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1.
The equilibrium geometries, excitation energies, force constants, and vibrational frequencies of the low-lying electronic states X2B1, 2A1, 2B2, and 2A2 of the PF2 radical have been calculated at the MRSDCI level with a double zeta plus polarization basis set. Our calculated geometry, force constants, and vibrational frequencies for the X2B1 state are in good agreement with experimental data. The electronic transition moments, oscillator strengths for the 2A1X2B1 and 2A2X2B1 transitions, and radiative lifetimes for the 2A1 and 2A2 states are calculated based on the MRSDCI wave functions. © 1994 by John Wiley & Sons, Inc.  相似文献   

2.
Ab initio electronic structures calculations are reported for the four low-lying electronic states X 2B1, 2B2, 2A2, and 2A1 of the CH2NO2 radical. The geometric parameters for the ground-state X 2B1 are predicted by MRSDCI calculations with a double zeta plus polarization basis set. The vertical excitations energies for these electronic states are determined using MRSDCI /DZ +P calculations at the ground-state equilibrium geometry and in agreement with the recent experimental data obtained via PES of the CH2NO anion. The oscillator strenghts and the radiative lifetimes for these electronic states and the spin properties for the ground state are calculated based on the MRSDCI wave functions, predicting results in good agreement with available experimental data. © 1994 John Wiley & Sons, Inc.  相似文献   

3.
The equilibrium geometries, excitation energies, force constants, and vibrational frequencies for four low-lying electronic states X 2A1, 2B1, 2B2, and 2A2 of the BF2 radical have been calculated at the MRSDCI level with a double zeta plus polarization basis set. Our calculated excitation energy for X2A12B1 is in agreement with available experimental data. The electronic transition dipole moments, oscillator strengths for the 2B1X2A1 and 2B2X2A1 transitions, radiative lifetimes for the 2B1 and 2B2 states, and the spin properties for the X2A1 state are calculated based on the MRSDCI wave functions, predicting results in reasonable agreement with available experimental data. © 1993 John Wiley & Sons, Inc.  相似文献   

4.
Summary Restricted Active Space (RAS) SCF calculations have been performed of the potential curves for theX 3 andA 3 states of the OH+ ion and on the lifetime of thev=0–2 vibrational levels of theA state. The convergence of the transition moment integral as a function of the size of the active orbital space was used to select the active orbitals. The calculated value of thev=0 lifetime is 2.4 µs. An estimate of the errors remaining in the calculation leads to a final theoretical value of 2.7±0.1 µs. Computed bond distances and bond energies are 1.031 (1.029) Å and 5.05 (5.01) eV, respectively, for theX state, and 1.137 (1.135) Å and 1.57 eV, respectively, for theA state (experimental values within parenthesis).On leave from Departamento de Quimica Fisica, Universitat de València, Dr. Moliner 50, Burjassot, 46 100 València, Spain  相似文献   

5.
Configuration interaction (CI) studies of the ground and electronically excited states are reported for nitric oxide dimer (N2O2) in itscis equilibrium geometry. The lowest triplet state (3 B 2) is found to lie only 0.43 eV above the ground state (1 A 1). The1 A 1 1 B 1 transition is shown to be responsible for the rising absorption in the near infrared region observed experimentally. The transition of1 A 11 A 2 calculated in the visible spectrum range of 701 nm (1.77 eV) is symmetry forbidden.  相似文献   

6.
The two lowest electronic states (3 B 1 and 1 A 1) of the methylene radical (CH2) are calculated both in SCF-approximation and with the IEPA-PNO method (including electron correlation). The influence of polarization functions and electronic correlation on the shape of the potential curves of the two states is discussed. The calculated equilibrium geometries agree very well with experiment, but the results for transition energies (e.g. 3 B 11 A 1 excitation energy=9.2 kcal/mole, total binding energy=187 kcal/mole) are more reliable than the existent experimental values.  相似文献   

7.
Ab initio electronic structure calculations are reported for low-lying electronic states, 1A1, 1A2, 3A2, 1B1, 3B1, 1B2, and 3B2 of the FNO2 molecule. Geometric parameters for the ground state 1A1 are predicted by MRSDCI calculations with a double-zeta plus polarization basis set. The vertical excitation energies for these electronic states are determined using MRSDCI/DZ+P calculations at the ground-state equilibrium conformation. The oscillator strengths and radiative lifetimes for some electronic states are calculated based on the MRSDCI wave functions. © 1993 John Wiley & Sons, Inc.  相似文献   

8.
The oscillator strengths of the symmetry-forbidden transitions of the ion [PdCl4]2– were calculated by a method based on the evaluation of the MO of the distorted ion. It is not very likely that the transition to1 B 1g (a 1g (d z 2)b 1g ) state, weak, mainlyz polarized, explains the band that appears as a shoulder observed towards 30 000 cm–1 in the absorption spectrum. If this band is specific of the ion [PdCl4]2–, the assignment to the forbidden charge-transfer transition,1 A 1g 1 B 2g , is more plausible.
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9.
Molecular structure and properties of La and Lu tetrahalide ions LnX 4 ) are studied by the configuration interaction singles-and-doubles method augmented with quadruple excitation correction (CISD+Q) and by the fourth-order Möller-Plesset perturbation theory with account for single, double, triple, and quadruple excitations (SDTQ-MP4). The atomic inner shells are described by Stevens relativistic effective core potentials. Valence basis sets are augmented with diffuse s-, p-, and polarization d-, f-, and g-functions. The equilibrium configuration of nuclei in LnX 4 ions was found to be tetrahedral. The equilibrium internuclear distances, quadratic force constants, vibrational frequencies, and IR intensities of LnX 4 ions are compared with the corresponding parameters of La and Lu trihalide molecules (LnX3), calculated within the same approximations. Regularities in the behavior of molecular parameters on going along the LnF 4 LnCl 4 LnBr 4 LnI 4 series and from La compounds to Lu compounds are revealed. Heights of the energy barriers to the LnX 4 inversion through the square planar structures (T d D 4h T d ) are evaluated: 100–110 and 130–150 kJ/mol for LaX 4 and LuX 4 , respectively. Enthalpies of dissociation reactions LnX 4 LnX3+X are calculated and the results obtained are compared with the available experimental data.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 218–228.Original Russian Text Copyright © 2005 by Solomonik, Smirnov, Mileyev.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.  相似文献   

10.
Theoretical vibronic S1S0 line spectra of the isomeric phenyl naphthalenes calculated within the Condon as well as the Herzberg-Teller approaches on the basis of completely optimizedS 0 andS 1 molecular geometries, are presented and are contrasted with the experimental fluorescence spectra. The theory-experiment comparison is successful only within the Herzberg-Teller approximation by explicitly including the Dushinsky transformation. An analysis of the significant vibrational modes is given.  相似文献   

11.
The emission band spectra of S, molecule (B3 u X3 g transition) and of SO molecule (A3 X3) were detected in SF6 and SF6-O2 rf discharges. It has been observed that the presence of a material which can be etched by SF6 products considerably enhances the density of S2 in the reactor. By means of mass spectrometry it has been shown that the m/e =83 mu signal assigned to S2F4 ions evolves exactly in the same manner as the S2 band intensity during the etching of Si or W in SF6-O2 discharge. A reaction scheme involving S2F radicals is proposed to explain these experimental results.  相似文献   

12.
UV/Vis-spectra of Cyclosilanes (SiX 2) n withX=Cl, Br, I, OMe andn=4, 5, 6 are recorded and interpreted qualitatively. The spectra exhibit increasing influence of the substituents on the Si-Si-bond system within the rings in the order Cl OMe Br I. At the low energy side of the spectra weak absorption bands, possibly due to intramolecular charge transfer transitions, appear. The strong inductive effect of the electronegative substituents is documented by a marked increase of the first IP's compared to permethylcyclosilanes.
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13.
Summary New oxomolybdenum(V) complexes MoOCIL (where LH2 = Schiff base) derived from ethanolamine and salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3-ethoxysalicylaldehyde and 2-hydroxy-1-naphthaldehyde have been synthesized and characterised by elemental analyses, conductance, molecular weight, i.r. and electronic spectra and magnetic measurements. The Schiff bases behave as dibasic tridentate ONO donor ligands. The complexes are non-electrolytes and dimers. The complexes exhibit subnormal magnetic moments and are involved in antiferromagnetic exchange withS=0 ground state. The complexes exhibit electronic spectral bands atca. 13000 andca. 17000 cm–1 due to the transitionsd xy d xz,yz (2B2 2E) andd xy d x 2–y2 (2B2 2B1), respectively. The (Mo=O) frequency of the complexes is observed in the 900–970 cm–1 region. On the basis of the magnetic susceptibility, i.r. and molecular weight data a dimetallic structure with alcoholic oxygen atoms as the bridging atoms is suggested.Abbreviations sal salicylaldehyde - 5-chlorosal 5-chlorosalicylaldehyde - 5-bromosal 5-bromosalicylaldehyde - 5-nitrosal 5-nitrosalicylaldehyde - 3-ethoxysal 3-ethoxysalicylaldehyde - hydroxy 2-hydroxyl-1-naphthaldehyde  相似文献   

14.
Rare gas hydride molecules and triatomic hydrogen molecules were produced in a Cossart-type plasma beam Penning tube specially designed for laser spectroscopic work. A cw dye laser was used to stimulate transitions from theB 2 rovibrational levels to theA 2+ levels of argonhydride (40ArH) and argondeuteride (40ArD). The transitions were detected by measuring the decrease of the spontaneous emission from the upper levels, which clearly shows the expected population inversion between the two participating electronic states. With this first laserspectroscopic work on argonhydride and argon deuteride, the classification of the lines of theB 2 A 2+ band as given by Johns 1970 could be checked and was found to be consistent*. Furthermore theQ branches of these bands for ArH and ArD could be completely resolved into their single lines and their wavelengths were measured. The latter allowed the difference between the rotational constants of theA andB electronic states to be directly determined. The method was also applied to triatomic hydrogen. D3. It should be useful for classifying more complicated bands of ArH and of KrH and XeH, which can also be produced in this tube.In later theoretical work theB 2 state was called 22 state [13] andE 2 state [12], respectively  相似文献   

15.
The phosphorescence spectrum of p-dichlorobenzene has been calculated using multiconfiguration self-consistent-field wave functions and the quadratic response technique. Attention has been paid to the intensity distribution of the singlet–triplet (3B1u1Ag) transition through a number of vibronic subbands. The second order spin–orbit coupling (SOC) contribution to the spin splitting of the 3B1u (3*) state is found to be almost negligible, and the calculations therefore provide a good estimate for the zero-field splitting (ZFS) parameters based only on the electron spin–spin coupling expectation values. Nuclear quadrupole resonance constants for the different Cl isotopes are also calculated to accomplish the ZFS assignment. The electric dipole activity of the spin sublevels in the triplet–singlet transitions to the ground-state vibrational levels is estimated by calculations of derivatives using distorted geometries which are shifted from the equilibrium position along different vibrational modes. A vibrational analysis of the phosphorescence spectrum, based on the SOC-induced mixing of the singlet and triplet states calculated along different vibrational modes, provides reasonable agreement with experimental data.Acknowledgment O. R.-P. would like to thank the European MOLPROP network for support. The authors thank Alexander Baev for fruitful discussions. This work was supported by the Swedish Royal Academy of Science (KVA).  相似文献   

16.
Three minor partially acetylated glycosides have been isolated from the leaves of Algerian ivy, Hedera canariensis Willd. (Araliaceae) — the previously known {3-O-[-L-rhamnopyranosyl-(12)-O--L-arabinopyranoside] 28-O-[-L-rhamnopyranosyl-(14)-O-(6-acetyl--D-glucopyranosyl)-(16)-O--D-glucopyranoside}s of oleanolic acid and of hederagenin (ciwujianoside C4 and kizuta saponin K11) and the new 3-O-[-L-rhamnopyranosyl-(12)--O-L-arabinopyranoside] 28-O-[-L-rhamnopyranosyl-(14)-O-(6-O-acetyl--D-glucopyranosyl)-(16)-O--D-glucopyranoside of echinocystic acid (glycoside L-G0). The structures of the glycosides isolated have been established on the basis of chemical transformations and1H and13C NMR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 81–86, January–February, 1999.  相似文献   

17.
Electron transitions in divinyl chalcogenides (CH2=CHXCH=CH2, where X is S, Se, or Te) have been analyzed using UV absorption spectra of dialkyl and alkyl vinyl chalcogenides. The following relations for the orbital energies are found: * < * < * < * for Te and * < * < * < * for S and Se. For chalcophenes, a correlation between the energy of the excited state (E *) of specific symmetry, the ionization potential (I) and the electron affinity (EA) is obtained:E *=const+(I+EA)/2. The electron affinity of divinyl chalcogenides is estimated. The correlation between the excited * states of divinyl chalcogenides and chalcophenes is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–835, May, 1994.  相似文献   

18.
Time-dependent HF (RPA) calculations have been performed to estimate the transition energies and excited state wavefunctions of Li, Be+, B2+ and C3+ for the transitions 1s 22s 2 S 1s 2 ns 2 S (n = 3,4, ... 8). The excitation energies and excited state wavefunctions are extracted from the position of the poles of a linearised variational functional. The excitation energies are in excellent agreement with those obtained spectroscopically. The excited state wavefunctions are utilised to find the matrix elements of different operators and the cusp values.  相似文献   

19.
Summary The three-dimensional potential energy functions have been calculated from highly correlated multireference configuration interaction electronic wavefunctions for theX 3 B 1,a 1 A 1, andb 1 B 1 states of the NH 2 + ion. For the quasi-linear electronic ground state this information and the electric dipole moment functions have been used to calculate spectroscopic constants, line intensities and rotationally resolved absorption spectra. For thea 1 A 1-b 1 B 1 bent/quasi-linear Renner-Teller system ro-vibronic energy levels have been obtained from a variational approach accounting for anharmonicity, rotation-vibration and electronic angular momenta coupling effects. The vibronic levels are given for energies up to 13 500 cm–1 for the bending levels and up to 8000 cm–1 for the stretching and combination levels.Dedicated in the honor of Prof. Werner Kutzelnigg  相似文献   

20.
Line strengthsS for the dipole allowed transitions within then=2 complex of the carbon isoelectronic sequence have been fitted in the formZ 2 S=A+B/(ZC), whereZ is the nuclear charge of a particular ion. The constantsA,B andC are determined by using a non-linear least square method. The data forS is taken from the configuration interaction calculations which included internal, semi-internal and all external type correlations for ions in the rangeZ=8–26. It is shown that the values ofA obtained from the fit for all the transitions are in excellent accord with the ab-initio values obtained in the hydrogenic limitZ provided near degeneracy effects are included.  相似文献   

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