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1.
V. A. Kartoshkin 《Optics and Spectroscopy》2010,109(5):674-679
Complex cross sections of the spin exchange are calculated for the first time for interacting Na and K atoms based on the
data on the singlet (X
1Σ+) and triplet (a
3Σ+) potentials that describe the interaction of these alkali-metal atoms in the ground state. The obtained cross sections allow
one to theoretically consider the polarization transfer processes and calculate the relaxation times and the magnetic resonance
frequency shifts caused by Na-K spin-exchange collisions. 相似文献
2.
V. A. Kartoshkin 《Optics and Spectroscopy》2011,111(6):881-884
Singlet (X
1Σ+) and triplet (a
3Σ+) potentials of interaction of two potassium atoms residing in the ground state (4s
2
S
1/2) are presented. Based on the given interaction potentials, the complex cross sections of spin exchange q = [`(q)] + i[`([`(q)])]q = \bar q + i\overline{\overline q} for the system under investigation are calculated. Obtained dependences of the real and imaginary parts of the spin-exchange
cross section on temperature allow one to obtain information both on the broadening of a magnetic resonance line of K atoms
and on the frequency shift of the magnetic resonance during collision. 相似文献
3.
V. A. Kartoshkin 《Optics and Spectroscopy》2014,116(4):548-551
Based on data on the singlet (X 1Σ+) and triplet (a 3Σ+) potentials describing the interaction of two Na atoms in the ground state, the complex cross sections of spin exchange for the system under investigation are calculated. The obtained cross sections allow one to determine relaxation times, as well as magnetic-resonance frequency shifts caused by spin-exchange Na-Na collisions. 相似文献
4.
A. Pashov P. Popov H. Knöckel E. Tiemann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):241-249
We report on high resolution Fourier-transform spectroscopy of fluorescence to the a3Σu
+ state induced by two-photon or two-step excitation from the X1Σg
+ state to the 23Πg state in the molecule K2. These spectroscopic data are combined with recent results of Feshbach resonances and two-color photoassociation spectra
for deriving the potential curves of X1Σg
+ and a3Σu
+ up to the asymptote. The precise relative position of the triplet levels with respect to the singlet levels was achieved
by including the excitation energies from the X1Σg
+ state to the 23Πg state and the frequencies of the fluorescence down to the a3Σu
+ state in the simultaneous fit of both potentials. The derived precise potential curves allow for reliable modeling of cold
collisions of pairs of potassium atoms in their 2S ground state.
Electronic supplementary material Supplementary Online Material 相似文献
5.
H. Ouerdane M. J. Jamieson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(1):27-32
Using improved experimentally based X1Σ+ and a3Σ+ molecular potentials of NaRb, we apply the variable phase method to compute new data for low energy scattering of 23Na atoms by 85Rb atoms and 87Rb atoms. These are the scattering lengths and volumes, numbers of bound states and effective ranges, which we use to obtain
the low energy spin-change cross section as functions of the system temperature and the isotope masses. From an analysis of
the contributions of s-wave and p-wave scatterings to the elastic cross section we estimate temperatures below which only
s-wave scattering is dominant. We compare our quantal results to data obtained from the semiclassical approximation. We supply
evidence for the existence of a near zero energy p-wave bound state supported by the singlet molecular potential. 相似文献
6.
D. Oblak J. Appel P. J. Windpassinger U. B. Hoff N. Kjærgaard E. S. Polzik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):67-73
We present a simultaneous analysis of the X1
Σ
+ and the a3
Σ
+ electronic ground states of the NaK molecule. Excitation of the [B 1
Π, c3
Σ
+]-system made it possible to record fluorescence to rovibrational levels of both ground states simultaneously with a Fourier-transform
spectrometer. For the first time high lying levels in the triplet state with v = 17 and v = 18 were seen, the highest possible v = 19 for 23Na-39K was not observed. The joint evaluation of the retrieved data leads to accurate potential energy curves, that describe the
experimental data within their experimental uncertainty of 0.005 cm−1. Cold collision properties like scattering length and Feshbach resonance positions are calculated with these potentials and
compared to other predictions. 相似文献
7.
The true potential energy curves forX
1
Σ
+, a3
π
r,A
1
π,e
3
Σ
−,E
1
Σ
+,c
3
π
i states of astrophysically important molecule SiO, whose spectra were observed in the sunspots, have been constructed using
the method of Lakshman and Rao. Dissociation energy and ionization potential have been estimated as 65,350 cm−1 and 92,854 cm−1 respectively and found to be in good agreement with the values cited in literature.
The true potential energy curves forX
1
Σ
+,D
1
π andE
1
Σ
+ states of SiS molecule have been constructed by the same method and its dissociation energy in the ground state has been
estimated using Hulburt-Hirschfelder potential function as 54,765 cm−1 in good agreement with 53,250.9 cm−1 given by Herzberg. 相似文献
8.
The known and new heterogeneous spectral data on the triplet states a
3Σ
u
+
, 23Πg, 23Σ
g
+
, 33Πg, and 43Σ
g
+
of the K2 dimer are simultaneously fitted. The data published in J. Mol. Spectrosc. 234, 41 (2005) are refined. The new information used in the analysis contains the data on the 23Σ
g
+
state, which have not been considered previously. The range of internuclear distances where the potential function of the
lowest triplet state a
3Σ
u
+
is defined is extended.
Original Russian Text ? V.B. Sovkov, V.S. Ivanov, D. Li, F. Xie, Li Li, 2007, published in Optika i Spektroskopiya, 2007,
Vol. 103, No. 5, pp. 747–751. 相似文献
9.
We use the spin non-degenerate single impurity Anderson model to investigate the influence of the local spin polarization
to the Kondo effect. By using the Schrieffer-Wolff transformation, we obtain a generalized s-d exchange Hamiltonian, which
describes the interaction between a polarized local spin and conduction electrons. In this case, the singlet is no longer
an eigenstate as shown by variational calculations where the splitting of the local energy Δ = ɛ
d↑ − ɛ
d↓ can be arbitrarily small. The local spin polarization generates the instability of the singlet ground state of the S = 1/2 s-d exchange model.
相似文献
10.
Using the technique of helicity amplitudes, the electromagnetic process e
+
e
− → μ+μ− is theoretically investigated in the one-photon approximation. The structure of the triplet states of the final (μ+μ−) system is analyzed. It is shown that in the case of unpolarized electron and positron the final muons are also unpolarized,
but their spins are strongly correlated. Explicit expressions for the components of the correlation tensor of the final (μ+μ−) system are derived. The formula for the angular correlation at the decays of final muons μ+ and μ−, produced in the process e
+
e
− → μ+μ−, is obtained. It is demonstrated that spin correlations of muons in the process of electron-positron pair annihilation have
the purely quantum character, since one of the incoherence inequalities for the correlation tensor components is always violated.
The additional contribution of the weak interaction of lepton neutral currents through the virtual Z
0 boson is considered; it is established that, taking into account the weak interaction, the qualitative character of the muon
spin correlations does not change. 相似文献
11.
Using the technique of helicity amplitudes, the electromagnetic process e
+
e
− → μ+μ− is theoretically investigated in the one-photon approximation. The structure of the triplet states of the final (μ+μ−) system is analyzed. It is shown that in the case of unpolarized electron and positron the finalmuons are also unpolarized,
but their spins are strongly correlated. Explicit expressions for the components of the correlation tensor of the final (μ+μ−) system are derived. The formula for the angular correlation at the decays of final muons μ+ and μ−, produced in the process e
+
e
− → μ+μ−, is obtained. It is demonstrated that spin correlations of muons in the process of electron-positron pair annihilation have
the purely quantum character, since one of the incoherence inequalities for the correlation-tensor components is always violated.
The additional contribution of the weak interaction of lepton neutral currents through the virtual Z
0 boson is considered; it is established that, taking into account the weak interaction, the qualitative character of the muon
spin correlations does not change.
The text was submitted by the authors in English. 相似文献
12.
Five red degraded bands belonging to theC
2
Σ
+ —X
2
Π system of NH+ were excited in a mild condensed discharge through flowing ammonia and were photographed on a 3.4 meter Ebert grating spectrograph
at a dispersion of 2.5 A/mm. The rotational analyses of these bands enabled us to evaluate the vibrational and rotational
constants accurately. The rotational energy levels of theΠ
+ andΠ
− levels of theν=0 and 1 levels of the ground state,X
2
Π, were fitted in James expression using two sets of rotational constants. The perturbations observed in theX
2
Π state caused by thea
4
Σ
− state were examined in greater detail. 相似文献
13.
The rate constant for spin exchange in a system consisting of a metastable helium atom and an alkali-metal atom is determined.
An experiment on optical orientation of atoms established that the rate constant for spin exchange in a collision of a metastable
23
S
1 helium atom with a cesium atom in the 62
S
1/2 ground state equals (2.8±0.8)×10−9 cm3 s−1. The rate constant for chemoionization of cesium atoms by metastable helium atoms was determined at the same time to be (1.0±0.3)×109 cm3s−1.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 3, 145–148 (10 August 1997) 相似文献
14.
The effective spin Hamiltonian for undoped cuprates is constructed in the framework of the realistic multiband p-d model with the parameters calculated from first principles. The exchange interaction parameter is defined as the sum of the
antiferromagnetic and ferromagnetic contributions, which are determined by the two-hole triplet terms. The ferromagnetic and
antiferromagnetic contributions of the excited terms compensate each other to a large extent. It is shown that the antiferromagnetic
contribution of the two-hole ground singlet 1
A
1g
to the exchange interaction is dominant.
Original Russian Text. V.A. Gavrichkov, S.G. Ovchinnikov, 2008, published in Fizika Tverdogo Tela, 2008, Vol. 50, No. 6, pp.
1037–1041. 相似文献
15.
K. Chakrabarti J. Tennyson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):31
The R-matrix method is used to study electron collisions with the BeH+
molecular ion. The diatomic version of the UK Molecular R-matrix codes is used and a
configuration-interaction calculation is first performed for the BeH+ target to
obtain its potential energy curves for 19 lowest singlet and triplet states. Scattering
calculations are then done to yield excitation and rotational excitation cross sections in
the energy range 0 − 14 eV. Additionally we also obtain bound states of BeH and their
quantum defects at the BeH equilibrium bond length 2.5369a
0.
Resonance positions and widths for Feshbach resonances in the e-BeH+ system are
also obtained and presented at the equilibrium bond length
2.5369a
0. 相似文献
16.
A. S. Kirillov 《Technical Physics》2011,56(12):1731-1736
The quenching rate constants for the singlet states (a′)(1)Σ
u
− (v = 1−17), a
(1)Π
g
(v = 0−14), and w
(1)Δ
u
(v = 0−13) of molecular nitrogen colliding with an N2 molecule are calculated using quantum-chemical approximations. It is shown for the first time that both the intramolecular
and intermolecular processes of electronic excitation transfer are significant for these states. Calculated rate constants
are in satisfactory agreement with experimental data. 相似文献
17.
P. Jasik J. Wilczyński J. E. Sienkiewicz 《The European physical journal. Special topics》2007,144(1):85-91
We report adiabatic potential energy curves of the
Li2
+ molecule. Our curves are tabulated according to
internuclear distance from 2 a0 to 100 a0. We
compare our theoretical results with the ones calculated by other
authors and potential energy curves derived from experiments. For
the ground state and 17 excited states we calculate spectroscopic
parameters and compare them with parameters obtained by other
authors. For the first time we present three new minima for
32Σu
+, 42Σu
+ and 22Πg
excited states. In our approach we use the configuration interaction
method where only the valence electrons of Li atoms are treated
explicitly. The core electrons are represented by pseudopotential.
All calculations are performed by means of MOLPRO program package. 相似文献
18.
I. Klincare M. Tamanis R. Ferber A. Zaitsevskii E. A. Pazyuk A. V. Stolyarov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):373-378
Radiative lifetimes for 2≤v′≤44 rovibronic C1Σ+ state levels of NaRb and quenching collision cross-sections with Rb atoms have been directly measured in a thermal cell by
detecting time resolved laser induced fluorescence after pulsed excitation. Many body multipartitioning theory was applied
to calculate C1Σ+-X1Σ+ and C1Σ+-A1Σ+ transition dipole moments. The relevant
ab initio matrix elements were converted to the C1Σ+ state radiative lifetimes. The strong spin-orbit A1Σ+∼ b3Π coupling effect on the total C → A transition probabilities and lifetimes of the C1Σ+ state is discussed. The measured radiative lifetimes show a decrease from 61 to 34 ns as the v′ values increase, the results being in good agreement with calculations. The averaged collisional quenching cross-section
value σ=(3±1)×10-14 cm2 was determined for NaRb (C1Σ+) + Rb collisions from the Stern-Volmer plots. 相似文献
19.
V. A. Pushkarchuk S. Ya. Kilin A. P. Nizovtsev V. E. Borisenko A. B. Filonov A. L. Pushkarchuk S. A. Kuten’ 《Optics and Spectroscopy》2010,108(2):247-253
The effect of the surface of diamond on atomic, electronic, and spin properties of diamond nanocrystals containing single
nitrogen-vacancy defects ([NV]− centers) is studied. The surface was modeled with clusters C33H30[NV]−, C66H72[NV]−, which were constructed based on bulk clusters C33H36[NV]− and C69H84[NV]−, respectively. In all cases, clusters in the triplet state S = 1 are considered with the cluster charge being −1. The geometric structure of clusters is optimized using the principle
of minimization of the total energy of the system; then, the electronic and spin characteristics of clusters are calculated
by the density functional theory. The isotropic and anisotropic hyperfine interaction constants of the electron spin of the
NV center with the nuclear spin of the nitrogen atom and 13C atoms located at different sites in the cluster are calculated. It is found that, in contrast to bulk clusters with [NV]-centers
in which the spin density is mainly localized at the three carbon atoms that are the nearest neighbors of the vacancy of the
center, upon arrangement of the NV center in the immediate proximity to the surface, the spin density is redistributed such
that it is mainly localized at the three carbon atoms that are the nearest neighbors of the nitrogen atom of the center and
at C atoms that form the first atomic layer of the (111) surface of the nanocrystal. 相似文献
20.
A. I. Reznikov S. Ya. Umanskii Yu. F. Chaikina 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(2):203-209
Rate constants for electron-vibrational energy exchange Ar(3
P
2) + N2(X
1Σ
g
+, ν = 0) → Ar(1
S
0) + N2(C
3Π
u
, ν′), where ν′ = 0, 1, 2, were calculated. Calculations were performed taking into account the presence of a resonance in electron scattering
by N2(X
1Σ
g
+). As a result, the interaction of Ar(3
P
2) with N2(X
1Σ
g
+, ν = 0) was characterized by attraction and, in the end, intersection of electron-vibrational potential surfaces correlating
with Ar(3
P
2) + N2(X
1Σ
g
+, ν = 0) and Ar(1
S
0) + N2(C
3Π
u
, ν′) at interparticle distances of 2.5–3.5 ?. Exchange interaction at which electron-vibrational transitions in the region of
intersection of electron-vibrational transitions in the region of intersection of electron-vibrational potential surfaces
accompanied by spin exchange were induced was calculated by the asymptotic method. The rate constants determined at 300–600
K were on the order of 10−11−10−12 cm3/s and weakly increased as the temperature grew. Mainly the C
3Π
u
, ν′ = 0 state of the N2 molecule was populated. The calculation results were in satisfactory agreement with the experimental data obtained at 300
K. 相似文献