共查询到20条相似文献,搜索用时 7 毫秒
1.
M. Morato J. O. Caceres A. Gonzalez Ureña 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):215-218
Deflection of a cold supersonic NO beam seeded in He has been observed when
these molecules interact with both static and a resonant oscillating electric field. The NO beam splits into two beams each
one deflecting about 0.5° towards the positive and negative direction of the Stark field when the employed resonant frequency
between the two Stark levels of the NO molecule is 1515 kHz. This deflection angle is about four orders of magnitude higher
than the value one would expect from the NO dipole moment and the employed RF field gradient. This phenomenon suggests the
possibility of a significant translational motion perpendicular to the beam axis, which is induced by the resonant RF electric
field on the cold and high-density supersonic beam. 相似文献
2.
M. Morato J. O. Caceres A. González Ureña 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(2):199-208
Deflection of a cold supersonic toluene beam seeded in He has been observed
when these molecules interact with both a static and a resonant oscillating
electric field. The toluene beam splits into two beams each one peaking at a
deflection angle of 1 degree towards the positive and negative direction of
the Stark field when the employed resonant frequency between the two Stark
levels of the toluene molecule is 1411 kHz. This deflection angle is about
four orders of magnitude higher than the value one would expect from the
toluene dipole moment and the employed RF field gradient. Different
hypothesis are suggested to explain the observed strong beam splitting
including the possibility of transverse beam interferences induced by both
the resonant RF field and the transverse uniform electric field. A
theoretical model is presented based on molecular beam interferences induced
by the resonant RF field which seems to account satisfactorily for the
present observations. 相似文献
3.
B. Friedrich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):209-214
We present a simple analytic approximation for evaluating the
ensemble-averaged orientation or alignment of a beam of molecules subjected
to a strong static or radiative field. This approximation is based on the
eigenproperties which polar or polarizable molecules exhibit in the
strong-field, harmonic-librator limit, and on the Boltzmann statistics of
the free rotor states which adiabatically correlate with the harmonic
librator states. For either the permanent or induced dipole case, the
resultant formula involves just two dimensionless parameters which
characterize the strength of the molecule-field interaction and the
rotational temperature. The net polarization of a molecular beam thus
obtained is shown to be in an excellent agreement with the exact values
computed numerically from first principles. The validity range of the
approximation includes the large-interaction, high temperature regions of
the parameter space where first-principle calculations are onerous. 相似文献
4.
E. Vliegen P. A. Limacher F. Merkt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):73-80
The full three-dimensional velocity distributions of decelerated and accelerated particles in a Stark decelerator for Rydberg
atoms and molecules have been
measured. In the experiment, argon atoms in a supersonic beam are excited to low-field and high-field seeking Stark states
with principal quantum number in the range n=15 to 25 and are decelerated in a 3 mm long decelerator consisting of four electrodes
on which time-dependent voltages are
applied. The time dependence of the resulting inhomogeneous electric field is chosen such that the decelerating force acting
on the high-field seeking states is maximized
at each point along the trajectories. The three-dimensional velocity distribution of the atoms before and after the deceleration
is determined by measuring
times of flight and two-dimensional images of the atomic cloud on the detector.
Under optimal deceleration conditions, the decrease in kinetic energy in the longitudinal dimension amounts to 1.0×10-21 J and the increase in mean kinetic
energy in the transverse dimensions is only 1.0×10-23 J. The corresponding temperatures of 100 mK and 300 mK in the two transverse dimensions are sufficiently
low that trapping can be envisaged. The possibility of focusing a Rydberg atom beam is demonstrated experimentally. 相似文献
5.
G. Stern B. Battelier R. Geiger G. Varoquaux A. Villing F. Moron O. Carraz N. Zahzam Y. Bidel W. Chaibi F. Pereira Dos Santos A. Bresson A. Landragin P. Bouyer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):353-357
We describe the operation of a light pulse interferometer using cold 87Rb atoms in reduced gravity. Using a series of two Raman transitions induced by light pulses, we have obtained Ramsey fringes
in the low gravity environment achieved during parabolic flights. With our compact apparatus, we have operated in a regime
which is not accessible on ground. In the much lower gravity environment and lower vibration level of a satellite, our cold
atom interferometer could measure accelerations with a sensitivity orders of magnitude better than the best ground based accelerometers
and close to proven spaced-based ones. 相似文献
6.
Y. Kimura Y. Kitahama K. Takazawa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):203-208
Experimental set-up for studying effects of a strong magnetic field on a structure and a decay dynamics of molecules, was
designed and constructed. A vacuum chamber, in which a molecular beam propagated, was mounted in a bore of a superconducting
magnet. Laser light crossed the molecular beam in the magnetic field and excited the molecules. Fragment or parent ions produced
through sequential decay processes, were extracted by an electric field parallel to the magnetic field and detected by a microchannel
plate. By measuring the time-of-flight from the photo-excitation to the ion-detection, a species of ions —mass and charge
state— was identified. A performance of the set-up was demonstrated using the resonance enhanced multiphoton ionization process
through the
X2Π-A2Σ+ transition of nitric oxide (NO) molecules. A mass resolution m/Δm ≥180±6 was obtained in the field up to 10 T. This was
the first successful result demonstrating the sufficient mass resolution obtained by the time-of-flight technique in the strong
magnetic field up to 10 T. Parent NO+ ions were selectively detected by the mass spectrometer and the ion current was measured as a function of the frequency of
the laser light. Rotational transition lines were measured with a sufficient S/N ratio in the field up to 10 T. 相似文献
7.
Z. Y. Wang Z. Zhang Q. Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):127-131
In this paper, we proposed new constructions of atom interferometers manipulated through the toroidal trap formed by the interference
patterns of two co-propagation Laguerre-Gaussian (LG) beams. The coherent splitting and merging of the atomic ensemble, which
is essential for the atom interferometer, is realized by the interference pattern of two LG beams. Along the beam propagation
direction, a single-well trap is evolved into a double-well trap and then recombined back into a single-well trap, which can
be used to form an atom interferometer. 相似文献
8.
B. C. Sawyer B. K. Stuhl B. L. Lev J. Ye E. R. Hudson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):197-209
The transverse motion inside a Stark decelerator plays a large role in the total efficiency of deceleration. We differentiate
between two separate regimes of molecule loss during the slowing process. The first mechanism involves distributed loss due
to coupling of transverse and longitudinal motion, while the second is a result of the rapid decrease of the molecular velocity
within the final few stages. In this work, we describe these effects and present means for overcoming them. Solutions based
on modified switching time sequences with the existing decelerator geometry lead to a large gain of stable molecules in the
intermediate velocity regime, but fail to address the loss at very low final velocities. We propose a new decelerator design,
the quadrupole-guiding decelerator, which eliminates distributed loss due to transverse/longitudinal couplings throughout
the slowing process and also exhibits gain over normal deceleration to the lowest velocities. 相似文献
9.
S. D. Hogan J.-P. Connerade 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):47-50
We discuss the effects of experimental resolution on
the analysis of nearest neighbour energy level spacings for the
signatures of underlying classically chaotic electron dynamics.
Through a numerical treatment we arrive at a new dimensionless
resolution criterion which must be met in order that statistical
studies of this kind be considered meaningful. 相似文献
10.
T. Müller M. Gilowski M. Zaiser P. Berg Ch. Schubert T. Wendrich W. Ertmer E. M. Rasel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(3):273-281
We present a compact and transportable inertial sensor for
precision sensing of rotations and accelerations. The sensor consists
of a dual atom interferometer operated with laser-cooled 87Rb.
Raman processes are employed to coherently manipulate the matter
waves. We describe and characterize the experimental apparatus. A
method for passing from a compact geometry to an extended
interferometer with three independent atom-light interaction zones is
proposed and investigated. The extended geometry will enhance the
sensitivity by more than two orders of magnitude which is necessary
to achieve sensitivities better than 10-8rad/s/. 相似文献
11.
C. Baumgarten B. Braun M. Capiluppi G. Ciullo P. F. Dalpiaz H. Kolster P. Lenisa H. Marukyan A. Nass D. Reggiani M. Stancari E. Steffens 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):343-350
The spin-exchange collision cross-section for hydrogen atoms has been
measured for the first time in the low temperature range 40–100 K by
using the polarized hydrogen gas target of the HERMES experiment at DESY
(Hamburg, Germany). The results agree with a previous measurement in the
overlapping temperature region 80–100 K, while seem to hint an
increasing behaviour with temperature in the region 50–80 K. 相似文献
12.
B. Zmerli N. Ben Nessib M. S. Dimitrijević 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):389-395
We investigated here temperature dependence of Stark
widths for neutral atom spectral lines in order to find a more
precise method for scaling with temperature than sometimes used
dependence T-1/2, which is often inadequate particularly for
Stark broadening of neutral emitter lines. We found here an
analytical scaling with temperature within simplified
semiclassical approaches of Freudenstein and Cooper and
Dimitrijević and Konjević. For analysis of the temperature
dependence, lines of HeI were used. 相似文献
13.
C. V. Nielsen J. K. Lyngsø A. Thorseth M. Galouzis K. T. Therkildsen E. D. van Ooijen J. W. Thomsen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):111-119
This paper demonstrates a detailed experimental study of our cloverleaf
magnetic trap for sodium atoms. By using polarization dependent
Zeeman spectroscopy of our atomic beam, passing the magnetic trap
region, we have determined important trap parameters such as
gradients, their curvatures and corresponding trap frequencies. Experimental findings
are compared to theoretical calculations as well as complementary
methods of characterizing the trap. 相似文献
14.
A. Miffre M. Jacquey M. Büchner G. Trénec J. Vigué 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):353-365
Using an atom interferometer, we have measured the static electric
polarizability of 7Li α=(24.33 ±0.16)×10-30
m3 = 164.2±1.1 atomic units with a 0.66% uncertainty. Our experiment, which is similar to an experiment done on sodium in 1995
by Pritchard and co-workers, consists in
applying an electric field on one of the two interfering beams and measuring the resulting phase-shift. With respect to Pritchard's
experiment, we have made several improvements which
are described in detail in this paper: the capacitor design is such that the electric field can be calculated analytically;
the phase sensitivity of our interferometer is substantially better,
near 16 mrad/
; finally our interferometer is species selective so that impurities present in our atomic beam (other alkali atoms or lithium
dimers) do not perturb our
measurement. The extreme sensitivity of atom interferometry is well illustrated by our experiment: our measurement amounts
to measuring a slight increase Δv of the atom velocity v
when it enters the electric field region and our present sensitivity is sufficient to detect a variation Δv/v ≈6 ×10-13. 相似文献
15.
Stefano De Leo Pietro Rotelli 《The European Physical Journal C - Particles and Fields》2009,62(4):793-797
We develop the potential scattering of a spinor within the context of perturbation field theory. As an application, we reproduce,
up to second order in the potential, the diffusion results for a potential barrier of quantum mechanics. An immediate consequence
is a simple generalization to arbitrary potential forms, a feature not possible in quantum mechanics. 相似文献
16.
X. Baillard M. Fouché R. Le Targat P. G. Westergaard A. Lecallier F. Chapelet M. Abgrall G. D. Rovera P. Laurent P. Rosenbusch S. Bize G. Santarelli A. Clairon P. Lemonde G. Grosche B. Lipphardt H. Schnatz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):11-17
We present a new evaluation of an 87Sr optical lattice clock using spin polarized atoms. The frequency of the
1S0→3P0 clock transition is found to be 429 228 004 229 873.6 Hz with a fractional uncertainty of
2.6×10-15, a value that is comparable to the frequency difference between the various primary standards throughout the
world. This measurement is in excellent agreement with a previous one of similar accuracy [Phys. Rev. Lett. 98, 083002 (2007)]. 相似文献
17.
We discuss a strongly entangled two-particle state of motion that emerges naturally from the double-pulse dissociation of
a diatomic molecule. This state, which may be called dissociation-time entangled, permits the unambiguous demonstration of
nonclassical correlations by violating a Bell inequality based on switched single-particle interferometry and only position
measurements. We apply time-dependent scattering theory to determine the detrimental effect of dispersion. The proposed setup
brings into reach the possibility of establishing nonclassical correlations with respect to system properties that are truly
macroscopically distinct. 相似文献
18.
Stefan Gmuca 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(4):387-392
The results of the modern relativistic Dirac-Brueckner calculations of nuclear matter are parametrized in terms of the relativistic- mean-field theory with scalar and vector nonlinear selfinteractions. It is shown that the inclusion of the isoscalar vector-meson quartic selfinteraction is essential for obtaining a proper density dependence of the vector potential in the mean-field model. The obtained mean-field parameters represent a simple parametrization of effective interaction in nuclear matter. This interaction may be used in the mean-field studies of the structure of finite nuclei without the introduction of additional free parameters.This work was supported in part by the Grant Agency of the Slovak Academy of Sciences under Grant No. GA SAV-517/1991. 相似文献
19.
C. Mennerat-Robilliard L. Guidoni K.I. Petsas P. Verkerk J.-Y. Courtois G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):33-45
All the bright optical lattices studied so far have been designed to obtain a circularly polarized light at the bottom of
the optical potential wells. This condition minimizes the departure rate of the atoms from the fundamental adiabatic surface
and permits an oscillating regime in a large range of parameters. We present here an experimental study of cesium atoms in
a three-dimensional optical lattice, where the light is linearly polarized at the bottom of the potential wells. Temperature
measurements and pump-probe spectroscopy give similar results for this lattice and for the conventional lin lin lattice (which have circular polarizations at the bottom of the wells) despite the fact that one lattice operates in
the jumping regime and the other in the oscillating regime. We study the behaviour of the two types of lattices in a longitudinal
magnetic field, with particular emphasis on the zero field and strong field regimes. The strong field situation is very simple
because the eigenstates are then almost pure Zeeman substates and the adiabatic and diabatic potential surfaces are identical.
The comparison between the zero-field and the high-field situations shows that the diabatic potentials are more appropriate
to account for experimental observations in the novel lattice.
Received: 9 October 1997 / Accepted: 6 November 1997 相似文献
20.
J. Kobayashi Y. Izumi K. Enomoto M. Kumakura Y. Takahashi 《Applied physics. B, Lasers and optics》2009,95(1):37-42
We have performed two-photon photoassociation experiments in atomic Bose–Einstein condensate (BEC) of 87Rb with spin degree of freedom which is created by all-optical method with CO2 lasers. The spinor character of the molecules has been revealed by the photoassociation spectrum with a new structure. The
hyperfine structure of the molecules near the dissociation limit is identified by observations of the Zeeman and AC-Stark
effects of the molecules. The molecules have been spin-selectively probed by the use of the light shift. This result would
open the new possibility of research on novel spinor molecular BEC. 相似文献