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Quasi-2D Ruddlesden-Popper perovskites attract great attention as an optical gain media in lasing applications due to their excellent optoelectronic properties. Herein, a novel quasi-2D Ruddlesden-Popper perovskite based on 2-thiophenemethylammonium (ThMA) is synthesized by a facile solution-processed method. In addition, an anti-solvent treatment method is proposed to tune the phase distribution, and preferential orientation of quasi-2D (ThMA)2Cs n -1Pb n Br3n+1 thin films. The large-n-dominated narrow domain distribution improves the energy transfer efficiency from small-n to large-n phases. Also, the highly oriented nanocrystals facilitate the efficient Förster energy transfer, beneficial for the carrier population transfer. Furthermore, a green amplified spontaneous emission with a low threshold of 13.92 µJ/cm2 is obtained and a single-mode vertical-cavity laser with an 0.4 nm linewidth emission is fabricated. These findings provide insights into the design of the domain distribution to realize low-threshold multicolor continuous-wave or electrically driven quasi-2D perovskites laser.

We propose a physical scheme to study the formation of optical soliton molecules (SMs), consisting of two solitons bound together with a π-phase difference, and the scattering of SMs by a localized parity-time (PT)-symmetric potential. In order to stabilize SMs, we apply an additional space-dependent magnetic field to introduce a harmonic trapping potential for the two solitons and balance the repulse interaction induced by the π-phase difference between them. On the other hand, a localized complex optical potential obeying PT symmetry can be created through an incoherent pumping and spatial modulation of the control laser field. We investigate the scattering of optical SMs by the localized PT-symmetric potential, which exhibits evident asymmetric behavior and can be actively controlled by changing the incident velocity of SMs. Moreover, the PT symmetry of the localized potential, together with the interaction between two solitons of the SM, can also have a significant effect on the SM scattering behavior. The results presented here may be useful for understanding the unique properties of SMs and have potential applications in optical information processing and transmission.

We propose a scheme to realize parity-time-symmetric flatband systems by introducing on-site gain/loss to rhombic lattices with staggered couplings. Such non-Hermitian lattices possess chiral-symmetry-protected third-order exceptional points, exhibiting an ∼є1/3 eigenvalue separation.

We elucidate the itinerant ferromagnetism of a dipolar Fermi gas with a Raman-induced spin-orbit coupling by investigating the exotic phase diagrams at zero and finite temperature. It is revealed that the dipolar interaction along with spin-orbit coupling can corroborate the formation of ferromagnetism and the Raman coupling adversely eliminates the tendency to this ferromagnetism transition, which greatly transcends the general understanding of this subject with contact interaction only. We explore the ground states through the density and spin-flip distribution in momentum space, which exhibits novel degeneracy at strong Raman coupling indicated by a non-zero entropy at zero temperature. We calculate the transition temperatures well within the reach of an experimental system when altering the dipolar and spin-orbit coupling strength, which paves a way to the further experimental realization., 6 pages,5 figures

Higher-order exceptional points (EPs), which appear as multifold degeneracies in the spectra of non-Hermitian systems, are garnering extensive attention in various multidisciplinary fields. However, constructing higher-order EPs still remains a challenge due to the strict requirement of the system symmetries. Here we demonstrate that higher-order EPs can be judiciously fabricated in parity–time ( PT )-symmetric staggered rhombic lattices by introducing not only on-site gain/loss but also non-Hermitian couplings. Zero-energy flatbands persist and symmetry-protected third-order EPs (EP3s) arise in these systems owing to the non-Hermitian chiral/sublattice symmetry, but distinct phase transitions and propagation dynamics occur. Specifically, the EP3 arises at the Brillouin zone (BZ) boundary in the presence of on-site gain/loss. The single-site excitations display an exponential power increase in the PT -broken phase. Meanwhile, a nearly flatband sustains when a small lattice perturbation is applied. For the lattices with non-Hermitian couplings, however, the EP3 appears at the BZ center. Quite remarkably, our analysis unveils a dynamical delocalization-localization transition for the excitation of the dispersive bands and a quartic power increase beyond the EP3. Our scheme provides a new platform toward the investigation of the higher-order EPs and can be further extended to the study of topological phase transitions or nonlinear processes associated with higher-order EPs.

Two-dimensional transition metal dichalcogenides with outstanding properties open up a new way to develop optoelectronic devices such as phototransistors and light-emitting diodes. Heterostructure with light-harvesting materials can produce many photogenerated carriers via charge and/or energy transfer. In this paper, the ultrafast dynamics of charge transfer in zero-dimensional CsPbBr3 quantum dot/two-dimensional MoS2 van der Waals heterostructures are investigated through femtosecond time-resolved transient absorption spectroscopy. Hole and electron transfers in the ps and fs magnitude at the interfaces between MoS2 and CsPbBr3 are observed by modulating pump wavelengths of the pump-probe configurations. Our study highlights the opportunities for realizing the exciton devices based on quantum dot/two-dimensional semiconductor heterostructures.

The potential energy curves were calculated for the X3Σ−, A′3∆, A′′3Σ+, A3Π, B3Σ−, and C3Π states of the sulfur monoxide radical. The transition dipole moments between these states were computed. No dipole-allowed electronic emissions originate from the X3Σ−, A′3∆, and A′′3Σ+ states for the sake of symmetry and spin limitation. The rotationless radiative lifetimes of all vibrational levels are in the order of 10−5–10−6 s for the A3Π state, 10−7–10−8 s for the B3Σ− state, and 10−6 s for the C3Π state. The lifetimes of all vibrational levels indicate that the spontaneous emissions originating from the A3Π, B3Σ−, and C3Π states easily occur. Overall, the emissions from the A3Π–X3Σ−, B3Σ−–X3Σ−, C3Π–X3Σ−, A3Π –A′′3Σ+, C3Π–A3Π, and C3Π–A′′3Σ+ systems are strong, whereas the emissions from the B3Σ−–A3Π, C3Π–A′3∆ and C3Π–B3Σ− systems are so weak that they are very difficult to be measured in a spectroscopy experiment. The distribution of the spectral intensity is evaluated for spontaneous emissions of each system. The spontaneous emissions of the B3Σ−–X3Σ− system are so strong that they may potentially be measured in outer space, although the intense emissions of this system are in the visible and near-UV regions.

In this work, we report the potential energy curves for the X2Π, A2Σ+, B2Σ+, G2Δ, G′2Σ-, C2Π, and D2Σ+ states of the AlO radical and the transition dipole moments between these states. The calculations are performed with the complete active space self–consistent field method, followed by the valence internally contracted multireference configuration interaction approach under the framework of the Born–Oppenheimer approximation. We find that the rotationless radiative lifetimes are in the order of several hundred ns for the B2Σ+ state, several tens of ns for the C2Π state, and several to more than ten ns for the first well of the D2Σ+ state. These lifetimes indicate that the transitions originated from these states easily occur. The rotationless radiative lifetimes are several to several hundred µs for the G2Δ and G′2Σ- states, and in the order of 10 to 100 µs for the A2Σ+ state. The Einstein coefficients of emissions from the B2Σ+–X2Σ+, C2Π–X2Σ+, and C2Π–A2Π systems, as well as from the first well of the D2Σ+ state to the X2Σ+ and A2Π states are very large, suggesting that the transitions from these systems should be able to be measured readily via spectroscopy. The rovibrational constants are first obtained from the analytic potential by numerically solving the rovibrational Schrodinger equation, and then the spectroscopic parameters are evaluated by fitting the vibrational levels. The distributions of the intensity and wavelength of the spectral transitions are new. The radiative lifetimes reported in this work are also new for all vibrational levels of the C2Π, G2Δ and G′2Σ- states, as well as for υ ≥ 1 levels of the C2Π state. The results reported in this study can be used to detect the 26Al16O radical in outer space.

The potential energy curves of 23 states of AlN radical are calculated to accurately determine the first several lowest-lying singlet and triplet states. The calculations are done using the CASSCF method, which is followed by the valence internally contracted MRCI approach. The rotationless radiative lifetimes of the vibrational levels are approximately 10−7–10−8 s for the C3Π, D3Π, and E3Δ states, 101–10−4 s for the A3Σ− state, and 10−4–10−5 s for the B3Σ+ state. The origins of the vibronic bands and the radiative lifetimes agree well with the available experimental and other theoretical results. The Einstein coefficients of many vibronic emissions are large for the C3Π–X3Π, C3Π–A3Σ−, D3Π–X3Π, D3Π–A3Σ−, and E3Δ–X3Π transitions and therefore, these transitions are strong. The emissions of the E3Δ–D3Π system are so weak that it is difficult to measure them through spectroscopy. The spectral distribution of the vibronic emissions is evaluated for the transitions of 12 pairs of states. In terms of the radiative lifetimes and transition probabilities obtained here, several spectroscopic routines for observing these states via spectroscopy are proposed.

In this study, the potential energy curves are calculated for the a1Σ+, b1Π, c1Δ, d1Σ+, e1Π, f1Δ, and g1Σ− states of the AlN radical. The transition dipole moments between them are computed. The rotationless radiative lifetimes of the vibrational levels are found to be approximately several µs for the d1Σ+ and g1Σ− states, on the order of several hundred ns for the e1Π state, and one-tenth to several µs for the deep well of the f1Δ state. These results suggest that the spontaneous emissions originated from these states occur readily. The rotationless radiative lifetimes of the vibrational levels are on the order of 10–100 µs for the c1Δ state, 1000 µs for the vdW minimum of the f1Δ state, and 10–1000 µs for the b1Π state. In addition, the rotationless radiative lifetimes of these states decrease with the increasing vibrational level. This result suggests that the spontaneous emissions generated from these states at lower levels should be difficult to occur. The Einstein coefficients of spontaneous emissions from the d1Σ+–a1Σ+, d1Σ+–b1Π, e1Π–a1Σ+, e1Π–b1Π, and g1Σ−–b1Π systems, as well as from the f1Δ state to the b1Π and c1Δ states are large, indicating that the emissions of these systems can be measured readily via spectroscopy. The Einstein coefficients of the e1Π–d1Σ+ transition are very small and the emissions originating from the vdW minimum of the f1Δ state are very weak, predicting that these transitions are very difficult to be detected in spectroscopy experiments.

This study calculates the potential energy curves of 12 Λ-S and 27 Ω states, which belong to the first dissociation channel of SiC+ cation. The potential energy curves are computed with the complete active space self–consistent field method, which is followed by the valence internally multireference configuration interaction approach with the Davidson correction. The transition dipole moments are determined. Core-valence correlation and scalar relativistic correction, as well as extrapolation of the potential energies to the complete basis set limit are included. The spin-orbit coupling effect on the spectroscopic parameters and vibrational properties is evaluated. The vibrational band origins, Franck–Condon factors, and Einstein coefficients of spontaneous emissions are calculated. The rotationless radiative lifetimes of the vibrational levels are approximately 10−5 s long for the e2Π state. The partial radiative lifetimes of vibrational levels are approximately 10−7 s long for the 24Π and 24Σ− states, 10−5 to 10−6 s long for the 22Σ− state and the first well of the 14Π state, and very short for the second well of the 14Π state. Overall, the emissions are strong for the 22Σ−–c2Σ−, 24Σ−–X4Σ−, 24Π–X4Σ− transitions, and for the second well of the 14Π–14Σ+ transition. The spectral range of emissions is determined. In terms of the radiative lifetimes and transition probabilities obtained in this paper, some guidelines for detecting these states are proposed via spectroscopy. These results can be used to measure the emissions from the SiC+ cation, in particular, in interstellar clouds.

This paper calculates the potential energy curves of 21 Λ–S and 42 Ω states, which arise from the first two dissociation asymptotes of the CO+ cation. The calculations are conducted using the complete active space self–consistent field method, which is followed by the valence internally contracted multireference configuration interaction approach with the Davidson correction. To improve the reliability and accuracy of the potential energy curves, core–valence correlation and scalar relativistic corrections, as well as the extrapolation of potential energies to the complete basis set limit are taken into account. The spectroscopic parameters and vibrational levels are determined. The spin–orbit coupling effect on the spectroscopic parameters and vibrational levels is evaluated. To better study the transition probabilities, the transition dipole moments are computed. The Franck–Condon factors and Einstein coefficients of some emissions are calculated. The radiative lifetimes are determined for a number of vibrational levels of several states. The transitions between different Λ–S states are evaluated. Spectroscopic routines for observing these states are proposed. The spectroscopic parameters, vibrational levels, transition dipole moments, and transition probabilities reported in this paper can be considered to be very reliable and can be used as guidelines for detecting these states in an appropriate spectroscopy experiment, especially for the states that were very difficult to observe or were not detected in previous experiments.

In this work, we calculate the potential energy curves of 16 Λ-S and 36 Ω states of beryllium boride (BeB) radical using the complete active space self-consistent field method, followed by the valence internally contracted multireference configuration interaction approach with Davidson correction. The 16 Λ-S states are the X2Π, A2Σ+, B2Π, C2Δ, D2Ʃ−, E2Σ+, G2Π, I2Σ+, a4Σ−, b4Π, c4Σ−, d4Δ, e4Σ+, g4Π, h4Π, and 24Σ+, which are obtained from the first three dissociation channels of the BeB radical. The Ω states are obtained from the Λ-S states. Of the Λ-S states, the G2Π, I2Σ+, and h4Π states exhibit double well curves. The G2Π, b4Π, and g4Π states are inverted with the spin-orbit coupling effect included. The d4Δ, e4Σ+, and g4Π states as well as the second well of the h4Π state are very weakly bound. Avoided crossings exist between the G2Π and H2Π states, the A2Σ+ and E2Σ+ states, the c4Σ− and f4Σ− states, the g4Π and h4Π states, the I2Σ+ and 42Σ+ states, as well as the 24Σ+ and 34Σ+ states. To improve the quality of the potential energy curves, core-valence correlation and scalar relativistic corrections, as well as the extrapolation of the potential energies to the complete basis set limit, are included. The transition dipole moments are computed. Spectroscopic parameters and vibrational levels are determined along with Franck–Condon factors, Einstein coefficients, and radiative lifetimes of many electronic transitions. The transition probabilities are evaluated. The spin-orbit coupling effect on the spectroscopic parameters and vibrational levels is discussed. The spectroscopic parameters, vibrational levels, and transition probabilities reported in this paper can be considered very reliable and can be employed to predict these states in an appropriate spectroscopy experiment.

This work calculates the potential energy curves of 9 Λ-S and 28 Ω states of the NCl+ cation. The technique employed is the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson correction. The Λ-S states are X2Π, 12Σ+, 14Π, 14Σ+, 14Σ−, 24Π, 14Δ, 16Σ+, and 16Π, which are yielded from the first two dissociation channels of NCl+ cation. The Ω states are generated from these Λ-S states. The 14Π, 14Δ, 16Σ+, and 16Π states are inverted with the spin-orbit coupling effect included. The 14Σ+, 16Σ+, and 16Π states are very weakly bound, whose well depths are only several-hundred cm− 1. One avoided crossing of PECs occurs between the 12Σ+ and 22Σ+ states. To improve the quality of potential energy curves, core-valence correlation and scalar relativistic corrections are included. The potential energies are extrapolated to the complete basis set limit. The spectroscopic parameters and vibrational levels are calculated. The transition dipole moments are computed. The Franck-Condon factors, Einstein coefficients, and radiative lifetimes of many transitions are determined. The spectroscopic approaches are proposed for observing these states according to the transition probabilities. The spin-orbit coupling effect on the spectroscopic and vibrational properties is evaluated. The spectroscopic parameters, vibrational levels, transition dipole moments, as well as transition probabilities reported in this paper could be considered to be very reliable.

Ab initio calculations have been performed to study the transition properties of the PS+ cation. Transition dipole moments of fourteen dipole-allowed transitions, between the X1Σ+, A1Σ−, B1Δ, C1Π, D1Σ+, E1Π, and F1Σ+ states, have been calculated with the aug-cc-pV6Z basis set. Transition probabilities, band origins, as well as radiative lifetimes of vibronic emissions are predicted. The vibrational radiative lifetimes are estimated to be in order of 10−8 s for the D1Σ+, F1Σ+, and first well of E1Π states; 10−7 s for the C1Π state; 10−3-10−4 s for the second well of E1Π state. Various curve crossings and avoided crossings are revealed with the help of our computed spin–orbit coupling matrix elements. The intricate couplings among different electronic states are analyzed. We propose that the curve crossing with the D1Σ+ state may be responsible for the fact that the C1Π ν' > 7 vibrational levels cannot be detected in experiment.

This work studied the variation in spectral emissivity with growth of oxide layer at the different temperatures. For this reason, we measured the normal spectral emissivity during the growth of oxide layer on the sample surface at a wavelength of 1.5 μm over a temperature range 800–1100 K. In the experiment, the temperature was measured by the two thermocouples, which were symmetrically welded onto the front surface of specimens. The average of their readings was regarded as the true temperature. The detector should be perpendicular to the specimen surface as accurately as possible. The variation in spectral emissivity with growth of oxide layer was evaluated at a certain temperature. Altogether 11 emissivity models were evaluated. The conclusion was gained that the more the number of parameters used in the models was, the better the fitting accuracy became. On the whole, all the PEE models, the four-parameter LEE model and the five-parameter PFE, PLE and LEE models could be employed to well fit this kind of variation. The variation in spectral emissivity with temperature was determined at a certain thickness of oxide film. Almost all the models studied in this paper could be used to accurately evaluate this variation. The approximate models of spectral emissivity as a function of temperature and oxide-layer thickness were proposed. The strong oscillations of spectral emissivity were observed, which were affirmed to arise from the interference effect between the two radiations stemming from the oxide layer and from the substrate. The uncertainties in the temperature of steel 430 generated only by the surface oxidization were approximately 4.1–10.7 K in this experiment.

We investigate band evolution of chiral and non-chiral symmetric flatband photonic rhombic lattices by applying a strain along the diagonal direction, and thereby demonstrating Landau-Zener Bloch (LZB) oscillations in the presence of a refractive index gradient. The chiral and non-chiral symmetric rhombic lattices are obtained by adding a detuning to uniform lattices. For the chiral symmetric lattices, the middle flatband is perturbed due to the chiral symmetry breaking while a nearly flatband appears as the bottom band with the increase of strain-induced next-nearest-neighbor hopping. Consequently, LZB oscillations exhibit intriguing characteristics such as asymmetric energy transitions and almost complete suppression of the oscillations. Nevertheless, for the non-chiral symmetric lattices, flatband persists owing to the retained particle-hole symmetry and evolves into the bottom band. Remarkably, the band gap can be readily tuned, which allows controlling of the amplitude of Landau-Zener tunneling (LZT) rate and may lead to thorough LZT. Our analysis provides an alternative perspective on the generation of tunable flatband and may also bring insight to study the symmetry and topological characterization of the flatband.

Properties of the transitions between Ω states originating from the X3Σ–, A3Π, a1Δ, b1Σ+, and c1Π states of NH were investigated herein. The radiative lifetimes of the A3Π state were 0.42, 0.43, 0.44, 0.50, 0.58, 0.70, 0.90, and 1.45 μs for the υ = 0 – 7 levels; and those of the c1Π state were 0.44, 0.54, and 0.72 μs for υ = 0 – 2, respectively. The radiative lifetimes of the A3Π2 state were 0.48, 0.53, 0.60, 0.68, 0.79, 0.95, 1.21, and 1.95 μs for υ = 0 – 2, respectively, which are slightly larger than those of the A3Π state for same υ. The radiative lifetimes of the A3Π2 state were almost the same as those of the A3Π0+ and A3Π0– states. The radiative lifetimes of the A3Π2, A3Π0+, and A3Π0– states were slightly larger than those of the A3Π1 state. The radiative lifetimes of the first 16 levels of the a1Δ2 state varied from 2.4 to 432.8 s. Those of the b1Σ+0+ state were between 0.3 and 72 ms. Those of the c1Π1 state were determined as approximately 0.44, 0.54, and 0.72 μs for υ = 0 – 2, respectively. The radiative lifetimes calculated herein compared well with the available experimental results. The Franck–Condon factors and Einstein A coefficients of all possible transitions were calculated. The results reported herein provide useful guidelines for future investigations, both experimental and theoretical.

Detecting aluminum silicon can yield useful information concerning the depletion of silicon and aluminum and their recycling in astrophysical sources. In addition, such detection can be helpful for understanding gas–phase aluminum and silicon chemistry in the interstellar/circumstellar atmosphere. However, only a few transition properties of this radical have been reported. Therefore, the potential energy curves of several lowest–lying doublet states and the transition dipole moments between them were calculated using the icMRCI approach. Core–valence correlation correction, scalar relativistic correction, and spin–orbit coupling effect were included to improve the accuracy of transition properties. The radiative lifetimes of the first 16 levels were approximately 4.8 – 679.5 ms for the c2Π1/2 state, 2.2 – 431 ms for the c2Π3/2 state, 29.3 – 40.4 µs for the d2Π1/2 state, 21.2 – 30.1 µs for the d2Π3/2 state, and 88.7 – 175.6 µs for the e2Σ+1/2 state. The spontaneous emissions from the c2Π1/2 and c2Π3/2 states to the a2Σ–1/2, b2Δ3/2, and b2Δ5/2 states and those from the e2Σ+1/2 state to the d2Π1/2 and d2Π3/2 states were located in the radio–frequency region. The d2Π1/2 – a2Σ–1/2 and d2Π3/2 – a2Σ–1/2 transitions were the strongest, followed by d2Π1/2 – b2Δ3/2, d2Π3/2 – b2Δ3/2, d2Π3/2 – b2Δ5/2, d2Π1/2 – c2Π1/2, d2Π3/2 – c2Π3/2, e2Σ+1/2 – c2Π1/2, and e2Σ+1/2 – c2Π3/2 transitions. The spontaneous emissions from these systems were located in the infrared region. The variation in the radiative lifetime of a level υ versus the rotational quantum number J was investigated for the d2Π1/2, d2Π3/2, and e2Σ+1/2 states.

The transition properties were calculated for the X2Σ+, A2Π, B2Σ+, C2Π, and a4Σ+ states, and eight Ω states of BO. The calculations were performed using the CASSCF method, followed by the icMRCI approach. Core–valence correlation and relativistic corrections were included. The radiative lifetimes of the first 16 vibrational levels were roughly 1.5–1.6 μs for the A2Π state, 96–177 ns for the B2Σ+ state, and 16.7–18.5 ns for the C2Π state. The B2Σ+ – X2Σ+ and C2Π – X2Σ+ transitions were strong, followed by the A2Π – X2Σ+, B2Σ+ – A2Π, and C2Π – A2Π transitions. The radiative lifetime of the first 16 levels was approximately 4.9–10.4 ms for the a4Σ+1/2 state, 0.21–24 ms for the a4Σ+3/2 state, 2.9–3.6 μs for the A2Π1/2 state, 3.5–3.8 μs for the A2Π3/2 state, 134–230 ns for the B2Σ+1/2 state, 23.2–25.4 ns for the C2Π1/2 state, and 23.0–25.2 ns for the C2Π3/2 state. Among all spin–forbidden transitions generated from the a4Σ+ state, the a4Σ+1/2 – X2Σ+1/2 and a4Σ+3/2 – X2Σ+1/2 transitions were relatively strong. The transition properties reported herein were compared with the experimental results. The variation of the radiative–lifetime distribution with the rotational angular quantum number was evaluated for A2Π1/2, A2Π3/2, B2Σ+1/2, C2Π1/2, and C2Π3/2 states. It is expected that the transition properties calculated in this study can provide some useful guidelines for future experimental and theoretical investigations.

The potential energy curves of X 2Π, A 2Σ+, B 2Π, C 2Σ+, a 4Π, b 4Σ+, c 4Δ, and d 4Σ– states of SiP molecules and the transition dipole moments of the transitions between these states were calculated using the CASSCF method, followed by the icMRCI approach. The radiative lifetimes of the first 16 vibrational levels were 0.27 – 66 and 1.5 – 2.38 × 104 ms for the A 2Σ+ and b 4Σ+ states, respectively. Those were 146 – 497, 93 – 254, 23.9 – 30.3, and 0.85 – 1.1 µs for the B 2Π, c 4Δ, d 4Σ–, and C 2Σ+ states, rspectively. The spin–orbit coupling constants of the X 2Π, B 2Π, a 4Π, and b 4Σ+ states were evaluated. Including the spin–orbit coupling effect, the radiative lifetimes of the A 2Σ+1/2, B 2П1/2, B 2П3/2, C 2Σ+1/2, a 4П–1/2, a 4П1/2, a 4П3/2, a 4П5/2, b 4Σ+1/2, and b 4Σ+3/2 states were calculated. The lifetimes of the first 16 levels were 0.35 – 0.42, 3.1 – 5.5, 1.3 – 5.8, and 30 – 57 s for the a 4П–1/2, a 4П1/2, a 4П3/2, and a 4П5/2 states, respectively. And those were 2.3 – 268 and 2.6 – 257 ms for the b 4Σ+1/2 and b 4Σ+3/2 states, respectively. The SOC effect made the radiative lifetimes of the A 2Σ+, B 2Π, and C 2Σ+ states become longer. Among the spontaneous emissions between these Ω states, those from the C 2Σ+1/2 state to the X 2П3/2, X 2П1/2, and A 2Σ+1/2 states were the strongest. The results indicated that the strong emissions originated from the lower levels of the C 2Σ+1/2 state. Furthermore, almost all of these strong emissions were in the visible region. All emissions generating from the a 4П–1/2, a 4П1/2, a 4П3/2, and a 4П5/2 states are extremely weak. The radiative–lifetime distribution of each level υ versus the rotational quantum number J was evaluated for several Ω states.

The emissivity models of aluminum 7075 were studied during the growth of oxide layer over the temperature range from 800 to 910 K at a wavelength of 1.5 μm. In the experiment, the samples were heated to a certain temperature and kept at that temperature for approximately 6 h. To determine the accurate emissivity, the surface temperature of specimens was measured by the two thermocouples, which were symmetrically welded onto the front surface of samples. The average of their readings was regarded as the true temperature. Eleven models were employed to evaluate the variation of emissivity with temperature or growth of oxide film on the specimen surface at a certain condition. The effect of the number of parameters used in the models on the fitting quality was studied at a certain temperature. The conclusion was obtained as more the number of parameters used in the models, the better the fitting quality became on the whole. The variation of emissivity with temperature was investigated at a certain thickness of oxide layer. The three approximate models of variation in emissivity with temperature and thickness of oxide film were proposed. The strong oscillations of emissivity were observed during the initial heating period, which were affirmed to arise from the interference effect between the two radiations stemming from the oxide layer and coming from the substrate.

This paper investigates the spectroscopic parameters and transition probabilities of 25 low-lying states, which come from the first five dissociation channels of AlC+ cation. The potential energy curves are calculated with the complete active space self-consistent field method, which is followed by the valence internally contracted multireference configuration interaction approach with Davidson correction. Of these 25 states, only the 35Σ− state is repulsive; the c1Σ+, f1Π, and 15Π states have the double well; the first well of c1Σ+ state and the second well of 15Π state are very weakly bound; the first well of c1Σ+ state has no vibrational levels; the 25Π state and the double well of f1Π state have only several vibrational states; the B3Σ−, E3Σ+, D3Π, 15Σ+, 25Σ−, and 15Π states are inverted when the spin-orbit coupling effect is included. The avoided crossings exist between the B3Σ− and 33Σ− states, the c1Σ+ and d1Σ+ states, the f1Π and 31Π states, the 15Π and 25Π states, as well as the 25Π and 35Π states. Core-valence correlation and scalar relativistic corrections are considered. The extrapolation of potential energies to the complete basis set limit is done. The spectroscopic parameters and vibrational levels are determined for all the Λ–S and Ω bound states. The transition dipole moments are calculated. Franck–Condon factors of a great number of electronic transitions are evaluated. On the whole, the spin-orbit coupling effect on the spectroscopic parameters and vibrational levels is small except for very few states. The results determined in this paper could provide some powerful guidelines to observe these states in a spectroscopy experiment.

This paper calculated the potential energy curves of 21 Λ-S and 42 Ω states of the OF radical. The 21 Λ-S states were the X2Π, A2Σ−, B2Σ−, C2Δ, D2Σ+, E2Σ+, 22Π, a4Σ−, b4Δ, 24Σ−, 14Σ+, 14Π, 24Π, 32Σ+, 32Σ−, 32Π, 42Π, 52Π, 22Δ, 32Δ, and 12Φ, which arose from the first two dissociation limits. The 42 Ω states were generated from these Λ-S states. All the potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI + Q approach. The 14Π, 24Π, 22Π, 42Π, 52Π, 32Σ+, and 32Δ states were repulsive whether the spin-orbit coupling effect included or not, but the A2Σ−, D2Σ+, 32Σ−, 22Δ, and 12Φ states became repulsive with the spin-orbit coupling effect included. Only the 16 Ω states were bound. With the spin-orbit coupling effect accounted for, the X2Π state was inverted among the bound states; the X2Π, a4Σ−, and E2Σ+ states were strongly bound; and the 32Π, b4Δ, B2Σ−, C2Δ, 24Σ−, and 14Σ+ states were very weakly bound. The spectroscopic and vibrational properties were determined. Franck–Condon factors of some transitions were evaluated. The spin-orbit coupling effect on the spectroscopic parameters and vibrational properties was discussed. It is very difficult to explore the X2Π, a4Σ−, and E2Σ+ states by observing the electronic transitions between them because all these strong transitions originating only from the highly-vibrational states of the X2Π or a4Σ− state. It is also very hard to detect the 32Π, b4Δ, B2Σ−, C2Δ, 24Σ−, and 14Σ+ states by observing the transitions originating from these states, because these states are very weakly bound and unstable, though some transitions originating from them are very strong. These results can well explain why the OF radical is very difficult to detect in a spectroscopic experiment by observing the electronic transitions between different states.

The potential energy curves (PECs) of 20 low lying electronic states of SiP + cation are calculated by the internally contracted multi-reference configuration interaction approach. All the 20 low lying electronic states generated by the first two dissociation channels Si + ( 2 P u ) + P( 4 S u ) and Si + ( 2 P u ) + P( 2 D u ). The Davidson correction is taking into account in the calculation. Meanwhile, core-valence correlation and scalar relativistic corrections are included. All the PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated for all the Λ-S bound states, and are compared with the measurements and other theoretical results. The vibrational properties of several weakly-bound states are determined. The Franck–Condon Factors and radiative lifetimes of transitions A 3 Π–X 3 Σ − , b 1 Π–X 3 Σ − and b 1 Π–a 1 Δ are predicted for further study. The transition dipole moments are calculated in this paper.

This work explored the spectroscopic parameters and vibrational properties of 12 states of BrO radical. The 12 states were X 2 Π, A 2 Π, 1 2 Δ, 1 2 Σ + , 1 2 Σ − , 2 2 Σ − , a 4 Σ − , 2 4 Σ − , 1 4 Σ + , 1 4 Δ, 1 4 Π, and 2 4 Π, which were generated from the first dissociation limit, Br( 2 P u ) + O( 3 P g ). The potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI approach with Davidson correction. Of the 12 electronic states, the 2 4 Π state was repulsive. Each state had the single well and only the A 2 Π state had one barrier. The 1 2 Δ, 1 2 Σ + , 1 2 Σ − , 2 2 Σ − , 2 4 Σ − , 1 4 Σ + , 1 4 Δ and 1 4 Π states had only several vibrational levels and were very weakly-bound states, which well depths were less than 110 cm −1 . To improve the quality of potential energy curves, core-valence correlation and scalar relativistic corrections as well as the extrapolation to the complete basis set limit were included. The spectroscopic parameters and vibrational properties were determined. The transition dipole moments between two electronic states and Franck-Condon factors of some transitions were evaluated. The spin-orbit coupling effect on the spectroscopic parameters of the X 2 Π and A 2 Π states was discussed. The spectroscopic parameters and vibrational properties reported in this paper can be expected to be reliably predicted ones.

This work strived to determine the analytical relationships between the spectral emissivity and the wavelength at different temperatures during the growth of oxide layer on the specimen surface of steel 309S. In the experiment, the spectral emissivity was measured at eight wavelengths, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, and 2.1 μm, at temperatures from 800 to 1100 K in increments of 20 K by multispectral radiation thermometry. To accurately measure the normal spectral emissivity, the detector employed in the thermometry should be perpendicular to the surface of specimens as accurately as possible. The temperature of specimen surface was measured by the two thermocouples, which were symmetrically welded onto the front surface of specimens. The average of their readings was regarded as the true temperature. With the spectral emissivity measured here, the variation in the spectral emissivity with wavelength was evaluated at different temperatures and different heating times. Ten emissivity models were evaluated. The effect of number of the parameters used in the models on the fitting accuracy was studied. Both the five-parameter LLWE and LWE models were very suitable for fitting the spectral emissivity and could farthest relieve the effect of heating time on the accuracy of temperature prediction. The uncertainties in the temperature prediction of steel 309S specimens were basically within 10 K by thermometry using the two models over the present temperature and wavelength ranges.

This work studied the potential energy curves of 22 Λ-S states, which were yielded from the first two dissociation limits, P(4Su)+S+(4Su) and P+(3Pg)+S(3Pg), of the PS+ cation. The potential energy curves were calculated employing the CASSCF method, which was followed by the internally contracted MRCI approach with Davidson correction. Core- valence correlation and scalar relativistic corrections as well as basis set extrapolation were included. Of these 22 Λ-S states, only the 35Σ+ state was repluse without the spin-orbit coupling effect, whereas the 35Σ+, 15Δ, 25Σ+, and 15Σ- states were repulse with the spin-orbit coupling effect accounted for. The 21Π and 23Π states had double wells, but the first well of the 23Π state had no vibrational levels and the first well of 21Π state had only one vibrational state. The avoided crossings were found between the 11Π and 21Π states and between the d3Π and 23Π states. The 25Σ+, 15Π, 15Δ, b3Δ, and c3Σ- states were inverted with the spin-orbit coupling effect taken into account. The 15Δ, 25Σ+, 15Σ-, and 21Π states were weakly bound. The spectroscopic properties were evaluated and compared with the experimental and other theoretical results. The Franck-Condon factors of some electronic transitions between different Λ-S states were determined. The vibrational levels of several states were predicted. The spin-orbit coupling effect on the spectroscopic parameters was discussed. Analyses show that the spectroscopic results obtained here can be expected to be reliably predicted ones.

This work explored the spectroscopic parameters and vibrational properties of the 21 Λ–S and 42 Ω states of the AlC radical. The PECs were calculated with the CASSCF method, which was followed by the icMRCI+Q approach. The A4Π, a2Π, 52Π, 22Δ, and 12Φ states as well as the first well of B4Σ− state were inverted with the spin–orbit coupling (SOC) effect included; the 14Δ, 14Σ+, and 22Σ− states as well as the second wells of the B4Σ−, 22Σ+, 32Σ+, 42Π and 52Π states were weakly bound, which well depths were less than 650 cm−1; the B4Σ−, 22Σ+, 32Σ+, 42Π, 52Π, and 22Δ states had double wells and the second wells of these states except for B4Σ− had only several vibrational states; the avoided crossings existed between the 22Σ+ and 32Σ+ states, the 32Σ+ and 42Σ+ states, the B4Σ− and 34Σ− states, the 22Δ and 32Δ states, the 42Π and 52Π states, the 52Π and 62Π states, as well as the 24Π and 34Π states. The extrapolation scheme, core–valence correlation and scalar relativistic corrections were included. The ...

The potential energy curves of X 2Σ+, A 2Π, B 2Σ+, a 4Σ+, and b 4Δ states and their Ω states of CP were calculated using the icMRCI approach. The transition dipole moments between these states were computed. To improve the accuracy of the potential energy curves, core–valence correlation and scalar relativistic corrections were considered. The radiative lifetimes were approximately 10 μs for the A 2Π3/2 and A 2Π1/2 states and 100 ns for the B2Σ+1/2 state; those were approximately 10, 10 – 100, 10, 0.1 – 1, and 10 ms for the a 4Σ+1/2, a 4Σ+3/2, b 4Δ1/2, b 4Δ3/2, and b 4Δ5/2 states, respectively. The spontaneous emissions from the B 2Σ+1/2 – X 2Σ+1/2 system were strong, followed by the A 2Π3/2 – X 2Σ+1/2, A 2Π1/2 – X 2Σ+1/2, B 2Σ+1/2 – A 2Π3/2, and B 2Σ+1/2 – A 2Π1/2 transitions. The strong emissions from the A 2Π3/2 – X 2Σ+1/2 and A 2Π1/2 – X 2Σ+1/2 systems were in the infrared region; those from the B 2Σ+1/2 – X 2Σ+1/2 system were in the visible and ultraviolet regions; and those from the B 2Σ+1/2 – A 2Π3/2, and B 2Σ+1/2 – A 2Π1/2 systems were of visible light. A simple comparison shows that the effect of the spin–orbit coupling on the radiative lifetimes of the A 2Π and B 2Σ+ states was significant. The radiative–lifetime distribution of each level υ versus the rotational quantum number J was evaluated for υ ≤ 15 and J ≤ 70.5.

The potential energy curves (PECs) were calculated for the 27 Λ-S states and 73 Ω states of PO radical. The calculations were done using the CASSCF method, which was followed by the internally contracted multireference configuration interaction (icMRCI) approach. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections as well as Davidson correction were included. Of the 27 Λ-S states, the 16Σ+ state was repulsive at any case. The 14Φ and 16Π states were bound, but they became repulsive with the spin-orbit coupling (SOC) effect accounted for. The 34Σ+, a4Π, C′2Δ, D′2Π, 14Δ, 12Φ, 16Σ+ and 16Π states were inverted with the SOC effect included. The F2Σ+ state had double wells. The avoided crossings existed between the B2Σ+ and F2Σ+ states, the F2Σ+ and 32Σ+ states, the C′2Δ and 22Δ states, the 14Δ and 24Δ states, the 24Δ and 34Δ states, the 24Π and 34Π states and the 34Π and 44Π states. The c4Σ+, 24Σ+, 34Σ+, 34Π, 44Π, 54Π, 34Δ, 14Φ and 16Π states were weakly bound,...

This paper studied the potential energy curves of 30 Ω states yielded from the 14 Λ-S states (X 2 Σ + , 1 2 Π, 2 2 Π, 3 2 Π, 1 2 Σ − , 2 2 Σ + , 3 2 Σ + , 1 2 Δ, 1 4 Σ − , 1 4 Σ + , 2 4 Σ + , 1 4 Π, 2 4 Π, and 1 4 Δ) of the BF + cation. The potential energy curves were calculated for internuclear separations from approximately 0.08 to 1.1 nm using the CASSCF method, which was followed by the icMRCI approach with the aug-cc-pV6Z basis set. Of these 14 Λ-S states, the 2 4 Σ + and 2 4 Π states were repulsive. The 2 2 Π and 3 2 Π states had double wells. The avoided crossings were found between the 1 2 Π and the 2 2 Π state, and between the 3 2 Π and the 4 2 Π state. The 1 2 Π, 2 2 Π, 3 2 Π, and 1 4 Π states were inverted with the spin-orbit coupling effect taken into account. The 1 4 Π state and the second wells of 2 2 Π and 3 2 Π states were weakly bound. Each of the 1 2 Π, 2 2 Π, and 3 2 Π states had one barrier. The potential energy curves of all the Λ-S and Ω states were extrapolated to the complete basis set limit. Core-valence correlation and scalar relativistic corrections were included at the level of an aug-cc-pV5Z basis set. The spin-orbit coupling effect was included by the state interaction approach with the Breit-Pauli Hamiltonian and the all-electron cc-pCV5Z set. The spectroscopic parameters were determined and compared with available experimental and other theoretical ones. The spin-orbit coupling effect on the spectroscopic parameters was evaluated in detail. Comparison with available experimental data show that the methodology used in this paper is highly accurate for this system.

This work computed the potential energy curves of 19 Λ-S states, which arose from the first five dissociation limits of BC+ cation, B+(1Sg) + C(3Pg), B+(1Sg) + C(1Dg), B+(1Sg) + C(1Sg), C+(2Pu) + B(2Pu), and B+(1Sg) + C(5Su). The calculations were done for internuclear separations from 0.08 to 1.07 nm. The potential energy curves of 36 Ω states yielded from these Λ-S states were also calculated. Core-valence correlation and scalar relativistic correction, basis set extrapolation as well as Davidson correction were accounted for. Of these Λ-S states, the c1Σ+, D3Π, 21Π, 23Σ+, 21Δ, 31Σ+, and 41Σ+ had double wells; the 33Π and 31Π states had three wells; the C3Σ− and D3Π states were inverted with the spin-orbit coupling effect included; and the second wells of c1Σ+, D3Π and 31Σ+ states, the second and the third wells of 33Π state as well as the third well of 31Π state were very weakly bound, which well depths were smaller than 400 cm−1. The spectroscopic parameters were determined for all the states....

Theoretical investigations on the potential energy curves of 12 Λ-S states (X 3 Σ − , a 1 Δ, b 1 Σ + , A 3 Π, c 1 Π, 2 3 Π, 2 1 Π, 1 5 Σ − , 2 3 Σ − , 1 3 Δ, 1 1 Σ − , 1 3 Σ + ) of NH radical were made for internuclear separation from about 0.6–11 Ǻ. These Λ-S states correlate to the first three dissociation channels. Of these 12 Λ-S states, the 2 1 Π, 1 5 Σ − , 1 3 Δ, 1 1 Σ − and 1 3 Σ + states are repulsive. The c 1 Π state has one potential barrier. The 2 3 Π and 2 3 Σ − states were found to be bound for the first time. All the PECs were obtained by using CASSCF method followed by the icMRCI approach with Davidson modification. To improve the calculation accuracy, core-valence correlation and scalar relativistic corrections were taken into account. All the 12 Λ-S states split into 25 Ω states when the spin-orbit coupling effect was included. The spectroscopic parameters of all the Ω states were determined. To complement the spectroscopic properties of the NH radical, we included the transition properties and presented the allowed transition dipole moments of four transitions as well as the lifetimes of the corresponding vibrational levels. All results were compared with available measurements and other theoretical ones. Excellent agreement between them was found.

This work investigated the normal spectral emissivity characteristics of Steel 304 over a temperature range from 800 to 1100 K and a wavelength range from 1.4 to 2.1 μm. In the experiments, specimens were heated in air for 6 h at a certain temperature. Two platinum–rhodium thermocouples were symmetrically welded onto the front surface of the specimens near the measuring area for accurate monitoring of the surface temperature. The temperatures measured by the two thermocouples had an uncertainty of 1 K. The average of their readings was regarded as the temperature of the specimen surface. The radiance stemming from the specimens were measured at temperatures from 800 to 1100 K in increments of 20 K by multispectral radiation thermometry. Variation in the normal spectral emissivity with respect to wavelength and temperature was studied for different heating times. The effect of surface oxidization on the accurate prediction of the specimen surface temperature was discussed. Similar variation in the normal spectral emissivity for different heating times showed that the emissivity followed a certain rule. Nine emissivity models were examined for accuracy in the temperature prediction. The results showed that the four-parameter log-linear wavelength and line wavelength emissivity models generated best overall temperature prediction. We concluded that the effect of surface oxidization on the emissivity models of Steel 304 could be dismissed; and that the same models could be used to predict its surface temperature from 800 to 1100 K.

The potential energy curves (PECs) of two lowest dissociation channels of BBr(+) have been thoroughly investigated using the internally contracted multireference configuration interaction method with Davidson correction and relativistic correction. All PECs are extrapolated to complete basis set limit. Several quasibound excited states caused by avoided crossings are found. Based on the PECs, the spectroscopic parameters of bound and quasibound states are obtained. The transition dipole moments and radiative lifetimes are predicted for all possible transitions. Finally, the spin-orbit coupling matrix elements are computed using the states interaction approach with the full Breit-Pauli Hamiltonian to analyze the interactions in PECs crossing regions. We propose that the 2(2)Σ(+)-X(2)Σ(+) and 2(2)Π-X(2)Σ(+) transitions which cannot be observed in experiments are attributed to the intricate couplings among 1(2)Π, 2(2)Π, 2(2)Σ(+), 1(4)Σ(+), 1(4)Δ, 1(4)Σ(-), 1(2)Δ and 1(2)Σ(-) states.

The potential energy curves (PECs) of 9 Λ-S states (X 2 Σ + , 1 4 Σ + , 1 6 Σ + , A 2 Π, 1 4 Π, 1 6 Π, 1 4 Δ, 1 4 Σ − , 2 4 Π) and corresponding 28 Ω states of PN + cation are calculated by the complete active space self-consistent field (CASSCF), which is followed by the internally contracted multireference configuration interaction (icMRCI) with Davidson modification. The calculation is taken into account these effects of spin–orbit coupling, core–valence correlation and scalar relativistic correction. These are found that the 2 4 Π, 1 6 Π and 1 4 Σ − states possess double wells and two avoided crossings occur between the 1 6 Π and 2 6 Π states, the 2 4 Π and 3 4 Π states. Based on the PECs, the spectroscopic parameters are evaluated. And the transitions (transition dipole moments, Franck–Condon Factors and radiative lifetimes) from 1 6 Π −1/2 and 2 4 Π −1/2 (the first well of the two states) to the ground state X 2 Σ + 1/2 are obtained in this paper. These effects of spin–orbit coupling, core–valence correlation and scalar relativistic correction on the spectroscopic calculations are analyzed.

In this paper, ab initio potential energy curves of the first two lowest dissociation channels of AlS have been calculated by using the complete active space self-consistent field (CASSCF) and the internally contracted multireference configuration interaction (icMRCI) method. 13 Λ–S states (X2Σ+, A'2Π, A2Σ+, a4Σ+, b4Δ, c4Σ−, D2Δ, E2Σ−, B2Π, d4Π, e4Π, 22Σ− and 24Σ−) of AlS molecule and the transition properties between these states are reported. The transition properties of A'2Π3/2 _ X2Σ+1/2, and A'2Π1/2 _ X2Σ+1/2 are studied with the effect of spin–orbit coupling (SOC) using the Breit-Pauli Hamiltonian. The accuracy of these potential energy curves is improved the extrapolation of the limit of the complete basis set. The spectroscopic parameters and transition properties reported in this paper are expected to provide useful guidance for future experiments, astronomical observations and theoretical research.

The transition dipole moments of dipole–allowed transitions between the following states were calculated in this study: X1Σ+, A1Π, B1Σ+, C1Δ, D1Σ–, and E1Π; a3Π, b3Σ+, c3Σ–, d3Π, and e3Δ, and those of the spin–forbidden transitions from the a3Π state to the X1Σ+ state of boron monoxide cation. The CASSCF method was used, followed by the valence icMRCI approach. The radiative lifetimes of the vibrational states were of the order of 1 – 10 μs for the A1Π state; 10 ns for the D1Σ–, e3Δ, and the first well of the B1Σ+ states; 1 – 1000 ns for the second well of the B1Σ+ state; 100 ns for the d3Π state; 0.1 – 1 μs for the b3Σ+ and E1Π states; 10 – 100 μs for the C1Δ state; and 10 – 10,000 μs for the c3Σ– state. The transition from the first well of the B1Σ+ state to the X1Σ+ state and that from the double well of the B1Σ+ state to the A1Π state were the strongest, followed by the D1Σ– – A1Π, E1Π – A1Π, d3Π – a3Π, and e3Δ – a3Π transitions. The transition from the second well of the B1Σ+ state to the X1Σ+ state was the weakest, followed by the C1Δ – A1Π, E1Π – B1Σ+, E1Π – C1Δ, E1Π – D1Σ–, c3Σ– – a3Π, and e3Δ – d3Π transitions. The variation in the radiative–lifetime distribution with the rotational angular quantum number J was evaluated. The radiative lifetimes of the vibrational states were of the order of 1 – 10 ms for the a3Π1 state and 10 ms for the a3Π0+ state. The a3Π1 – X1Σ+0+ and a3Π0+ – X1Σ+0+ transitions were weak. The transition properties reported herein may provide useful guidelines for related experimental and theoretical investigations in the near future.

Several experimental groups have measured the rovibrational transitions of B4Σ– – X4Σ–, 24Π – X4Σ–, B4Σ– – A4Π, and d2Σ+ – a2Π systems of diatomic boron carbide. However, no transition properties between any electronic states of this molecule have been calculated. This work studied the transition dipole moments between the X4Σ–, A4Π, B4Σ–, 14Δ, 14Σ+, and 24Π states, between the a2Π, b2Σ–, c2Δ, and d2Σ+ states, and from the a2Π3/2 and a2Π1/2 states to the X4Σ–3/2 and X4Σ–1/2 states. The radiative lifetimes are on the order of 10–2 – 10–4 s for the 14Σ+ state, 10–3 – 10–4 s for the A4Π state, 10–4 s for the 14Δ state, 10–4 – 10–5 s for the c2Δ state, 10–5 s for the b2Σ– and d2Σ+ states, and 10–7 s for the B4Σ– and 24Π states. The B4Σ– – X4Σ–, 24Π – X4Σ–, 24Π – A4Π, and 24Π – B4Σ– transitions are strong. The transitions from the a2Π1/2 and a2Π3/2 states to the X4Σ–1/2 and X4Σ–3/2 states are weak. The emissions originating from the a2Π1/2 and a2Π3/2 states at higher vibrational levels are easier to measure than those at lower levels. The radiative lifetimes are approximately 100 – 103 and 100 – 102 s for the a2Π1/2 and a2Π3/2 states, respectively. The band origins, Franck–Condon factors, and Einstein A coefficients of all dipole–allowed transitions were calculated. The distribution of radiative lifetime varying with rotational angular quantum number was investigated for the A4Π, B4Σ–, 24Π, b2Σ–, and d2Σ+ states. The transition properties reported in this work can provide useful guidelines for future experimental and theoretical studies.

In this work, the potential energy curves of 11 doublet, 11 quartet, and 2 sextet states of a sulfoxide cation are reported and the transition dipole moments between them were calculated. The radiative lifetimes were on the order of 10–6 s for the A2Π, C2Π, b4Σ–, and 12Σ+ states, approximately 10–6 – 10–7 s for the 12Δ and B2Σ– states, and on the order of 10–7 s for the 22Σ+ state. The radiative lifetimes of these states were short, suggesting that the spontaneous emissions generated from them occurred readily. Many transitions are strong, including A2Π – X2Π, C2Π – X2Π, C2Π – A2Π, B2Σ– – X2Π, B2Σ– – A2Π, 12Δ – X2Π, 12Δ – A2Π, and b4Σ– – a4Π. In addition, the transitions from the the first well of the 12Σ+ state to the X2Π state, and from the first well of the 22Σ+ state to the X2Π, A2Π, and C2Π states, are also strong. These strong transitions were easy to measure through spectroscopy. The properties of the transitions between certain Ω states generating from the X2Π, A2Π, a4Π, and b4Σ– states were investigated, including several electric dipole–forbidden transitions. The A2Π1/2 – X2Π1/2, A2Π3/2 – X2Π1/2, b4Σ–3/2 – a4Π5/2, b4Σ–1/2 – a4Π1/2, and b4Σ–1/2 – a4Π3/2 transitions are strong. The radiative litimes of the A2Π1/2, A2Π3/2, a4Π–1/2, a4Π1/2, a4Π3/2, a4Π5/2, b4Σ–1/2, and b4Σ–3/2 states were calculated and the distributions of their radiative lifetime varying as rotational angular momentum quantum number J were studied. The radiative lifetimes of the a4Π1/2 and a4Π3/2 states are on the order of several ms; those of the a4Π5/2 state are approximately several–ten ms; while those of the a4Π–1/2 state are on the order of several s. The results calculated herein can provide some useful guidelines for further experimental and astronomical observations and theoretical studies.