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1.
The electronic spectra of the C 3H ? and C 3D ? anions have been studied above the lowest electron detachment threshold. On the basis of the vibrational, rotational analysis and ab initio calculations, the photodetachment spectrum is assigned to the d 3 A″←a 3 A″ Feshbach resonance in the bent chain C 3H(D) ? anion. The vibronic system is characterized by a long vibrational progression involving the CCH in plane bending mode ν 4. The potential curves along this coordinate obtained from the spectral analysis and theoretical calculations reveal the importance of vibronic coupling in the electronic excited states. A strong Renner–Teller effect is thought to be the reason for the existence of the Feshbach resonance because the 4Σ ? neutral parent and the 3Π anion excited states are close in energy. As for the neutral, ν 4 appears to be the active mode and drives the interaction between the Feshbach and the dipole bound states. 相似文献
2.
依据量子理论与配位场理论,利用群论和对称性分析的方法探讨了C 2+4分子在具有 D4h对称性构型时, E×(b 1g+b 2g)系统的Jahn-Teller效应中的相关问题.研究了C 2+4分子的电子态与声子态的对称性及其活跃声子态,讨论了系统声子间的耦合与CG系数,构建了 E×(b 1g+b 2g
关键词:
2+4分子')" href="#">C2+4分子
对称性
能级分裂
Jahn-Teller畸变 相似文献
3.
An additional term in the effective Hamiltonian for a molecule in a 2S+1Π state subject to a small Renner—Teller effect is derived. It takes the form of a rotational dependence of the Renner—Teller operator and is assigned the parameter ?ω 2,D . This term reproduces two characteristics of the spin—rotational levels of Renner—Teller molecules, both of which are well documented by experimental examples but are not explicable in terms of the previous effective Hamiltonian. These are the small difference between the B values of different vibronic components of the same bending vibrational level and the anomalously strong dependence of the spin—rotation parameter γ on ν 2 for molecules with S > 0. These effects have been explained by previous workers using perturbation theory but in a less general and more complicated fashion. 相似文献
4.
The results of ab initio calculations of the vibronically averaged components of the anisotropic magnetic hyperfine tensor in the low-lying vibronic species of the X 2Π electronic state of the HCCS radical are reported. The electronically averaged hyperfine coupling constants for hydrogen, deuterium, 13C and 33S are obtained as functions of two bending vibrational modes by the density functional theory method. The vibronic wave functions are calculated with the help of a variational approach which takes into account the Renner–Teller effect and spin-orbit coupling. The results of ab initio calculations are compared to the corresponding experimental findings. 相似文献
5.
The vibronic coupling between the first excited S 1 (2 1A g) and the second excited S 2 (1 1B u) singlet electronic states in spectroscopy of trans‐1,3,5‐hexatriene molecule is investigated on the basis of a model consisting of two electronic states coupled by two vibrational modes. Employing a perturbation theory that treats the intramolecular couplings in a perturbative manner, the absorption and resonance Raman cross sections and excitation profiles of this molecule are calculated using the time‐correlation function formalism. The non‐Condon corrections are included in evaluation of cross sections. The multidimensional time‐domain integrals that arise in these calculations have been evaluated for the case in which S 0 (1 1A g) S 2 (1 1B u) electronic transition takes place between displaced and distorted harmonic potential energy surfaces. The calculated spectra are in good agreement with the experimental ones. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
6.
The theory of multiphonon vibronic coupling to electronic transitions is applied in analysing fluorescence spectra of Eu 2+ in BaFCI, which consist of the 4f 7( 6P 7/2,) → 4f 7( 8S 7/2) and 4f 65d → 4f 7 transitions, and the 4f 7-4f 65d excitation spectrum of Ce 3+ in YPO 4. The 4f electrons are weakly coupled to lattice vibration modes so that only weak one- and two-phonon sidebands are observable in the 4f-4f optical transitions, whereas the electron-phonon coupling is significantly stronger for a 5d electron. Accordingly, intensive multiphonon vibronic transitions overwhelmingly dominate the 4f 65d → 4f 7 spectrum. It is shown that the extended Judd-Ofelt theory for weak vibronic coupling in the framework of the M-process is equivalent to the Huang-Rhys theory for the δ-process. In the analysis of experimental data, contributions from local ligand modes and lattice acoustic modes are separated, and the coupling strength is evaluated, in terms of the Huang-Rhys parameter S, for the 4f-4f and 5d-4f vibronic transitions. 相似文献
7.
The absorption and MCD spectra of the 3A2g → 1Eg transition of CdI 2:Ni 2+ at about 12,500 cm ?1 have been measured. The unusual vibronic fine structure is explained by the coupling of the phonons of the CdI 2 lattice to the electronic states of Ni 2+. The dispersion curves for the acoustical and optical branches in the Brillouin Zone of CdI 2 are deduced. 相似文献
8.
基于完全对角化方法(complete diagonalization method, CDM), 研究了 6S(3d 5)态离子在立方对称晶场中的磁相互作用,分析了自旋哈密顿参量( a, g,Δ g)的微观起源.研究中除了考虑研究者通常考虑的SO(spin-orbit)磁相互作用外,同时考虑了SS(spin-spin),SOO(spin-other-orbit),OO(orbit-orbit)磁相互作用.研究表明: 6S(3d 5)态离子在立方对称晶场中的自旋哈密顿参量起源于五种机理,即SO机理,SS机理,SOO机理,OO机理以及SO-SS-SOO-OO联合作用机理.文中研究了五种机理的相对重要性,结果表明:SO机理与SO-SS-SOO-OO联合作用机理在五种机理中最为重要.尽管SS,SOO,OO磁相互作用单独作用时对自旋哈密顿参量的贡献很小,但它们的联合作用SO-SS-SOO-OO机理对自旋哈密顿参量的贡献非常可观.此外研究表明:零场分裂参量 a主要来自纯自旋四重态及自旋二重态与自旋四重态联合作用的贡献,而Zeeman g(或者Δ g)因子主要来自纯自旋四重态的贡献.纯自旋二重态对自旋哈密顿参量 a与 g(或者Δ g)的贡献为零.在我们所选择的晶场区域,发现下列关系始终成立: a>0, a(-| Dq|)< a(| Dq|), g(- Dq)= g( Dq), a(- Dq,- ξd, B, C)= a( Dq, ξd, B, C),Δ g(- Dq,- ξd, B, C)=Δ g( Dq, ξd, B, C).作为本文理论的应用,研究了四种典型的Mn 2+掺杂晶体材料,即Mn 2+:KZnF 3,Mn 2+: RbCdF 3,Mn 2+: MgO,Mn 2+: CaO,理论与实验测量符合很好.
关键词:
自旋哈密顿参量
6 S(3d 5)态离子')" href="#"> 6S(3d 5)态离子
磁相互作用
完全对角化方法(CDM) 相似文献
9.
Vibronic coupling in the energetically lowest first four electronic states of CH 2F +2 is studied in this paper. A model 4×4 Hamiltonian is constructed in a diabatic electronic representation employing normal coordinates of vibrational modes and standard vibronic coupling theory. Extensive ab initio quantum chemistry calculations are carried out to determine the parameters of the Hamiltonian and energetic ordering of the electronic states. The topographical features of the latter are examined at length and several conical intersections are established. Nuclear dynamics calculations on coupled electronic states are carried out from first principles by propagating wave packet. Theoretically calculated broad band vibronic structure of the four states are found to be in good accord with the experimental results. 相似文献
10.
The vapor phase fluorescence spectra of p-benzoquinone- h4 and d4 are reported and discussed in relation to the assignment of the low lying singlet states. The low temperature, polarized single crystal electronic absorption spectra of p-benzoquinone and several of its isotopic derivatives are reported. From the isotope shifts and band polarizations of the various vibronic origins, a detailed vibronic analysis is offered of the electronic absorption spectrum of p-benzoquinone which indicates a near degeneracy of the 1Au and 1B1g electronic states. 相似文献
11.
The vibronic couplings of pyrazine- d0 and pyrazine- d4 between the lowest electronic excited states 1B3u( n, π *) and 1B2u(π, π *) through the out-of-plane CH bending vibration ν 10a( b1g) have been studied from the Raman, electronic absorption and fluorescence spectra. The isotope effects on the scattering cross section of the ν 10a Raman line, the vibrational potential in the 1B3u( n, π *) state and on the frequency change of the ν 10a vibration between the ground and the lowest electronic excited states are well explained by conventional Herzberg-Teller coupling mechanism. However, the intensities of the vibronic bands in the electronic absorption and fluorescence spectra are hardly explained with this coupling mechanism. 相似文献
12.
The dependence of the spectra of the near-IR and visible selective heat radiation (SHR) of the Yb 2O 3 polycrystals that are synthesized using the laser thermal method on the excitation intensity of the CW electric discharge
CO 2 laser at the wavelength λ = 10.6 μm is experimentally studied. The SHR spectra are determined by the multiphonon excitation
of the vibronic states of the 2
F
5/2 term in the Yb 3+ ions and the radiative transitions to the vibronic states of the ground term 2
F
7/2.The laser heating of the polycrystals to the melting point causes the anomalous growth of the SHR spectral peaks in the wavelength
range λ ≥ 1040 nm due to an increase in the intensity related to an increase in the probabilities of the radiative vibronic
transitions owing to the thermal increase in the phonon density. The effective conversion of the thermal energy of the Yb 2O 3 polycrystals into the SHR indicate the significant role of the radiative cooling of surface. 相似文献
13.
Spectral optical investigations of two low-dimensional organic molecular conductors with differently oriented conducting layers of ethylenedithiotetrathiafulvalene (EDT-TTF) molecules, namely, the (EDT-TTF)3Hg2Br6 and (EDT-TTF)3Hg(SCN)3I0.5(PhCl)0.5 single crystals, have been carried out. The polarized reflectance spectra of the single crystals have been measured in the frequency range 700–6500 cm−1 (0.087–0.810 eV) at temperatures from 300 to 15 K. The optical conductivity spectra have been obtained using the Kramers-Kronig relations, and their quantitative analysis has been performed in terms of a theoretical model that takes into account electron-electron correlations in the approximation of the Hubbard Hamiltonian for trimerized stacks, the vibronic coupling, and the influence of the counterion on the electronic states in the trimer. A satisfactory agreement between the theoretical and experimental spectra for both crystals made it possible to estimate the parameters of the electronic structure of the crystals in the conducting plane: the integral t of the electron transfer between the EDT-TTF molecules in the trimer, the energy U of the Coulomb repulsion between two electrons (holes) in one EDT-TTF molecule, the electron transfer damping constant γ
e
, the energy shift Δ of the molecular orbital under the influence of the anions and vibronic coupling, the vibronic coupling constant g
n
, and the binding energy E
p
of the molecular polaron. It has been found that there are large differences in the anisotropies of the optical properties and the obtained Hubbard parameters of the electronic structure for the studied crystals. 相似文献
14.
ABSTRACTThe variability of planar rings in Si 4X4 ( X?=?F, Cl, Br, I) molecules caused by the pseudo-Jahn–Teller impact (PJTE) was evaluated as an original PJTE work. Optimisation and the following frequency calculations in these molecules illustrated that in high-symmetry planar (with D4h symmetry) geometry, all of these compounds were unstable and their structures were puckered to lower C2h symmetry stable geometry. Furthermore, the vibronic coupling interaction between 1A1g ground and the first 1Eg excited states through ( 1A1g?+? 1Eg) ? eg PJTE problem was the cause of non-planarity of the four-member ring and the symmetry breaking phenomenon in those series. The calculated gaps (Δ) between the ground state and the Eg excited state, the vibronic coupling ( F) and ground state primary force constant values ( k1) were obtained from the numerical fitting of the ground state adiabatic potential energy surface with the analytical expressions of these molecules. Finally, natural bond analysis (NBO) was used for the design of the strongest interaction and natural atomic charges of these structures. 相似文献
15.
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 S 0 1 A g and S 1 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 S 1 state are very similar to those in the S 0 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 S 1 state. It has been already reported that the lifetime of perylene is remarkably short at specific vibrational levels in the S 1 state. Here, we show that the mode-selective nonradiative process is internal conversion (IC) to the S 0 state, and the ν 16( a g ) in-plane ring deforming vibration is the promoting (doorway) mode in the S 1 state which enhances vibronic coupling with the high-vibrational level ( b 2u ) of the S 0 state. 相似文献
16.
2?+?1 resonance-enhanced multiphoton ionization (REMPI) spectra of allene at 7.0–10.5?eV have been observed. The excited vibronic symmetry has been determined from polarization-ratio measurements. Based on the vibronic energies and peak intensities calculated using ab initio MO and time-dependent density functional theory, the very congested REMPI spectra have been assigned as due to π*?←?π, 3p?←?π, 4s?←?π, 4p?←?π, and 4d?←?π transitions. Vibrational progressions related to the CH 2 twisting (ν 4 ~770?cm ?1) have been observed for several excited electronic states. Calculated Franck–Condon factors also confirm that CH 2 twisting is the most active mode in the vibronic spectra of allene. In this study, theoretical calculations of two-photon intensities and polarization ratios have been made through the ab initio computed one-photon transition dipole moments to various electronic states as intermediates. As a starting point to interpret the complicated vibronic spectrum of allene, the theoretical approach, without vibronic couplings, has been applied to predict the peak positions, spectral intensities, and polarization ratios of Rydberg states, and qualitatively shows a considerable agreement with experimental observations. 相似文献
17.
The single isotropic g factor found in the 2E excited state of ZnS:Cu 2+ is hard to reconcile with the properties of this state, in particular with the moderate strength of the E ? ? vibronic coupling. A vibronic coupling between this state and the vibronic levels of the ground 2T2 state due to τ 2 modes can bring about motional averaging between strain split states of 2E through a two phonon non-resonant process. In general, excited state mechanisms will be effective between states of the same spin multiplicity and which have large Stoke shifts. 相似文献
18.
Laser induced fluorescence (LIF), single vibronic level dispersed fluorescence (DFL) spectra, and high resolution rotationally resolved scans of the S 0–S 1 transition of the C 10H 8 isomer 1-phenyl-1-butyn-3-ene have been recorded under jet-cooled conditions. The S 0–S 1 origin of PAV at 34 922 cm −1 is very weak. A vibronic band located 464.0 above the origin, assigned as 30 10, dominates the LIF excitation spectrum, with intensity arising from vibronic coupling with the S 2 state. High resolution scans of the S 0–S 1 origin and 30 10 vibronic bands determine that the former is a 65:35 a: b hybrid band, while 30 10 is a pure a-type band, confirming the role for vibronic coupling and identifying the coupled state as the S 2 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 S 0 and S 1 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
19.
The visible and near infrared luminescence spectra of MoCl 6 3- in Cs 2Na MCl 6 ( M=Sc, Y, In) and MoBr 6 3- in Cs 2NaYBr 6 have been measured between 15 000 cm -1 and 3000 cm -1 at liquid helium temperatures. Comparison with new electronic absorption, infrared and Raman spectra have enabled five luminescence transitions between the states derived from the t 2g 3 configuration to be assigned unambiguously. Each electronic transition shows extensive vibronic structure which can be analysed to yield the vibrational frequencies of the Mo X 6 3- ion in each state. The spectra are strongly influenced by resonant interactions between the Mo X 6 3- ion and the internal and lattice modes of the host lattices and there is an enormous variation in the intensities of the vibronic origins. 相似文献
20.
In fine-structure phosphorescence spectra of metallocomplexes of porphin with ions of the Pd(II) and Pt(II) and their meso-deuterated derivatives additional lines have been detected which have no analogs in fluorescence and resonance Raman spectra
of metalloporphyrins and in phosphorescence spectra of metallocomplexes of porphin with light ions of the Mg(II) and Zn(II).
For Zn-porphin, quantum-chemical calculations of frequencies and forms of in-plane and out-of-plane vibrations have been performed.
Based on experimental data and calculation results it has been found, that in vibronic phosphorescence spectra of metallocomplexes
of porphin, out-of-plane gerade modes of the E
g
symmetry ( D
4h
symmetry group) are manifested. The activity of out-of-plane vibrations increases with enhancing spin-orbital coupling upon
changing to heavier chelated metal ions. Vibronic transitions with participation of out-of-plane gerade E
g
vibrations manifest in the T
1 → S
0 transition through the vibronic intensity borrowing from the triplet-triplet 3
E
u
- 3
E
g
transition. 相似文献
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