Selection rules and Raman spectrum of a molecule with a degenerate ground state and zero spin-orbit coupling: VCl4

Parameswaran, T.; Koningstein, J. A.; Haley, L. V.

doi:10.1016/0022-2852(77)90293-4

Cited by 11 publications

(4 citation statements)

References 15 publications

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“…The fact that the JT effect in the ground state is much weaker than in the excited LF state is due to the different antibonding character of the e and t 2 molecular orbitals, which is of π and σ + π type for e and t 2 , respectively. In analogy to MnO 4 2- , the JT effect in the 2 E ground state of the isoelectronic VCl 4 complex was found to be very weak; i.e., E JT ( 2 E) is smaller than 100 cm -1 . , For the 2 T 2 ground state of Cu 2+ in Cs 2 CuCl 4 (3d 9 with a hole in the t 2 shell), on the other hand, the JT stabilization energy is E JT ( 2 T 2 ) ≈ 1200 cm -1 and thus strong enough to produce substantial static distortions of the CuCl 4 2- unit . The larger value of E JT ( 2 T 2 ) for CuCl 4 2- than for MnO 4 2- is mainly the result of the smaller force constant for the e bending mode in the copper system.…”

Section: Discussionmentioning

confidence: 95%

Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Brunold

Güdel

1997

Inorg. Chem.

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The first polarized low-temperature absorption and luminescence spectra of manganese-doped crystals of BaSO(4) containing essentially MnO(4)(2)(-) are reported. By using a flux composed of NaCl, KCl, and CsCl we were able to grow BaSO(4):Mn(6+) crystals below 620 degrees C. This prevents the simultaneous presence of MnO(4)(3)(-) besides MnO(4)(2)(-), which was mainly responsible for the erroneous assignments of the absorption spectrum in the literature. In the BaSO(4) host the MnO(4)(2)(-) ion occupies a site of C(s)() symmetry, and the orbital degeneracies of the E and T states are thus lifted. Above 16 000 cm(-)(1) the absorption spectra consist of a series of intense ligand-to-metal charge transfer (LMCT) excitations. Their marked polarization dependence allows an unambiguous band assignment in the parent T(d)() symmetry. The three origins of the (2)E --> (2)T(2) ligand-field (LF) transition peak at 11 074, 11 570, and 11 790 cm(-)(1). The lowest-energy component of (2)T(2) serves as the initial state for broadband luminescence in the near-infrared (near-IR) region with a maximum at 9300 cm(-)(1). Below 100 K the quantum yield is unity and the radiative lifetime is 2.75 &mgr;s, and at 300 K the quantum yield is still 20%. In both the (2)E <--> (2)T(2) (d --> d) absorption and luminescence spectra the vibrational structure is dominated by progressions in O-Mn-O bending modes whereas coupling to the totally symmetric Mn-O stretching mode is less pronounced. The luminescence band shapes for the transitions to the two orbital components of (2)E are strikingly different; the Huang-Rhys parameters for the bending-mode progressions obtained from fits of simulated band shapes to the experimental spectra are 1.3 and 3.7, respectively. This is due to weak E multiply sign in circlee and stronger T(2) multiply sign in circlee Jahn-Teller (JT) effects in the ground and excited LF states, respectively. The linear vibronic coupling constants are f(E)() approximately 180 cm(-)(1) and f(T)() approximately -730 cm(-)(1) and the corresponding JT stabilization energies E(JT)((2)E) approximately 50 cm(-)(1) and E(JT)((2)T(2)) approximately 780 cm(-)(1), respectively.

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Section: Discussionmentioning

confidence: 95%

Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Brunold

Güdel

1997

Inorg. Chem.

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“…For the thermodynamic functions of VC14 we have used the gas phase frequencies determined in Ref. 15, internuclear distance r, (V-Cl) = 2.138 A, and vibronic interaction constant aE = 2.1 determined in Ref.…”

Section: Calculations Of the Thermodynamic Functions For Vanadium Tetmentioning

confidence: 99%

Thermodynamic functions for vibronic systems

Crotov

Ischenko

Ivashkevich

1979

Int J of Quantum Chemistry

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AbstractsA method is introduced which simplifies the derivation of equations for the calculation of statistical sums for vibronic systems. Within the "independent ordering approximation" analytical expressions are found for thermodynamic functions for molecules with degenerate electronic ground state ( E -B and E -e types of degeneracies). Vibronic interactions are shown to yield an additional thermodynamic stabilization. The computations were carried out for VCI, and VBr4 with doubly degenerate electronic ground states. For these molecules the effect is shown to be small.On introduit une mithode, qui simplifie la derivation des tquations pour calculer les sommes statistiques pour des systemes vibroniques. Dans le cadre de I'approximation "des arrangements independants" on a trouve des expressions analytiques pour les fonctions thermodynamiques des molecules avec un Ctat fondamental degtntre (type de digtnerescence E -p et E -e). I1 est demontre que les interactions vibroniques fournissent une stabilisation thermodynamique suppltmentaire. Des calculs ont cte faits pour VCI, et VBr, avec des Ctats fondamentaux doublement dCgtnerCs. Pour ces molecules-ci il est dtmontre que I'effet est petit.Eine Methode wird eingefuhrt, die die Herleitung der Gleichungen fur die Berechnung von statistischen Summen fur vibronische Systeme vereinfacht. Im Rahmen der Naherung der "unabhangigen Anordnungen" sind analytische Ausdrucke der thermodynamischen Funktionen fur Molekule mit entarteten Grundzustanden (Entartung von Typ E -6 und E -e ) gefunden worden. E s wird gezeigt, dass vibronische Wechselwirkungen eine zusatzliche thermodynamische Stabilisierung geben. Berechnungen sind fur VC1, und VBr4 mit doppelt entarteten Grundzustanden ausgefuhrt worden. Fur diese Molekule ist der Effekt klein.

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“…The vanadium tetrachloride molecule has one unpaired electron and is a liquid at room temperature with enough vapor pressure to make it a candidate for gas-phase experiments bearing on the Jahn–Teller (JT) effect (JTE), but many experiments were done in the liquid and in solution as well. The electronic absorption spectrum, − vibrational spectrum, − photoelectron spectrum (PES), − magnetic deflection spectrum, electron paramagnetic resonance (EPR) spectrum, − nuclear magnetic resonance spectrum, electric deflection, electric dipole moment, electron diffraction, − and magnetic susceptibility ,,,, have all been studied, sometimes with respect to the JTE, sometimes not.…”

Section: Introduction and Reviewmentioning

confidence: 99%

Jahn–Teller Effect in VCl₄

et al. 2013

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A theoretical study is made of the Jahn-Teller and other properties of vanadium tetrachloride. Relativistic effective core potentials and corresponding valence spin-orbit operators are used with Gaussian atomic orbitals to compute self-consistent-field and spin-orbit configuration-interaction wave functions. Energy-surface parameters, electronic excitation energies, vibronic energy levels, and g factors are computed. Electron correlation is shown to have a substantial effect on the Jahn-Teller properties. As have others, we find the Jahn-Teller effect in VCl4 to be of the dynamic form.

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Selection rules and Raman spectrum of a molecule with a degenerate ground state and zero spin-orbit coupling: VCl4

Cited by 11 publications

References 15 publications

Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Thermodynamic functions for vibronic systems

Jahn–Teller Effect in VCl₄

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Selection rules and Raman spectrum of a molecule with a degenerate ground state and zero spin-orbit coupling: VCl4

Cited by 11 publications

References 15 publications

Absorption and Luminescence Spectroscopy of MnO42--Doped Crystals of BaSO4

Absorption and Luminescence Spectroscopy of MnO42--Doped Crystals of BaSO4

Thermodynamic functions for vibronic systems

Jahn–Teller Effect in VCl4

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Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Absorption and Luminescence Spectroscopy of MnO₄²^--Doped Crystals of BaSO₄

Jahn–Teller Effect in VCl₄