共查询到20条相似文献,搜索用时 468 毫秒
1.
A. Brioude F. Lequevre J. Mugnier C. Bovier J. Dumas J.C. Plenet 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(1):115-119
Very thin ZrO
2
films (few nanometers) have been prepared by sol-gel process. These films were deposited onto a stack of a thin silver layer
evaporated on a glass substrate for Surface Plasmons Resonance (SPR) experiments. The first aim of this work is to study the
high densification of the sol-gel films followed by the refractive index and thickness accurate measurements at each step
of the annealing procedure, using an optical set-up based on SPR. Secondly, SPR excitation coupled with micro-Raman experiment
has also been performed to determine the thin films structure depending on layer thickness. Finally, Conventional Transmission
Electron Microscopy (CTEM) and High Resolution (HRTEM) studies have been conducted to check and complete Raman spectroscopy
results. A discussion compares the optical results and the Transmission Electron Microscopy observations and shows that ultra
thin layers structure is strongly depends on films thickness.
Received 14 May 2001 and Received in final form 2 January 2002 相似文献
2.
O.K. Moune Y. Rabinovitch D. Tétard M. Pham-Thi E. Lallier M.D. Faucher 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):275-291
This paper presents an investigation of Pr3+ doped in the D2 site of Y3Al5O12 (YAG), for the first time on a translucent ceramic sample free of spurious phases, impurity or pair sites. The optical study
is carried out by optical absorption, excitation, and emission by selective excitation into 1D2 and 3P0, at different temperatures between 20 K and 60 K, in the 4 300-23 000 cm-1 range. A detailed account of the line assignments is given. 67 over 91 levels of the 4f2 configuration are determined. Several crystal field calculations within the ground configuration 4f2 and the larger matrix 4f2+4f6p are carried out. The energy level fit is slightly improved by configuration interaction. The 3P2 and 1I6 levels are strongly mixed together by the large 6th order crystal field parameters. In sintered samples with different Pr3+ concentrations, satellite lines with intensities increasing quadratically with the concentration are observed. A few weak
lines forbidden in D2 site symmetry are observed.
Received 9 November 2001 and Received in final form 8 February 2002 相似文献
3.
A.V. Papoyan M. Auzinsh K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):63-71
We report results of a theoretical and experimental study of the ground state nonlinear Hanle effect under strong laser excitation.
It is shown that besides the well-known zero-magnetic field suppression of absorption on F
g = F→F
e = F - 1 transitions caused by population trapping, an optical pumping induced enhanced absorption occurs on F
g = F→F
e = F + 1 transitions for small B-fields. The latter effect becomes more pronounced for high F values. The experiment with atomic vapor of Cs (D2 line, F
g = 4) confirms an increase of the spectrally unresolved fluorescence yield at zero magnetic field and 600 mW/cm2 laser intensity by 9% or 42%, when excitation occurs with linearly or circularly polarized light, respectively. The results
of the experiment agree with numerical simulation studies using equations of motion for a density matrix.
Received 24 November 2001 / Received in final form 25 March 2002 Published online 24 September 2002 相似文献
4.
Vicari L 《The European physical journal. E, Soft matter》2002,9(4):335-340
We present a new pump probe laser beams configuration for the nonlinear optical characterization of microemulsions. We detect
the variation of the on-axis optical intensity of the probe beam as generated by the concentration profile induced in an optically
thin film of microemulsion by the pump beam. A mathematical model has been introduced to describe the phenomenon. The technique
allows the determination of both Kerr-like optical nonlinearity and time constants and, therefore, it gives information both
on cluster dimension and their shape. We discuss its application to WAD (water/AOT/decane, where AOT denotes sodium-bis-di-ethyl-sulfosuccinate)
with the application of a strong electric field of optical source. Comparison between theoretical predictions and experimental
results confirms the presence of giant optical nonlinearity in the absence of turbidity divergence. Chainlike shape of clusters,
of the kind already reported with the application of strong electric field, could justify this result.
Received 26 October 2002
RID="a"
ID="a"e-mail: vicari@na.infn.it 相似文献
5.
C. Fusco A. Fasolino T. Janssen 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(1):95-102
We study the dynamics of a dimer moving on a periodic one-dimensional substrate as a function of the initial kinetic energy
at zero temperature. The aim is to describe, in a simplified picture, the microscopic dynamics of diatomic molecules on periodic
surfaces, which is of importance for thin film formation and crystal growth. We find a complex behaviour, characterized by
a variety of dynamical regimes, namely oscillatory, “quasi-diffusive” (chaotic) and drift motion. Parametrically resonant
excitations of internal vibrations can be induced both by oscillatory and drift motion of the centre of mass. For weakly bound
dimers a chaotic regime is found for a whole range of velocities between two non-chaotic phases at low and high kinetic energy.
The chaotic features have been monitored by studying the Lyapunov exponents and the power spectra. Moreover, for a short-range
interaction, the dimer can dissociate due to the parametric excitation of the internal motion.
Received 8 July 2002 / Received in final form 15 November 2002 Published online 27 January 2003
RID="a"
ID="a"e-mail: fusco@sci.kun.nl. 相似文献
6.
H. Portales L. Saviot E. Duval M. Gaudry E. Cottancin J. Lermé M. Pellarin M. Broyer B. Prével M. Treilleux 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):197-200
Low-frequency Raman scattering experiments have been performed on thin films consisting of pure gold or gold-silver alloy
clusters embedded in alumina matrix. It is clearly shown that the quadrupolar vibrational modes are observed by Raman scattering
because of the effect of resonance with the excitation of the electronic surface dipolar plasmon. This is due to the strong
coupling between the collective electronic dipolar excitation and the quadrupolar vibrational modes. This effect of resonance
does not exist with the core electron excitations. The mixing of the conduction electron dipolar excitation (surface plasmon)
with the core electrons leads to the quenching of the resonant Raman scattering.
Received 16 November 2000 相似文献
7.
T. Meier P. Thomas S.W. Koch 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(2):249-256
Linear and nonlinear optical absorption spectra are studied theoretically for semiconductor nanorings penetrated by a magnetic
field. Due to the Aharanov-Bohm effect the spectral position as well as the oscillator strength of the exciton change periodically
as function of the magnetic flux enclosed by the ring. In the nonlinear differential absorption spectra it is found that the
magnetic field strongly modifies Coulomb many-body correlations. In particular, the magnetic-field-induced increase of the
exciton binding energy is accompanied by a decrease of the biexciton binding energy. The persistence of these effects in the
presence of energetic disorder is analyzed.
Received 31 January 2001 相似文献
8.
P.-G. Reinhard E. Suraud 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):315-322
We use time-dependent density functional theory coupled to molecular dynamics for ionic motion to compute the spectra of ionic
vibrations in small Na clusters. Comparison with results from the distance dependent tight-binding approach shows good agreement
between these two very different methods. We discuss the evolution of the spectra with cluster size and charge and the impact
of ionic vibrations on the optical response.
Received 23 July 2001 / Received in final form 5 July 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: suraud@irsamc.ups-tlse.fr 相似文献
9.
S.V. Dordevic D.N. Basov R.C. Dynes B. Ruzicka V. Vescoli L. Degiorgi H. Berger R. Gaál L. Forró E. Bucher 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(1):15-23
We present a comprehensive analysis of the optical constants of the two-dimensional dichalcogenide materials 2
H
-
TaSe
2
and 2
H
-
NbSe
2
, in an attempt to address the physics of two-dimensional correlated systems. The title compounds were studied over several
decades in frequency, from the far-infrared to the ultraviolet. Measurements with linearly polarized light have allowed us
to obtain both the in-plane and out-of-plane components of the conductivity tensor. Although the electromagnetic response
of dichalcogenides is strongly anisotropic, both the in-plane and out-of-plane components of the conductivity tensor share
many common features, including the presence of a well-defined metallic component, as well as a “mid-infrared band”. We discuss
the implications of these results in the context of the spectroscopic results of other classes of low-dimensional conductors
such as the high-temperature superconducting cuprates. In particular, the analysis of the redistribution of the spectral weight
as a function of temperature, as well as the behavior of the quasiparticles relaxation rate, points to significant distinctions
between the charge dynamics of dichalcogenides and other classes of low dimensional conductors.
Received 28 October 2002 / Received in final form 10 March 2003 Published online 23 May 2003
RID="a"
ID="a"e-mail: degiorgi@solid.phys.ethz.ch 相似文献
10.
M. Schnürer S. Ter-Avetisyan H. Stiel U. Vogt W. Radloff M. Kalashnikov W. Sandner P.V. Nickles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):331-335
Using 50 fs ( ∼ 2×1018 W/cm2) and 2 ps ( ∼ 5×1016 W/cm2) pulses from a Ti:Sa multi-TW laser at 800 nm wavelength large Xe-clusters ( 105...106 atoms per cluster) have been excited. Absolute yield measurements of EUV-emission in a wavelength range between 10 nm and
15 nm in combination with cluster target variation were carried out. The ps-laser pulse has resulted in about 30% enhanced
and spatially more uniform EUV-emission compared to fs-laser excitation. Circularly polarized laser light instead of linear
polarization results in enhanced emission which is probably caused by electrons gaining higher energies by the polarization
dependent optical field ionization process. An absolute emission efficiency at 13.4 nm of up to 0.8% in 2π sr and 2.2% bandwidth
has been obtained.
Received 11 January 2001 and Received in final form 27 March 2001 相似文献
11.
C. Voisin D. Christofilos N. Del Fatti F. Vallée 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):139-144
Femtosecond excitation and relaxation of nonequilibrium electrons are investigated in silver clusters using a two color pump-probe
technique with resonant excitation of the surface plasmon resonance and off resonant probing. The excitation process is shown
to be identical to that in metal films, and permits creation of a strongly athermal single electron excitation in a time scale
shorter than the duration of the pulses (25-30 fs), in agreement with the free-electron absorption model. Following the time
evolution of the nonequilibrium distribution yields information on the internal energy redistribution dynamics of the conduction
electrons and of its modification by confinement in metal clusters.
Received 1st December 2000 相似文献
12.
T. Mančal V. May 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(2):173-184
The optimal control (OC) scheme for molecular dynamics is applied to the study of ultrafast bridge mediated electron transfer
(ET). Utilizing the methods of dissipative quantum dynamics in combination with the OC approach the guided charge motion in
a donor-bridge-acceptor system including a single active vibrational coordinate is studied. The control field drives the optical
transition from the electronic ground-state of the ET system into the donor-level and can be used to prepare special electronic
and vibrational states. In particular, it is demonstrated that charge localization becomes possible at the acceptor or bridge
molecule as well as in the electronic ground-state of the ET system.
Received 30 August 2000 and Received in final form 25 October 2000 相似文献
13.
Ch. Nacke H. Stolz G. Manzke K. Henneberger 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):303-312
The influence of thermalized non-coherent carriers on the dielectric function of GaAs/AlAs quantum wells is investigated by
reflection spectroscopy. Experiments are performed using the method of spectral interferometry, where both amplitude and phase
of reflected pulses can be determined. For low excitation density the complex coefficient of reflection can be described using
as dielectric function a broadened Elliot formula. With increasing carrier density pronounced nonlinearities appear in both
amplitude and phase due to many-body effects between excited carriers. The nonlinear behavior fits very well to the results
of a many-body theory based on the Semiconductor Bloch equations including memory effects in the scattering processes between
carriers and the polarization induced by the probe pulse.
Received 29 May 2002 / Received in final form 23 September 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: manzke@physik3.uni-rostock.de 相似文献
14.
The hopping motion of a classical bounded pair of two particles along a chain is investigated. It is shown that in the asymmetric
case of the system dynamics including excited states which differ from the respective ground states by the barrier to be overcome
by one of the two particles, the over- and underpopulation of these excited states leads to a directed motion of the particle
pair. Thereby, overpopulation results in one direction of motion, whereas underpopulation results in the opposite direction,
and the mean velocity is determined by the amount of over-resp. underpopulation. For small deviations from equilibrium, the
system exhibits linear response well known from other ratchet-type models. Possible generalizations and applications are discussed.
Received 17 August 2001 and Received in final form 11 October 2001 相似文献
15.
L. Sanchez-Palencia P. Horak G. Grynberg 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):353-364
We numerically study the spatial diffusion of an atomic cloud experiencing Sisyphus cooling in a three-dimensional linlin optical lattice in a broad range of lattice parameters. In particular, we investigate the dependence on the size of the
lattice sites which changes with the angle between the laser beams. We show that the steady-state temperature is largely independent
of the lattice angle, but that the spatial diffusion changes significantly. It is shown that the numerical results fulfill
the Einstein relations of Brownian motion in the jumping regime as well as in the oscillating regime. We finally derive an
effective Brownian motion model from first principles which gives good agreement with the simulations.
Received 8 August 2001 and Received in final form 6 November 2001 相似文献
16.
P. Monachesi R. Capelli R. Del Sole 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(2):159-166
We calculate the optical functions of Pd using the ab initio, all-electron Full Potential Linear Muffin Tin Orbital method within the framework of the Density Functional Theory in the
Local Density approximation. We test, in the case of Pd, the convergence of the dielectric function and energy loss function
in different energy ranges vs. the completeness of the basis and give a quantitative estimate of the accuracy. The present approach opens the possibility
of extending the energy range where the optical functions can be calculated with good accuracy without increasing the computational
effort.
Received 4 September 2001 相似文献
17.
J. Tempere J.T. Devreese 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(1):27-33
A sum rule for the first frequency moment of the optical absorption of a many-polaron system is derived, taking into account
many-body effects in the system of constituent charge carriers of the many-polaron system. In our expression for the sum rule,
the electron-phonon coupling and the many-body effects in the electron (or hole) system formally decouple, so that the many-body
effects can be treated to the desired level of approximation by the choice of the dynamical structure factor of the electron
(hole) gas. We calculate correction factors to take into account both low and high experimental cutoff frequencies.
Received 26 April 2000 and Received in final form 5 December 2000 相似文献
18.
P. Farmanara H.-H. Ritze V. Stert W. Radloff I.V. Hertel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(2):193-209
Neutral ammonia clusters (NH3)m are photo-excited to the electronic state by a deep UV femtosecond laser pump pulse. Within a few hundred femtoseconds a significant fraction of the clusters
rearrange to form an H-transfer state (NH3)m-2NH4(3s)NH2 with the subunit NH4 in its 3s electronic ground state. This state is then electronically excited by a time-delayed infrared control pulse of variable wavelength.
Finally, a third (probe) pulse in the UV ionizes the clusters for detection. The lifetime of the excited (NH3)m-2NH4(3p)NH2 states is found to vary between 2.7 and 0.13 ps depending on cluster size and excitation energy. It increases drastically
upon deuteration. The corresponding cluster size-dependent photoelectron spectra allow us to disentangle the underlying energetics
of the excitation and ionization process and reveal additional processes, such as nonresonant ionization or dissociative ionization.
The experimental findings suggest that the excited H-transfer ammonia complexes with m > 2 are deactivated by an internal conversion process back to the electronically lowest H-transfer state followed by fast
dissociation.
Received 22 September 2001 and Received in final form 31 January 2002 相似文献
19.
S. Residori N. Olivi-Tran 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):255-259
In 2D optical patterns obtained in a Liquid Crystal Light Valve with optical feedback, we show a new kind of geometrical frustration
which comes from the imposed form of the boundaries. The circular section of the incoming laser beam presents a symmetry which
belongs to the O(2) group, whereas the optical feedback selects patterns with a symmetry restrained to a dihedral subgroup
of O(2). By imposing boundaries which respect the symmetry of the dihedral group, we lift the frustration and obtain perfectly
ordered patterns.
Received 19 January 2001 and Received in final form 2 June 2001 相似文献
20.
J. Bellessa V. Voliotis T. Guillet D. Roditchev R. Grousson X.L. Wang M. Ogura 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):499-505
We report on time-resolved microphotoluminescence experiments in a single GaAs/GaAlAs V-shaped quantum wire as a function
of optical excitation intensity. At low pump power we observe that excitons are localized in quantum boxes formed by the local
potential minima existing along the wire axis. As the pump power is increased, state filling of the lowest lying levels of
the boxes appears. When two carriers occupy the first excited level of the box, a very efficient Auger scattering occurs,
leading to a transfer of carriers from one box to another neighbouring one. The intradot Auger scattering time has been measured
and is of the same order of magnitude as the LA-phonon emission rate.
Received 5 February 2001 相似文献