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1.
Ab initio calculations in the “first-order wavefunction” CI approximation have been performed for several states of N2+ with 2Σu+, 2Σu?, 4Πu symmetry. A calculation of the electronic factor of the vibronic interaction between the B2Σu+ and C2Σu+ states seems to support the suggestion of Tellinghuisen and Albritton that the C state is predissociated by the continuum of the B state through nuclear momentum coupling. 相似文献
2.
Benedict D. Fabian Thomas P. Fehlner Ling-Shine J. Hwang Jay A. Labinger 《Journal of organometallic chemistry》1980,191(2):409-413
The He(I) photoelectron spectra of (η5-C5H5)Fe(CO)2R, where R = CH3, η1-C3H5 and η1-C5H5, have been recorded. The lowest lying ion states result from ionization of molecular orbitals with large Fe 3d character; these move to lower anergy when R places double bonds in an allylic relationship to the metal atom. The cyclic voltammetric oxidation potential correlates well with the energies of the lowest ion states. A significant interaction between olefin π orbitals and the allylic metal center is proposed. 相似文献
3.
Giannoula Theodorakopoulos Ioannis D. Petsalakis Cleanthes A. Nicolaides Robert J. Buenker 《Chemical physics》1985,100(3)
Oscillator strengths for transitions between the
1A1 ground state of water and its
1A1 and
1A1 excited states are computed employing two different theoretical approaches. In one series of calculations a common orthonormal one-electron basis is employed for all of the above states, while in the other type of treatment two different, mutually non-orthogonal, sets are used; the multireference single- and double-excitation (MRD CI) method is employed in each case, with configuration selection, to generate the various electronic wavefunctions. It is found that the use of ground-state SCF MOs leads to poor convergence in the wavefunctions of the (Rydberg-type)
1A1 and
1A1 excited states and consequently also for the corresponding
---
and
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f-values; this behavior is seen to be closely related to the near degeneracy of the two excited states, each of which is a mixture of the 3a1 → 3sa1 and 1b1 → 3pb1 configurations. Analogous computations with the
1B11b1 → 3sa1 MOs show much better convergence properties, and the resulting f-values compare well with what is obtained when state-specific orbital sets are employed separately for ground and excited states and non-orthonormal techniques are applied to compute the desired transition moments. These results tend to confirm previous findings which indicate conceptual and computational advantages for the calculation of excited-state wavefunctions and properties within the context of a state-specific theory. They also show that although the goal of eliminating the dependence of MRD CI calculations on the choice of MO basis is very nearly approached for energy quantities, it is less satisfactorily achieved for other properties, especially when the existence of nearly degenerate electronic states is a critical factor. 相似文献
4.
Lifetimes have been measured for the Σ and Π vibronic Ã2A1 states of H2S+ by studying the decay curves of the Ã2A1 (0, υ′2, 0) → X? 2B1 (0, υ″2, 0) emission bands. The vibronic Ã2A1 states are produced via excitation of H2S molecules by 150 eV electrons. The Σ sublevels 1 ? υ′2 ? 7 and the Π sublevels 3 ? υ′2 ? 6 have been considered. Predissociation occurs in the Σ sublevels for υ′2 ? 7 and in the Π sublevels for υ′2 ? 6. The obtained radiative lifetimes for the non-predissociated Σ and Π sublevels are around 4.2(±0.4) × 10?6 s and 5.6(±0.5) × 10?6 s respectively. For the predissociated Σ(0, 7, 0) and Π(0, 6, 0) levels the corresponding lifetimes are 2.3(±0.3) × 10?6 s and 1.6(±0.3) × 10?6 s respectively. The rate constant for collisional deactivation (quenching) of the vibronic Ã2A1 states by H2S molecules was found to equal 2.3(±0.3) × 10?9 cm3 mol?1 s?1. 相似文献
5.
Simultaneous emissions from S1(n,π*) and S2(n,π*) states in 3,6-diphenyl-s-tetrazinc (DPT) have been observed along with weak luminescence from T1 (n,π*). The occurrence of the S2(n,π*) fluorescence has been justified on the basis of the slow S2 XXX S1 internal conversion resulting from the large energy gap between the two states. This is the first case of dual fluorescence where both the emitting states are of (n,π*) nature. 相似文献
6.
Lifetime measurements have been performed for two vibrotational levels of the A 0u+ states of the 130Te2 molecule, excited by the 496.5 相似文献
7.
An ICR spectrometer fitted with synchronous photon counting equipment is used to study the emission produced by near-thermal (? 0.1 eV) collisions between He+ and H2O (D2). Within the investigated wavelength region, 185 to 500 nm, the only significant emission features are the A3Π (υ' ? 3) → X3Σ? bands in OH+ and OD+, and the A2Σ+ → X2Π(0.0) band in OH and, possibly, in OD. The corresponding excitation rate constants represent only ? 2% of the total He+/H2O (D2O) charge transfer. The resonant electron-jump model for thermal-energy charge exchange is discussed in the light of recent information on the He+/H2O reaction and on the excited states of H2O+ and their excitation by electron and photon impact on H2O (D2O). 相似文献
8.
J.P. Flamme H. Wankenne R. Locht J. Momigny P.J.C.M. Nowak J. Los 《Chemical physics》1978,27(1):45-49
The metastable transitions producing CH33/CH4 and CD3+/CD4 have been investigated by means of translational spectroscopy. For the first time structures are observed in a metastable peak corresponding to the dissociation of a polyatomic ion. They are interpreted by tunneling through a rotational barrier from discrete quasi-bound states. Kinetic energy releases have been measured. 相似文献
9.
Lifetimes and Landé factors were measured for rovibronic levels of the A Ou+ and B Ou+ states of 130Te2 excited by 514.5.496.5 and 488.0 nm Ar+-laser lines. Effective relaxation cross sections were obtained for collisions with 130Te2. 相似文献
10.
Ab initio calculations are performed to obtain potential energy curves for the X1Σg+ state of Li2 and Na2 and the X2Σg+ and A2Σg+ states of their anions. The A2Σg+ M2? curves are found to intersect the X1Σg+M2 curves at low energies and are expected to play a major role in the e? + M2 → M? + M process. 相似文献
11.
Charles E. Hudson David J. McAdoo 《Journal of the American Society for Mass Spectrometry》2008,19(10):1491-1499
1,2-Eliminations are a varied and extensive set of dissociations of ions in the gas phase. To understand better such dissociations,
elimination of CH2=CH2 and CH3CH3 from (CH3)2NH+CH2CH3 (1) and of CH4 from (CH3)2NH2+ are characterized by quantum chemical calculations. Stretching of the CN bond to ethyl is followed by shift of an H from
methyl to the bridging position in ethyl and then to N to reach (CH3)2NH2+ + CH2=CH2 from 1. CH3CH3 elimination by H-transfer to C2H5+ to form CH3NH+=CH2 + CH3CH3 also takes place. (CH3)2NH2+ eliminates methane by CN bond extension followed by β-H-transfer to give CH2=NH+ + CH4. Low-energy reactions resembling complex-mediated 1,2-eliminations occur and constitute a hitherto largely unrecognized type
of reaction. As in many complex-mediated reactions, these reactions transfer H between incipient fragments. They are distinguished
from complex-mediated processes by the fragments not being able to rotate freely relative to each other near the transition
state for reaction, as they do in complexes. Most 1,2-eliminations are ion-neutral complex-mediated, occur by the just described
lower energy reactions, have 1,1-like transition states, or utilize highly asynchronous 1,2 transition states. All of these
avoid synchronized 1,2-transition states that would violate conservation of orbital symmetry. 相似文献
12.
Using an MC SCF CI method, wavefunctions for the ground state 1∑+g and the excited states of the symmetries 1∑+g, 1Πg, and 1Δg of the Cs2+2 ionic system are generated. The potential curves for eleven 1∑+g twelve 1Πg, and six 1Δg states are calculated. Results suggest a small charge-transfer cross section for the reaction CS+ + Cs+ → Cs CS2+. 相似文献
13.
Giannoula Theodorakopoulos Cleanthes A. Nicolaides Robert J. Buenker Sigrid D. Peyerimhoff 《Chemical physics letters》1982,89(2):164-170
The minimum energy pathways for symmetrical dissociation of water into O(1Dg + H2(X1Σ+g) are calculated by the MRD Cl technique for various excited states of H2O and possible mechanism for the photodissociation are discussed. 相似文献
14.
CAS SCF CI (SD) calculations have been carried out for the 3Σ?g, 1Σ+g, 3Σ+u, and 5Δu states of Sc2 using large gaussian basis sets. The 3Σ?g, 1Σ+g, and 3Σ+u states arise from the 2D(4s2 3d1) + 2D(4s2 3d1) limit of Sc2 and are found to be only weakly bound (Dc ≈ 0.06 eV and Rc ≈ 8.0a0). The 5Δu state arises from the 2D(4s2 3d1) + 4F(4s1 3d1 4p1) atomic limit. This state is found to be strongly bound relative to its limits (Dc ≈ 0.8 eV and Rc ≈ 7.0a0). 相似文献
15.
The results of quantum chemical calculations of the electronic structure and geometry of octahedral clusters [Mo6S8(CN)6]6−, [Mo6Se8(CN)6]6−, [Re6S8(CN)6]4−, and Rh6(CO)16 by the ab initio SCF (RHF) and DFT (B3LYP) methods with various basis sets are presented. The electronic states of the clusters under study
in ideal spherically symmetric potential were classified in the orbital quantum number l (1s, 1p, 1d, 1f, 1g, 1h, 1i), l = 0–6. In real crystal field with Oh symmetry these states are split. The calculated new electronic states were matched to the irreducible representations of
the point symmetry group Oh. The polarizabilities of the compounds considered are 55–65 Å3. A new model for the electronic structure of octahedral clusters containing M6 groups was proposed. The model is based on the idea of free electrons moving in spherically symmetric potential field.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2617–2624, December, 2005. 相似文献
16.
Chemiluminescence studies of the reactions of microwave-discharged oxygen with SbBr3 have led to the observation of some band sequences in the near infrared region which are attributed to b0+ → X10+ and b0+ → X21 transitions of SbBr. Analysis of the spectra yielded Te values for the X21 and b0+ states of 874 ± 10 and 12756 ± 10 cm?1, respectively, and vibrational frequencies in the X10+, X21 and b0+ states of ω′'e(X1, X2) = 257 ± 10 and ω′e(b) = 270 ± 10cm?1. 相似文献
17.
New emission systems have been observed from the helium afterglow reaction of GeH4 in the 520–610 nm region. On the basis of the rotational analysis, they were assigned to the a 3Π0+-X1Σ+ and a3Π1-X1Σ+ subsystems of GeH+. Spectroscopic constants have been determined for the GeH+ (a3Π0+, a3Π1, X1Σ+) states. 相似文献
18.
A pulsed ICR cell fitted with synchronous photon counting equipment is used to investigate the emission produced between 185 and 500 nm by near-thermal charge exchange between He+ and C2H2 (C2D2). The emission bands observed are A 2Δ → X2π and (weakly) B2Σ? → X2π in CH(CD) and A 1π → X1Σ in CH+(CD+). Wavelength measurements on the bandheads of the (0,0) and (0,1) bands of CD+ A → X are used to evaluate vibrational constants of CH+(CD+) X1Σ+. The results are (in cm?1): ωe = 2869 ± 27 (2106 ± 20); ωeχe = 65 ± 13 (35 ± 7). These constants are used to calculate Morse-potential Franck—Condon factors and vibrational branching ratios for CH+ and CD+ A → X emission. The spectral distributions and the (relatively low) absolute emission rates produced by He+/C2H2(C2D2) charge exchange are briefly discussed in the light of presently available information on the charge transfer reaction and on the excited states of C2H2?+ 相似文献
19.
Autoionizing Rydberg series of Li2 have been observed in the two-step optical cxcitation of a supersonic lithium beam. The series limits are vibrational states of Li2+. In the most probable assignment IP(Li2) = 41236.4 ± 2.5 cm?1 and for Li2+ωe = 263.45 ± 1.3 cm?1; ωeχe = 1.35 ± O.2 cm?1; re = 3.032 ± 0.01 Å; De = 10807 ± 150 cm?1. 相似文献
20.
Marek Z. Zgierski 《Chemical physics letters》1980,69(3):608-610
The recently observed T1 ← SO excitation spectra of triphenylene-h12 and -d12 are analysed in terms of interstate pseudo-Jahn-Teller and intrastate Jahn-Teller coupling of the two lowest triplet states, T1 [3A'2(ππ1)] and T2[3E'(ππ*)], via an e' mode. 相似文献