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High-levelab initiocalculations have been performed on the PBr radical by using multi-reference configuration interaction method plus Davidson correction (+Q) with correlation-consistent quadruple-ζ quality basis set. The potential energy curves (PECs) of the 22 Λ–S states of PBr have been obtained, most of which are reported for the first time. From the PECs of the bound states, the spectroscopic constants have been determined, in good agreement with the experimental results where available. Due to the large state density, there exhibits complicated interactions in the electronic excited states of PBr. The possible interactions by the spin–orbit coupling (SOC) effect have been discussed based on the evaluatedR-dependent spin–orbit matrix elements. The 51 Ω states, generating from the 22 Λ–S states after taking SOC into account, have been computed. The Λ–S component analysis of the wavefunctions for the Ω states indicates the strong interaction of the Λ–S states especially at the avoided crossing points and near the dissociation limits. Finally, the transition dipole moments of several transitions arising from upper Ω states to the X10+and X21 states and the corresponding radiative lifetimes have been studied. Our calculation results provide new information that should be valuable for further experimental studies on the electronic excited states of the PBr radical. [ABSTRACT FROM AUTHOR]

High-level calculations using internally contracted multireference configuration interaction including Davidson correction (icMRCI+Q) method have been carried out for the ground singlet states, the first excited states, and the lowest triplet states of a series of fluorine-substituted carbenes FCX (X = H, F, Cl, Br, and I). Equilibrium geometries and vibrational frequencies of the three electronic states, adiabatic transition energy of the first excited singlet state, as well as the ground singlet-lowest triplet energy gap (S-T gap) of each of FCX carbenes have been obtained. Effects of the basis set of icMRCI+Q calculation on the geometries and energies have been investigated. In addition, various corrections, including the scalar relativistic effect, spin-orbit coupling, and core-valence correlation, have been studied in calculating the transition energies and the S-T gaps, especially for heavy-atom carbenes. This results have been compared with previous calculations using a variety of methods. Our icMRCI+Q results are in very good agreement with the high-resolution laser-based spectroscopic results where available. Some structure and spectroscopic constants of the fluorine-substituted carbenes which are void in the literature have been provided with consistent high-level calculations. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Total 34 Λ-S states of the PCl molecule have been studied by using the multi-reference configuration interaction plus the Davidson correction (MRCI+Q) method with the correlation consistent quadruple-zeta quality basis set. These states are correlated to three dissociation limits P( 4 S u )+Cl( 2 P u ), P( 2 D u )+Cl( 2 P u ), and P( 2 P u )+Cl( 2 P u ), respectively. The potential energy curves (PECs) of the Λ-S states have been calculated, from which the spectroscopic constants of the bound states are determined. The calculated spectroscopic results well reproduce the available measurements. The spin–orbit matrix elements between the Λ-S states have been calculated, which indicate that the perturbations exist in the interacting system 1 1 Π−2 3 Π and 1 1 Π−2 3 Σ − . And the excited a 1 Δ, b 1 Σ + , 2 1 Σ + states could be predissociated induced by the spin–orbit coupling (SOC) effect. The SOC calculation on the PCl molecule has been performed with the state interaction method. This is the first time that the SOC effect of the PCl has been studied theoretically. The SOC effect leads to the 34 Λ-S states split into the 74 Ω states. The ground state X 3 Σ − splits into the X 3 Σ 0 − + (X 1 0 + ) and X 3 Σ 1 − (X 2 1) states. For the zero-field splitting of the X 3 Σ − state, the spin–orbit contribution of 6 cm −1 is much larger than spin-spin contribution of 0.32 cm −1 . Under the influence of the SOC effect, the spectroscopic results of the a 1 Δ and b 1 Σ + states have very small changes, but the dissociation energies strongly decrease. The transition properties of PCl are also predicted, including the E 1, M 1, and E 2 transition moments, the Franck–Condon factors, the transition probabilities, and the radiative lifetimes. For the transitions from a 1 Δ-X 3 Σ − and b 1 Σ + −X 3 Σ − , the transition probabilities are in order of A E 1 > A M 1 ≫ A E 2 . The lifetimes for the b 1 Σ + ( v׳ =0) state are 4.87ms ( E 1) and 4.57 ms ( E 1+ M 1), in good agreement with the available experimental result of 4.9±0.8 ms. [ABSTRACT FROM AUTHOR]

We report the experimental evidence of the one-photon resonance in the cationic excited state of cyclopentanone using the femtosecond time-resolved pump-probe method. The transients of the parent ion and the C 2 H 4 + fragment exhibit constant depletion in the pump-probe delay time up to 7 ps, however, that of the C 4 H 8 + /C 3 H 4 O + fragment presents formation behavior. By recording dependence of the ion yields as the probe laser intensity, we demonstrate one 400-nm photon resonance in the cationic excited state, which is assigned as the D 4 ( 2 A) cationic state based on the theoretical calculations. Possible dissociation mechanism of the D 4 state is also discussed. [ABSTRACT FROM AUTHOR]

High-level ab initio calculations on the ground and the excited states of the SrH molecule have been carried out utilizing the multi-reference configuration interaction method plus Davidson correction (MRCI+Q) method, with small-core relativistic effective core potentials together with the corresponding correlation consistent polarized valence basis sets. The potential energy curves (PECs) of the 16 Λ–S states have been obtained with the aid of the avoided crossing rule between electronic states of the same symmetry. The spectroscopic constants of the bound states were calculated, most of which have been reported for the first time, with those pertaining to the X 2 Σ + , A 2 П, B 2 Σ + , and A′ 2 Δ states being in line with the available experimental and theoretical values. The calculated spin–orbit matrix element indicates a strong interaction between the X 2 Σ + and A 2 П states in the Franck–Condon region. The spin–orbit coupling (SOC) splits the lowest strongly bound X 2 Σ + , A 2 П, A′ 2 Δ, B 2 Σ + , and D 2 Σ + states into 9 Ω states. For the D 2 Σ + state, the SOC shifts the potential-well minimum to higher energy and shortens the bond length. The transition properties of the bound Λ–S states were predicated, including the transition dipole moments (TDMs), the Franck–Condon factors, and the radiative lifetimes. The lifetimes were calculated to be 34.2 ns ( v ′=0) and 55.0 ns ( v ′=0) for A 2 П and B 2 Σ + , in good agreement with the experimental results of 33.8±1.9 ns and 48.4±2.0 ns. [ABSTRACT FROM AUTHOR]

The potential energy curves (PECs) of the 22 Λ–S states of the phosphorus monoiodide (PI) molecule have been calculated at the level of MRCI+Q method with correlation-consistent quadruple-ζ quality basis set. The spectroscopic constants of the bound states are determined, which well reproduce the available measurements. The metastable a 1 Δ state has been reported for the first time, which lies between the X 3 Σ − and b 1 Σ + states and have much deeper well than the ground state. The R -dependent spin–orbit (SO) matrix elements are calculated with the full-electron Breit–Pauli operator. Based on the SO matrix elements, the perturbations that the 2 3 Π state may suffer from are analyzed in detail. The SOC effect makes the original Λ–S states split into 51 Ω states. In the zero-field splitting of the ground state X 3 Σ − , the spin–spin coupling contribution (2.23 cm −1 ) is found to be much smaller compared to the spin–orbit coupling contribution (50 cm −1 ). The avoided crossings between the Ω states lead to much shallower potential wells and the change of dissociation relationships of the states. The Ω-state wavefunctions are analyzed depending on their Λ–S compositions, showing the strong interactions among several quasidegenerate Λ–S states of the same total SO symmetry. The transition properties including electric dipole ( E 1), magnetic dipole ( M 1), and electric quadrupole ( E 2) transition moments ( TM s), the Franck–Condon factors, the transition probabilities and the radiative lifetimes are computed for the transitions between Ω components of a 1 Δ and b 1 Σ + states and ground state. The transition probabilities induced by the E 1, E 2, and M 1 transitions are evaluated. The E 2 makes little effect on transition probabilities. In contrast, the E 1 transition makes the main contribution to the transition probability and the M 1 transition also brings the influence that cannot be neglected. Finally, the radiative lifetimes are determined with the transition moments including E 1 and M 1. The lifetime of transition (2)0 + –X 1 0 + is evaluated at the level of millisecond, much smaller than that of the transition (2)0 + –X 2 1. [ABSTRACT FROM AUTHOR]

Highlights: [•] The excited states of GeH+ were calculated with MRCI+Q method. [•] The spin–orbit coupling effect was taken into account in the calculations. [•] Spectroscopic constants of bound Λ-S and Ω states of GeH+ were computed. [•] The radiative lifetimes of A1Π1, a3Π0+, and a3Π1 states of GeH+ were obtained. [ABSTRACT FROM AUTHOR]

• Accurate electronic state properties of TlF are calculated with MRCI + Q method. • Spectroscopic constants for bound states of TlF are obtained. • The radiative lifetimes of the transitions a3Π 0+ -X1Σ+ 0+ and a3Π 1 -X1Σ+ 0+ are computed. The low-lying electronic states of thallium fluoride (TlF) are investigated using the multi-reference configuration interaction method including the core-valence and the spin-orbit coupling effects. Based on the calculated potential energy curves, the spectroscopic constants of the bound states of TlF are determined, which are in accordance with available theoretical and experimental results in the literature. The transition dipole moments, Franck-Condon factors, and the radiative lifetimes of the a3Π 0+ - X1Σ+ 0+ and a3Π 1 - X1Σ+ 0+ transitions have been reported. Our study is expected to be helpful for understanding the spectroscopy and dynamics of electronic excited states of the TlF molecule. [ABSTRACT FROM AUTHOR]