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1.
The quasi-line low-temperature (4.2 K) fluorescence excitation spectra of two porphyrins, meso-tetraazaporphin and meso-tetrapropylporphin introduced into an n-octane matrix are measured in the range of the S 0S 2 electronic transition. A characteristic feature of these spectra is that a conglomerate of quasi-lines—a structured complex band—is observed instead of one 0–0 quasi-line of the S 0S 2 transition. In this band, the intensity distributions for the two main types of impurity centers considerably differ from each other. The occurrence of such conglomerates is interpreted as a result of nonadiabatic electronic-vibrational interactions between vibronic S 2 and S 1 states (the complex vibronic analogue of the Fermi resonance). The frequencies and intensities of individual transitions determined from the deconvolution of complex conglomerates are used as the initial data for solving the inverse spectroscopic problem: the determination of the unperturbed electronic and vibrational levels of states involved in the resonance and the electronic-vibrational interaction matrix elements between them. This problem is solved with a method developed previously. The energy intervals between the S 2 and S 1 electronic levels of the two main types of impurity centers formed by molecules of a given porphyrin in the crystal matrix are found to significantly differ from each other (~100 cm?1). At the same time, the energies of the unperturbed vibrational states of the S 1 electronic level partcipating in the resonance are very close to each other for these two types of impurity centers.  相似文献   

2.
Miriam Lemanska 《Physica A》2008,387(12):2719-2735
A dynamical system of infinite volume and of infinite number of identical interacting particles occupying energy levels has been constructed as the limit of an infinite sequence of finite, equivalent systems of increasing size and particle number. Systems both in equilibrium and in non-equilibrium state (designated S=limSk, , respectively, k=1,2,…) were investigated. The main results are:(i) The values in the T-limit (thermodynamic limit) of the physical quantities characterizing these systems are determined.(ii) The time evolution process both in and in systems is governed by the non-linear rate equations with common initial conditions pi(t0), where pi(t)=ni(t)/N are the occupation probabilities at time t. The time evolution process in the and systems is the same. The asymptotic approach to the equilibrium state is proved.(iii) For the case of the equilibrium state, the Boltzmann probability distribution pi is given by the equation −lnpi+a+eib=0 common to Sk and S systems with the same value of a and b. The term a=β−1ae, where ae is the free energy per particle, and .(iv) The conditions for the equivalence of the systems being in equilibrium and also of the ones in non-equilibrium are stated.  相似文献   

3.
The fluorescence excitation spectra of jet-cooled carbazole molecules at vibrational temperatures of 55 and 80 K and the fluorescence spectrum of these molecules excited by radiation at the frequency of a pure electronic transition are measured. As the vibrational temperature increases, the excitation spectra exhibit a series of lines of the same symmetry, which are caused by the interaction of the active vibration with a subensemble of optically inactive vibrations. The final symmetry of the totally and nontotally symmetric vibrations is determined from the shape of the rotational contours of the lines of vibronic transitions. The values of a decrease in the frequency of the nontotally symmetric vibrations in the first excited electronic state S 1 due to their interaction with the electronic state S 2 are calculated to be up to 100 cm?1. The frequencies of the pure electronic transitions in the absorption and fluorescence spectra coincide with each other and are equal to 30809 cm?1, the frequencies of vibrations in the ground state S 0 exceeding the frequencies of the corresponding vibrations in the excited state S 1. The degree of polarization of the integral fluorescence is determined for a series of vibronic transitions of the a 1 and b 2 final symmetry that are observed in the fluorescence excitation spectra, and the contribution of the intensity with the borrowed polarization θ to the integral fluorescence is calculated. It is found that the intensity θ is higher for the transitions of the b 2 symmetry and can reach ≈50%.  相似文献   

4.
Laser induced fluorescence (LIF), single vibronic level dispersed fluorescence (DFL) spectra, and high resolution rotationally resolved scans of the S0–S1 transition of the C10H8 isomer 1-phenyl-1-butyn-3-ene have been recorded under jet-cooled conditions. The S0–S1 origin of PAV at 34 922 cm−1 is very weak. A vibronic band located 464.0 above the origin, assigned as 3010, dominates the LIF excitation spectrum, with intensity arising from vibronic coupling with the S2 state. High resolution scans of the S0–S1 origin and 3010 vibronic bands determine that the former is a 65:35 a:b hybrid band, while 3010 is a pure a-type band, confirming the role for vibronic coupling and identifying the coupled state as the S2 state. DFL spectra of all vibronic bands in the first 800 cm−1 of the spectrum were recorded. A near-complete assignment of the vibronic structure in both S0 and S1 states is obtained. Herzberg–Teller vibronic coupling is carried by two vibrations, ν28 and ν30, involving in-plane deformations of the vinylacetylene side chain, leading to Duschinsky mixing evident in the intensities of transitions in excitation and DFL spectra. Extensive Duschinsky mixing is also present among the lowest five out-of-plane vibrational modes, involving motion of the side chain. Comparison with the results of DFT B3LYP and TDDFT calculations with a 6-311+G(d,p) basis set confirm and strengthen the assignments.  相似文献   

5.
A general method of constructing canonical decompositions of Yang-Mills fields is presented. The gauge dependence is concentrated to a minimal set of variables which parametrize the group space of the gauge group. The decompositions fall into different classes for different boundary conditions and are characterized by a specific connection to gauge-fixing conditions which are consistent with these boundary conditions. All classes connected to gauge-fixing conditions on the field strength Eai yield local decompositions generalizing a similar decomposition given by Goldstone and Jackiw for SU(2) Yang-Mills. All classes connected to gauge-fixing conditions. which also involve Aai yield non-local decompositions in space. Explicit canonical decompositions are given for those classes which are connected to the Coulomb and axial gauges as well as the gauges of the form BabkEbk = 0, where Babk are constants.  相似文献   

6.
A solvable Ising-system withnn-interactions as a basic system is considered. This system is assumed to undergo a phase transition so that the thermal quantityq i> 0 2 /N, which is not necessarily the order parameter of the basic system, is different from zero (q≠0) forT c. The whole system consists of the basis {S i} and an equal number of additional spins η i which are coupled linearly with the basic spinsS i through an exchange constantJ i which is distributed at random. The pairs of spinsS i i can be interpreted as clusters with an internal degree of freedom. The specific heat Δc and the susceptibility Δχ of the internal degree of freedom can be separated exactly and show typical spin glass properties: the specific heat Δc is an analytic function over the whole temperature range and the susceptibility Δχ shows a cusp at the transition temperatureT c of the basic system.  相似文献   

7.
A quantum logic is defined as a setL of functions from the set of all statesS into [0, 1] satisfying the orthogonality postulate: for any sequencea 1,a 2, ... of members ofL satisfyinga i+a j≤1 forij there isbL such thatb+a 1+a 2+...=1. Every logicL is in a natural way an orthomodular σ-orthocomplemented partially ordered set (L, ≤, ′) with members ofS inducing a full set of measures onL. It is shown that a logicL is quite full if and only if (L,≤,′) is isomorphic to an orthocomplemented set lattice of subsets ofS. Sufficient conditions are given in order that a quite full logic be representable in the set of projection quadratic formsf(u)=(Pu, u) on a complex Hilbert space, or in the set of trace functionsf(A)=Trace (AP) generated by projectionsP, where the domain off is the set of non-negative self-adjoint trace operators of trace 1 in a complex Hilbert space.  相似文献   

8.
Low-lying energy states of the [Fe3S4]0 cluster have been calculated by taking into account the double exchange, superexchange and vibronic interaction. It was found that the adiabatic potential of the excited state withS=0 corresponds to the full delocalization of the “excess” charge. From the analysis of experimental data of Mössbauer spectroscopy and the temperature dependence of the magnetic susceptibility the double exchange parametert≥4000 cm?1 and the vibronic interaction parameter λ2/2k cm?1 have been estimated.  相似文献   

9.
张承福 《物理学报》1980,29(6):778-787
本文指出,对于Sy≡ky2ρi2≥1的短波模,通常所用的漂移波本征方程是不自洽的,由此而得出“普适模是稳定的”结论也是不恰当的。我们在弱剪切条件(Ls/rn>>[2Timi/Tme]1/2)下导出了适合Sy≥1的方程,并讨论了其近似表式。在最低级近似下(主要是忽略k′ρi2项),证明了不存在γ≥0的不稳定模式。考虑一级修正项后,尚不能得出确定的结论。 关键词:  相似文献   

10.
Abnormally low frequencies observed for the out-of-plane vibration (b1) of the A?1A2 electronic state of formaldehyde (H2CO) and for the analogous carbonyl hydrogen vibration (a″) of A?1A″ propynal (HCCCHO) are modeled by means of two-state calculations of vibronic coupling with higher singlet states, 1B2 and 1A′, respectively. In each case, the active vibration is the out-of-plane hydrogen motion. The same vibronic calculations reproduce also the large positive anharmonicities of the active vibrations in the A?1, n) states; for H2CO the calculated vibrational spacing alternates as observed, consistent with the known nonplanar structure, while in propynal the calculated spacing increases regularly, thus predicting an effectively planar structure. The nonplanarity of H2CO is caused mainly by a vibronic coupling constant nearly twice that of propynal. The H2CO coupling constant is near the value estimated independently by means of the intensity “borrowed” by the S1-S0 transition from the much stronger S2-S0 transition. Brief consideration is given to analogous vibrational levels of the 1A2 state of H2CS and of the 3A2 state of D2CO in the vibronic context of this paper.  相似文献   

11.
We observed fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation of jet-cooled perylene-h 12 and perylene-d 12, and carefully examined the vibrational structures of the S0 1 A g and S1 1 B 2u states. We performed vibronic assignments on the basis of the results of ab initio calculation, and found that the vibrational energies in the S1 state are very similar to those in the S0 state, indicating that the potential energy curves are not changed much upon electronic excitation. We conclude that the small structural change is the main cause of its slow radiationless transition and high fluorescence quantum yield at the zero-vibrational level in the S1 state. It has been already reported that the lifetime of perylene is remarkably short at specific vibrational levels in the S1 state. Here, we show that the mode-selective nonradiative process is internal conversion (IC) to the S0 state, and the ν16(a g ) in-plane ring deforming vibration is the promoting (doorway) mode in the S1 state which enhances vibronic coupling with the high-vibrational level (b 2u ) of the S0 state.  相似文献   

12.
Using Lie group theory, both the invariants and the similarity variables of the complex Ginzburg—Landau equation Vxx = a(Vt + bV) + cV|V|2kwherea,b,c?Iandk?I are constructed.  相似文献   

13.
The 3A2(nπ*)→1A1X (T1S0) phosphorescence excitation spectrum of jet-cooled xanthione was investigated in the region 14 920-17 600 cm−1. The structure observed is shown to be due to the T1S0 absorption and an assignment in terms of the vibronic structure of that band is proposed. A previous assignment of the S1S0 origin is considered in detail and the transition involved is shown to be most probably due to absorption of a vibronic triplet state T1z,ν7. An alternative but tentative assignment of the S1,0S0,0 transition is suggested. Comparison is made with previous spectroscopic and theoretical work on the molecule and its congeners, 4H-pyran-4-thione and 4H-1-benzopyran-4-thione.  相似文献   

14.
A theoretical model is developed to account for the effect of diffusion on gain saturation in gas lasers. It is shown that the effect can be characterized by the functionK(k 2 a, k 2 b), which depends on pressure, temperature, radius of the beama, and the radius of the cylindrical cavityb. It is concluded that diffusion can be very effective whenk 2 a is small andb is several times larger thana.  相似文献   

15.
We extend some recent results of Lubinsky, Levin, Simon, and Totik from measures with compact support to spectral measures of Schrödinger operators on the half-line. In particular, we define a reproducing kernel S L for Schrödinger operators and we use it to study the fine spacing of eigenvalues in a box of the half-line Schrödinger operator with perturbed periodic potential. We show that if solutions u(ξ, x) are bounded in x by ${e^{\epsilon x}}We extend some recent results of Lubinsky, Levin, Simon, and Totik from measures with compact support to spectral measures of Schr?dinger operators on the half-line. In particular, we define a reproducing kernel S L for Schr?dinger operators and we use it to study the fine spacing of eigenvalues in a box of the half-line Schr?dinger operator with perturbed periodic potential. We show that if solutions u(ξ, x) are bounded in x by eex{e^{\epsilon x}} uniformly for ξ near the spectrum in an average sense and the spectral measure is positive and absolutely continuous in a bounded interval I in the interior of the spectrum with x0 ? I{\xi_0\in I}, then uniformly in I,
\fracSL(x0 + a/L, x0 + b/L)SL(x0, x0)? \fracsin(pr(x0)(a - b))pr(x0)(a - b),\frac{S_L(\xi_0 + a/L, \xi_0 + b/L)}{S_L(\xi_0, \xi_0)}\rightarrow \frac{\sin(\pi\rho(\xi_0)(a - b))}{\pi\rho(\xi_0)(a - b)},  相似文献   

16.
Thermopower of the ambient pressure organic superconductor β-(BEDT-TTF)2I3 has been studied. Measurements performed on, respectively, crystals of needle formed morphology and on flake-like crystals with hexagon shape showed equal thermopower results. S was measured along the a-axis as well as along the b′-axis. Marked anisotropy is observed in the entire temperature region studied. The temperature dependence, as represented by dS/dT, is, however, nearly isotropic. On the basis of an analysis of anisotropic thermopower we attribute the isotropic part of S to a term depending on the bond-properties and the anisotropic part of S to the scattering mechanism. The analysis yields transfer integrals of the order of 0.12 eV along both a- and b′-axes.  相似文献   

17.
Resonant absorption of microwaves in CuGeO3 single crystals in a frequency band of 40 to 120 GHz, in magnetic field B⩽15 T, at temperatures ranging between 0.5 and 300 K, and in the configuration Ba has been investigated. Several absorption lines (S 0, S a, and S b) whose parameters strongly depend on temperature have been detected close to ESR. The temperature dependence of the total absorption in the main line S 0 with the Landé g-factor g 0=2.154 at temperatures above the spin-Peierls transition temperature is in good agreement with Bonner and Fisher’s theoretical prediction for a one-dimensional Heisenberg spin chain. In addition to the main resonance, a resonance of smaller amplitude, S a, with the g-factor g a=2.72 has been detected at temperatures ranging down to a characteristic temperature T≃1 K, below which the amplitude of this feature drops to zero. A radical restructuring of the magnetoabsorption spectrum occurs at the temperature of the spin-Peierls transition T SP≈14 K. At T<12 K new features emerge in the spectrum, namely, a broad absorption line overlapping with the narrow lines S 0 and S a, and a line S b with g b=1.83, which is not detected at temperatures above T SP. An analysis of amplitudes and total absorption of ESR lines as functions of temperature has shown that the temperature range below 1 K is anomalous, which may be caused by an additional ordering in the CuGeO3 magnetic subsystem at low temperatures. Zh. éksp. Teor. Fiz. 112, 1727–1738 (November 1997)  相似文献   

18.
The dipole moments of vibronic transitions P 0R caused by vibronic-spin-orbit coupling along the coordinates of out-of-plane vibration modes R (to which the most intense vibronic lines of the fine-structure phosphorescence spectrum correspond) were calculated for the 3 B 1u (π π*) → S 0 electronic transition in an octachlorodibenzo-p-dioxin molecule. The dependence of distribution (P 0R )2 over R on the constant of spin-orbit coupling ?A in different atomic groups (A = C, O, α-Cl, and β-Cl) of the molecule is ascertained. The contribution of these atomic groups (related to ?A) to the value of P 0R i for the transitions from various triplet i-sublevels of the electronic state is determined. The obtained results about the different effect of the α-Cl and β-Cl atoms on the vibronic P 0R i and pure electronic transition dipole moments are discussed in connection with experimental data on the weak influence of the amount of chlorine atoms in polychlorinated dioxins on the phosphorescence decay time.  相似文献   

19.
The electronic—vibrational fluorescence spectra of the first, S01Lb, and second, S01La, electronic transitions of 7-azaindole and its tautomer for an isolated state have been calculated. Specific features of structural changes in 7-azaindole and its tautomer upon electronic excitation are determined. Vibrational spectra are assigned for the ground state, and the vibrational structure of fluorescence spectra is interpreted. It is shown that the intensity redistribution between the 6a and 6b oscillations, which is observed in the fluorescence spectrum of the S01Lb transition in 7-azaindole, can be explained as a result of intensity borrowing (according to the Herzberg—Teller mechanism) from the 1La state.  相似文献   

20.
A detailed vibrational analysis of the 5515 Å absorption of s-tetrazine (tetra-azabenzene) vapor is attempted. More than 80% of the total intensity of the system can be accounted for by band assignments to a single allowed electronic transition, 1B3u-1Ag. The only progression-forming vibration in absorption in ν6a. Three progressions in ν6a account for all intense cold bands. Isotopic shifts of bands lead to convincing assignments of the two excited-state vibrations upon which ν6a progressions are based, namely ν6b and ν8a. It is shown that in all probability the antisymmetric mode ν6b is prominent because of vibrational (Fermi) resonance rather than because of vibronic interactions.  相似文献   

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