共查询到19条相似文献,搜索用时 0 毫秒
1.
G. Grégoire M. Mons I. Dimicoli C. Dedonder-Lardeux C. Jouvet S. Martrenchard D. Solgadi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):227-231
The femtosecond photodissociation of CsI in the CsI-CH3CN complex has been studied. Recurrences are observed in the detection of the Cs+-CH3CN ion complex. They are assigned to the first vibrations of the Cs-NCCH3 bond formed after the CsI dissociation. This result is in good agreement with calculations on the similar NaI-CH3CN system which predict a linear structure for the ground state complex.
Received 27 October 1999 相似文献
2.
A.S. Shalabi M.M. Assem S. Abd El-Aal M.A. Kamel M.M. Abd El-Rahman 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(2):181-189
Ab initio calculations were performed for several suggested mechanisms of energy transfer between helium metastable particles and neon.
Optimized geometries and excited-state energies were calculated for neon excited-state complexes and the convergence properties
of the non-additive contributions to the interaction energies were examined. The most probable excitation-transfer mechanism
was found to be based on an energy difference of 0.0674 eV between the triplet excited state of and the singlet excited state of . No theoretical evidence was found for the production of neon singlet excited-state complexes other than 20.0858 to 20.4875
eV by the considered two-, three- and four-body models of energy transfer processes. The energy curves of the reactions involving
the excited-state complexes and are provided and compared with the previously reported experimental results on the reaction . The relation between the probability of energy transfer and laser activity is discussed. The non-additive contribution to
the total interaction energy of the nominated intermediate complex was found to be negligible, pointing to the possibility of constructing model potentials and simulation
of larger systems.
Received: 15 December 1998 / Received in final form: 20 March 1999 相似文献
3.
E. Czuchaj M. Kronicki J. Czub 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):345-353
Excitation spectra arising from A
3
0
+
←
X
1
0
+
and B
3
1 ←
X
1
0
+
electronic transitions in the Cd-rare gas (RG) van der Waals molecules are calculated using newly obtained theoretical potential
curves for these species. In the molecular structure calculations, Cd20+ and RG8+ cores are simulated by energy-consistent pseudopotentials which also account for scalar-relativistic effects and spin-orbit
(SO) interaction within the valence shell. Potential energies in the Λ
S coupling scheme have been obtained by means of ab initio complete-active-space multiconfiguration self consistent-field (CASSCF)/complete-active-space multireference second-order
perturbation theory (CASPT2) calculations with a total 28 correlated electrons, while the SO matrix has been computed in a
reduced CI space restricted to the CASSCF level. The final Ω potential curves are obtained by diagonalization of the modified SO matrix (its diagonal elements before diagonalization
substituted for the corresponding CASPT2 eigen-energies). The spectroscopic parameters for the ground and several excited
states of the Cd-RG complexes deduced from the calculated potential curves are in quite reasonable agreement with available
experimental data. In addition, the radial Schr?dinger equation for nuclear motion was solved numerically with the calculated
potentials to evaluate the corresponding vibrational levels and radial wavefunctions. The latter have been used in the calculation
of the appropriate Franck-Condon factors to yield information on relative intensities of the vibrational bands of the Cd-RG
complexes. The theoretical vibrational progressions are discussed in the context of experimental spectra.
Received 10 August 2000 and Received in final form 7 November 2000 相似文献
4.
D. Comparat C. Drag B. Laburthe Tolra A. Fioretti P. Pillet A. Crubellier O. Dulieu F. Masnou-Seeuws 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):59-71
We report on the formation of translationally cold Cs2 ground state molecules through photoassociation in the 1u attractive molecular state below the 6
s
1/2
+6
p
3/2
dissociation limit. The cold molecules are obtained after spontaneous decay of photoassociated molecules in a MOT and in
a dark SPOT. We also used polarized atoms, in the f
=3, m
f
=+3Zeeman ground state. Purely asymptotic and adiabatic calculations including hyperfine interaction and rotation are in excellent
agreement with observed structures. As expected, the 1u state is actually a pure long-range state, consisting of paired atoms, uniquely linked by the first terms of the multipole
expansion of the electrostatic interaction. A temperature of 20 K has been measured for the molecular cloud.
Received 19 July 1999 相似文献
5.
K. Orlovsky V. Grushevsky A. Ekers 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):133-146
We present results of theoretical studies of the non-resonant excitation transfer in Rb(7S) + Rb(5S) and Rb(5D) + Rb(5S) collisions
at thermal collision energies. Rb2 adiabatic molecular terms correlating with the 5S+7S, 5S+5D and 5P+5P states of separated atoms were calculated for internuclear
distances R > 20 a.u. using asymptotic approximation. Mechanisms of collisional population and quenching of the 5D state were treated
on the basis of the computed molecular terms, and the respective cross-sections were calculated. Theoretical cross-sections
are in good agreement with the experimental values at thermal collision energies ( K).
Received 13 November 1998 and Received in final form 22 November 1999 相似文献
6.
7.
M. Wernli E. Bodo F. A. Gianturco 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):267-272
The low-temperature (up to about 100 K) collisional
(de)excitation cross sections are computed using the full
coupled-channel (CC) quantum dynamics for both Li2 and Li2
+
molecular targets in collision with 4He. The interaction forces are
obtained from fairly accurate ab initio calculations and the
corresponding pseudo-rates are also computed. The results show
surprising similarities between sizes of inelastic flux distributions
within final states in both systems and the findings are connected
with the structural change in the molecular rotor features when the
neutral species is replaced by its ionic counterpart. 相似文献
8.
D. Baowan N. Thamwattana J. M. Hill 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):117-123
Carbon nanostructures are of considerable interest owing to their
unique mechanical and electronic properties. Experimentally, a wide
variety of different shapes are obtained, including both spherical
and spheroidal carbon onions. A spheroid is an ellipsoid with two
major axes equal and the term onion refers to a multi-layered
composite structure. Assuming structures of either concentric
spherical or ellipsoidal fullerenes comprising n layers, this
paper examines the interaction energy between adjacent shells for
both spherical and spheroidal carbon onions. The Lennard-Jones
potential together with the continuum approximation is employed to
determine the equilibrium spacing between two adjacent shells. We
also determine analytical formulae for the potential energy which
may be expressed either in terms of hypergeometric or Legendre
functions. We find that the equilibrium spacing between shells
decreases for shells further out from the inner core owing to the
decreasing curvature of the outer shells of a concentric structure. 相似文献
9.
G. Hermann B. Kaulakys G. Mahr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(2):129-137
Results of broadening and shift measurements of Doppler-free two-photon lines for transitions from the ground state to the
Rydberg states with intermediate principle quantum numbers of atomic thallium perturbed by rare gases are reported. The rates
show a distinct behaviour in this range of principle quantum numbers and significant dependence on the total angular momentum
of the upper nP state. The experimental results are compared with calculations using a Van der Waals potential and a superposition of polarization
and Fermi potentials. Additionally, broadening and shift rates of the transition Tl 6P
3/2
-9P
3/2
have been measured for quadrupolar as well as for mainly scalar excitation. The rates for both kinds of excitation coincide
within the limits of error reflecting the small perturbation of the 6P
3/2
state compared to that of the upper 9P
3/2
state.
Received: 6 August 1997 / Revised in final form: 29 November 1997 / Accepted: 11 December 1997 相似文献
10.
W. Helfrich 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):481-489
The problem of membrane softening by thermal undulations is revisited. In contrast to general belief, fluid membranes are
predicted to be stiffened, not softened, by their undulations. Equal values of the effective bending rigidity are calculated
from the interplay of local mean curvature modes (hats) on the basically flat membrane and from the coupling of spherical
harmonic modes with spherical curvature. In addition, a conjecture is made on the entropy of membrane closure. It relies on
a similarity of membrane closure to periodic boundary conditions.
Received: 10 June 1997 / Revised: 7 October 1997 / Accepted: 2 December 1997 相似文献
11.
A. V. Yakubovich I. A. Solov'yov A. V. Solov'yov W. Greiner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(1):23-34
We have investigated the potential energy surfaces for glycine
chains consisting of three and six amino acids. For these molecules
we have calculated potential energy surfaces as a function of the
Ramachandran angles ϕ and ψ, which are widely used for
the characterization of the polypeptide chains. These particular
degrees of freedom are essential for the characterization of
proteins folding process. Calculations have been carried out within
ab initio theoretical framework based on the density
functional theory and accounting for all the electrons in the
system. We have determined stable conformations and calculated the
energy barriers for transitions between them. Using a thermodynamic
approach, we have estimated the times of the characteristic
transitions between these conformations. The results of our
calculations have been compared with those obtained by other
theoretical methods and with the available experimental data
extracted from the Protein Data Base. This comparison demonstrates a
reasonable correspondence of the most prominent minima on the
calculated potential energy surfaces to the experimentally measured
angles ϕ and ψ for the glycine chains appearing in
native proteins. We have also investigated the influence of the
secondary structure of polypeptide chains on the formation of the
potential energy landscape. This analysis has been performed for the
sheet and the helix conformations of chains of six amino acids. 相似文献
12.
Effect of thermal undulations on the bending elasticity and spontaneous curvature of fluid membranes
We amplify previous arguments why mean curvature should be used as measure of integration in calculating the effective bending
rigidity of fluid membranes subjected to a weak background curvature. The stiffening of the membrane by its fluctuations,
recently derived for spherical shapes, is recovered for cylindrical curvature. Employing curvilinear coordinates, we then
discuss stiffening for arbitrary shapes, confirm that the elastic modulus of Gaussian curvature is not renormalized in the
presence of fluctuations, and show for the first time that any spontaneous curvature also remains unchanged.
Received 19 April 1999 and in Received in final form 7 January 2000 相似文献
13.
M. Sabidó J. de Andrés J. Sogas J. M. Lucas M. Albertí J. M. Bofill I. Rabadán A. Aguilar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(1):63-70
The dynamics of collisional processes between Mg atoms and caesium ions is studied using the hemiquantal (HQ) approach with
special attention to the collisional channels leading to Mg(3 1P) and Cs(6 2P) states, for which the corresponding emission excitation functions have been previously measured in our laboratory. The
radial and angular non-adiabatic couplings between the manifold of quasimolecular states have been determined using an ab
initio configuration interaction calculation. The cross-sections for the different channels, as a function of the laboratory
collisional energy, are compared with experimental values. The dynamical calculations indicate that, for the inelastic processes
considered, the range of relevant impact parameters is small, active collisions being of the head-on type.
. 相似文献
14.
A. Bielski D. Lisak R.S. Trawiński J. Szudy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):217-222
Using a laser-induced fluorescence method a detailed analysis of profiles of the 114Cd 326.1 nm line perturbed by N2 and CH4 was performed which revealed deviations from the ordinary Voigt profile. These deviations are shown to be consistent with
fits of experimental profiles to an asymmetric Voigt profile. Coefficients of the pressure broadening, shift and collision-time
asymmetry are determined and compared with those calculated for van der Waals interaction potential.
Received 29 November 2001 / Received in final form 12 July 2002 Published online 4 February 2003 相似文献
15.
Two direct methods to calculate fluctuation forces between rigid objects embedded in fluid membranes
The fluctuation-induced attractive interaction of rigid flat objects embedded in a fluid membrane is calculated for a pair
of parallel strips and a pair of equal circular disks. Assuming flat boundary conditions, we derive the interaction from the
entropy of the suppressed boundary angle fluctuation modes. Each mode entropy is computed in two ways: from the boundary angles
themselves and from the mean-curvature mode functions. A formula for the entropy loss of suppressing one or more mean-curvature
modes is developed and applied. For the pair of disks we recover the result of Goulian et al. and Golestanian et al. in a direct manner, avoiding any mappings by Hubbard-Stratonovitch transformations. The mode-by-mode agreement of the two
computed entropies in both systems confirms an earlier claim that mean curvature is the natural measure of integration for
fluid membranes.
Received 15 December 2000 相似文献
16.
J.P. Santos P. Patte F. Parente P. Indelicato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):27-31
Using a laser-induced fluorescence method a detailed analysis of profiles of the 114Cd 326.1 nm line perturbed by argon was performed which revealed deviations from the ordinary Voigt profile. These deviations
are shown to be consistent with fits of experimental profiles to an asymmetric Voigt profile. Coefficients of the pressure
broadening, shift and collision-time asymmetry are determined and compared with those calculated in the adiabatic approximation
for different interaction potentials.
Received 19 July 2000 相似文献
17.
F. Monroy F. Ortega R.G. Rubio 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):745-754
The thermoelastic behaviour of polyvinylacetate monolayers spread on an aqueous subphase has been studied using rheological
data previously published (Monroy et al., Phys. Rev. E 58, 7629 (1998)). The results show fluid-like viscoelastic behaviour well above a transition temperature , while at lower temperatures a soft solid-like behaviour emerges. The correlation between thermodynamic and elastic properties
below can be described in terms of scaling laws.
Received 12 January 1999 and Received in final form 11 June 1999 相似文献
18.
We present an experimental study of the adsorption of hydrophobic highly charged polyelectrolytes on a neutral and hydrophobic
surface, the air/water interface. The polymer was a randomly sulphonated polystyrene with charge fractions between 0.3 and
0.9 and the adsorbed layers were characterised by Langmuir through measurements, ellipsometry and X-ray reflectivity. The
adsorption rate is always very slow and the resulting layers are very thin (< 3 nm). A maximum of adsorption with the charge
fraction is observed which we relate to the conformation of the chains in solution. We show that adsorption is partially irreversible,
strongly hysteretic and that the state of an adsorbed layer depends on its history.
Received 16 June 2000 相似文献
19.
M. Yamazaki N. Kishimoto K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):47-57
Collisional ionization of styrene (phenylethylene), 2-vinylpyridine, and
4-vinylpyridine with metastable He*(23S) atoms were studied by means of
collision-energy/electron-energy resolved two-dimensional Penning
ionization electron spectroscopy. Collision energy dependence of partial
ionization cross-sections, which reflects the anisotropic interactions
between a He*(23S) atom and the target molecules, indicates that
attractive interaction for the out-of-plane access of a He*(23S) atom
to phenyl group is stronger than that for the out-of-plane access to vinyl
group. Moreover, it was found for vinylpyridines that the attractive
interaction around π electrons became weaker than that for styrene, and
that the attractive interaction for the in-plane access to the nitrogen atom
is stronger than that for out-of-plane π-directions. However, in
2-vinylpyridine, the hydrogen atom of vinyl group prevents a He*(23S)
atom from approaching to the nitrogen atom along in-plane directions, and
thus the attractive interactions around the nitrogen atom were shielded by
the vinyl group. The experimentally observed anisotropic interactions were
qualitatively supported with ab initio model interaction potential calculations
between a Li (He*(23S)) atom and the target molecule. Concerning with
electronic structures of investigated molecules, the assignment of Penning
ionization electron spectrum for 4-vinylpyridine was discussed on the basis
of different behavior of collision-energy dependence of partial ionization
cross-sections, and the satellite ionization band in Penning ionization
electron spectra was also reported for styrene. 相似文献