoergic cold collisions.
Received 26 October 1998 and Received in final form 2 February 1999 相似文献
10.
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
11.
R. Jung S. Gerlach R. Schumann G. von Oppen U. Eichmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):415-419
We report on the first successful loading of a magneto-optical trap (MOT) with metastable He atoms from a Stark-slower. Thereby,
deceleration of the atoms relies on laser-atom interaction in an inhomogeneous electric field. We show that the results obtained
are comparable with early results from other groups achieved with a Zeeman slower. The Stark slower, which is able to fully
control the final velocity of the atomic He beam, is the first step in achieving complete spin independent kinematic control
based solely on electric fields.
Received 2 October 2002 / Received in final form 20 January 2003 Published online 29 April 2003
RID="a"
ID="a"e-mail: eichmann@mbi-berlin.de 相似文献
12.
Ch. Lisdat O. Dulieu H. Knöckel E. Tiemann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):319-328
We present a new determination of the potential curves and interactions of the coupled electronic states A
1
Σ
+
u
and b
3
Π
u
of the potassium dimer, based on new laser spectroscopy measurements within a molecular beam, combined with data available
in the literature. We used a new global deperturbation approach, involving the Fourier Grid Hamiltonian method for energy
level calculation. A standard deviation of 1.2 is obtained corresponding to a variance of 7.5×10
-3
cm-1, representing a significant improvement compared to the standard deviation of 4 yielded by the traditional local deperturbation
approach.
Received 12 June 2001 and Received in final form 3 September 2001 相似文献
13.
An atom faucet 总被引:3,自引:0,他引:3
W. Wohlleben F. Chevy K. Madison J. Dalibard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):237-244
We present a simple and efficient source of slow atoms. From a background vapour loaded magneto-optical trap (MOT), a thin
laser beam extracts a continuous jet of cold rubidium atoms. The jet that is typical to leaking MOT systems is created without
any optical parts placed inside the vacuum chamber. We also present a simple three dimensional numerical simulation of the
atomic motion in the presence of these multiple saturating laser fields combined with the inhomogeneous magnetic field of
the MOT. At a pressure of P
Rb87 = 10-8 mbar and with a moderate laser power of 10 mW per beam, we generate a flux Φ = 1.3×108 atoms/s with a mean velocity of 14 m/s and a divergence of 10 mrad.
Received 13 January 2001 相似文献
14.
F.-R. Carminati M. Schiavoni Y. Todorov F. Renzoni G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):311-317
We describe the pump-probe spectroscopy of atoms cooled in a 3D lin⊥lin optical lattice. Our pump-probe configuration consists of two laser fields detuned with respect to the lattice fields.
This scheme allows to clearly identify in the probe transmission spectrum the Brillouin and Raman resonances, by studying
their positions as functions of the angle between the pump and probe beams. We describe these resonances in detail, and compare
the experimental results to the theoretical predictions. Our conclusions are supported by transport-spectroscopy measurements,
which allow to distinguish between contributions to the light scattering from propagating and non-propagating atoms.
Received 8 April 2002 / Received in final form 9 September 2002 Published online 12 November 2002 相似文献
15.
J. Dabrowski J. Rożynek G.S. Anagnostatos 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):125-131
It is shown that among four models of the Nijmegen baryon-baryon interaction only model F --which leads to a repulsive potential
felt by the Σ hyperon inside the nucleus-- is consistent both with the analysis of Σ- atoms and of the (K
-,π) reactions. The Nijmegen models are used to determine the strong complex single-particle (s.p.) potential of Σ-, and to calculate the strong-interaction shifts and widths of the lowest observed levels of Σ- atoms. The results obtained with model F are in best agreement with the experimental data.
Received: 15 January 2002 / Accepted: 14 March 2002 相似文献
16.
U. Schlöder H. Engler U. Schünemann R. Grimm M. Weidemüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(3):331-340
We investigate collisional properties of lithium and cesium which are simultaneously confined in a combined magneto-optical
trap. Trap-loss collisions between the two species are comprehensively studied. Different inelastic collision channels are
identified, and inter-species rate coefficients as well as cross-sections are determined. It is found that loss rates are
independent of the optical excitation of Li, as a consequence of the repulsive Li*-Cs interaction. Li and Cs loss by inelastic inter-species collisions can completely be attributed to processes involving
optically excited cesium (fine-structure changing collisions and radiative escape). By lowering the trap depth for Li, an
additional loss channel of Li is observed which results from ground-state Li-Cs collisions changing the hyperfine state of
cesium.
Received 28 December 1998 and Received in final form 16 February 1999 相似文献
17.
18.
A. Fioretti C. Amiot C.M. Dion O. Dulieu M. Mazzoni G. Smirne C. Gabbanini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):189-198
We report the detailed analysis of translationally cold rubidium molecule formation through photoassociation. Cold molecules
are formed after spontaneous decay of photoexcited molecules from a laser cooled atomic sample, and are detected by selective
mass spectroscopy after two-photon ionization into Rb
2
+
ions. A spectroscopic study of the 0
g
-
(5
S
+ 5
P
3/2
) pure long-range state of 87Rb2 is performed by detecting the ion yield as a function of the photoassociation laser frequency; the spectral data are theoretically
analyzed within the semiclassical RKR approach. Molecular ionization is resonantly enhanced through either the 2
3
Π
g
or the 2
3
Σ
+
g
intermediate molecular states. Some vibrational levels of the latter electronic state are observed and assigned here for
the first time. Finally, cold molecules formation rates are calculated and compared to the experimentally measured ones, and
the vibrational distribution of the formed molecules in the a
3
Σ
+
u
ground triplet state is discussed.
Received 18 January 2001 and Received in final form 10 April 2001 相似文献
19.
G. Modugno G. Roati M. Inguscio M.S. Santos G.D. Telles L.G. Marcassa V.S. Bagnato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):409-413
We report a comparative investigation of trap loss rates in a magneto-optical trap for two potassium isotopes, 39K and 40K, as a function of trap light intensity. The isotopes present a quite similar behavior for the loss rates at high intensities,
and a sudden increase of the loss rates at low intensities is present in both cases. While for 39K such increase can be explained assuming that the major contribution to the losses comes from hyperfine changing collisions,
a different loss mechanism must be considered for 40K, which has an inverted ground state hyperfine structure. The experimental results of both isotopes are well reproduced by
an alternative model based on radiative escape as the dominant loss mechanism.
Received 1st May 2002 / Received in final form 19 October 2002 Published online 4 March 2003
RID="a"
ID="a"Alternative address: Dipartimento di Fisica, Universitá di Trento, 38050 Povo (Tn), Italy.
RID="b"
ID="b"e-mail: marcassa@if.sc.usp.br 相似文献
20.
K. Maniadaki L.A.A. Nikolopoulos P. Lambropoulos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):205-209
We present detailed calculations for one- and two-photon above-threshold detachment (ATD) cross-sections of the negative positronium
ion Ps
-
(
e
+
e
-
e
-
), below the threshold of Ps(n
= 2), using a configuration interaction (CI) method on a B splines basis. Both the one- and two-photon detachment cross-sections
have a form similar to the corresponding spectra of the H- ion, scaled accordingly. The peak value of the one-photon cross-section agrees very well with the calculations by Bathia
and Drachman [1], while it differs from those by Igarashi et al. [2], which give a value of 15% lower. Two-photon detachment cross-sections are also reported.
Received 24 January 2002 / Received in final form 9 April 2002 Published online 19 July 2002 相似文献