Rotationless Radiative Lifetimes Research Articles

Multireference configuration interaction calculations on the FeS molecule

ABSTRACT High-level ab initio calculations for the A-X and the a-X band systems of the FeS molecule are here reported. For such, potential energy curves are calculated using the multireference configuration interaction (MRCI) method. Subsequently, the computed interaction energies were fitted to an analytical representation and a new set of spectroscopic parameters was derived. The calculations predict a dissociation energy of 27,015 cm for the X, in agreement with recent experimental measurements. The similarity between X and A is considerable, showing an energy separation of only 953 . The spin-orbit coupling (SOC) effect was considered by using the Breit-Pauli operator (). At the equilibrium distance, the obtained SOC constant for the ground state is (X)= −206.6 cm. The rotationless radiative lifetimes for the A and a excited states are in the orders of milli- and microseconds, respectively, indicating that the vibronic emissions of the A-X system are too weak to be observed.

Radiative lifetimes of the doublet states of 107Ag16O: A configuration interaction study

Potential energy curves and a new set of spectroscopic parameters have been calculated for the X 2 Π , A 2 Σ + , and C 2 Π states. The RKR potential for the D 2 Π state is also included in our analysis. The dissociation energy of 15,970 cm −1 was derived for the ground electronic state, in good agreement with the most recent experimental measurement. The obtained rotationless radiative lifetimes for the lower states A 2 Σ + , C 2 Π , and D 2 Π of AgO are in the orders of microseconds. The spin–orbit coupling effect is accounted for using the Breit-Pauli Hamiltonian. Theoretical A v values have been calculated for the X 2 Π ( v = 0–15) and C 2 Π ( v = 0–5), showing the inverted character of these states.

Theoretical study of the low-lying doublet and quartet electronic states of 7Li16O molecule including spin-orbit coupling effect and a new limit to the adiabatic ionization energy

Abstract The potential energy curves of 7Li16O molecule for energies below 50,000 cm−1 have been investigated. All doublet and quartet electronic states considered here are studied at the CASSCF/icMRCI(Q) level of theory associated with the aug-cc-pV5Z basis set. Within this range of energies, analytical representations are proposed. To evaluate the accuracy of these functional forms, a novel set of spectroscopic parameters have been derived. Transition probability parameters as the Franck–Condon factors and Einstein A coefficients of certain vibronic emissions from the A 2 Σ + - X 2 Π , 2 2 Π - X 2 Π , and 2 2 Π - A 2 Σ + band systems are reported. It was found that rotationless radiative lifetimes of the order of milliseconds are determined for A-X and C-X bands. Overall, our results transition probabilities suggest that these vibronic emissions are weak and, therefore, difficult to measure in spectroscopy experiments. Additionally, we obtained an adiabatic ionization energy value of 68,002 cm−1.

Vibronic emissions and radiative lifetimes for a3Σ+, b3Π, c3Σ+, d3Δ, and e 3Σ– states of silicon monoxide

In this study, the potential energy curves of the a3Σ+, b3Π, c3Σ+, d3Δ, and e3Σ– states of the silicon monoxide are calculated and the transition dipole moments between them are computed using the complete active space self–consistent field, which is followed by the valence internally contracted multireference configuration interaction approach. The Davidson correction, core–valence correlation and scalar relativistic corrections are considered. The extrapolation of the potential energies to the complete basis set limit is included. The band origins, Einstein A coefficients, and Franck–Condon factors of all vibronic emissions between these five states are calculated. The rotationless radiative lifetimes are approximately 10–1 to 10–4 s for the b3Π state, 10–2 to 10–4 s for the d3Δ state, and 10–3 to 10–4 s for the e3Σ– state. The radiative lifetime quickly becomes shorter as the vibrational level increases for the three states. The lifetime is of the order of 100 ns for all vibrational levels of the c3Σ+ state, indicating that the spontaneous vibronic emissions originating from this state occurs easily. Overall, the vibronic emissions of the b3Π – a3Σ+, d3Δ – b3Π, and e3Σ– – b3Π systems are weak, suggesting that they are difficult to measure through spectroscopy. The vibronic emissions of the c3Σ+ – a3Σ+ and c3Σ+ – b3Π systems are strong, indicating that they are easy to measure in a spectroscopy experiment. The radiative lifetime with the variation of rotational angular momentum quantum number is discussed briefly for υ ≤ 15 and J ≤ 30 of the b3Π, c3Σ+, d3Δ, and e3Σ– states. The results indicate that the radiative lifetime changes only over a small range for each triplet state. The transition properties calculated in this study can be used to explain why only a few experimental transition properties are currently available for these triplet states.

Vibronic emissions between the X 1Σ+, A 1Π, C 1Σ−, D 1Δ, and E 1Σ+ states of silicon monoxide

The potential energy curves of the X 1Σ+, A 1Π, C 1Σ−, D 1Δ, and E 1Σ+ singlet states of silicon monoxide are calculated using the complete active space self-consistent field method, followed by the valence internally contracted multireference configuration interaction approach. The transition dipole moments between these states are computed. To calculate the potential energy curves accurately, core-valence correlation and scalar relativistic corrections are accounted for and the extrapolation of the potential energies to the complete basis set limit is included. The rotationless radiative lifetimes are of the order of 10 ns for all vibrational levels of the A 1Π and E 1Σ+ states, suggesting that spontaneous vibronic emissions originating from the two states occur easily. The band origins, Einstein A coefficients, and Franck–Condon factors of all the vibronic emissions are calculated. Overall, the Einstein A coefficients of numerous spontaneous emissions from the A 1Π–X 1Σ+ and E 1Σ+–X 1Σ+ systems are large, suggesting that these vibronic emissions are strong and therefore easy to measure through spectroscopy. The Einstein A coefficients of all the vibronic emissions from the E 1Σ+–A 1Π system are small, predicting that the E 1Σ+–A 1Π transition is weak and therefore difficult to detect through experiment, regardless of the total radiative lifetimes of the E 1Σ+ state. The distribution of radiative lifetime with the variation of the rotational quantum number J is discussed briefly for the υ ≤ 15 and J ≤ 30 levels of the A 1Π and E 1Σ+ states. At a certain υ, the radiative lifetime slowly increases as the J increases for the A 1Π state, whereas it is almost constant for any J of the E 1Σ+ state.

Dipole-allowed transitions between the X3Σ−, A′3∆, A′′3Σ+, A3Π, B3Σ−, and C3Π states of the sulfur monoxide radical

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.

Vibronic emissions between the a1Σ+, b1Π, c1Δ, d1Σ+, e1Σ−, and f1Π states of the diatomic silicon carbide SiC

In recent years, emissions of silicon carbide molecule have been widely detected in carbon stars, stellar atmospheres, and interstellar molecular clouds. In order to evaluate the vibronic transitions between different singlet states of this molecule, we calculate the potential energy curves of the a1Σ+, b1Π, c1Δ, d1Σ+, e1Σ−, and f1Π states and compute the transition dipole moments between them. The band origins, Einstein A coefficients, and Franck–Condon factors of the vibronic emissions are computed for all possible transitions between these six lowest-lying states. Of these vibronic transitions, only the emissions of the d1Σ+–b1Π and f1Π–b1Π systems are strong. The emissions of the f1Π–a1Σ+ system are so weak that it is very difficult to measure them through spectroscopy. The rotationless radiative lifetimes are approximately several microseconds for all vibrational levels of the d1Σ+ and f1Π states, indicating that the vibronic emissions originating from the two states occur easily. The rotationless radiative lifetimes are approximately several ms for all vibrational levels of the e1Σ− state. Based on the Einstein A coefficients, we conclude that it is difficult to measure these emissions generated from the e1Σ− state, regardless of the radiative lifetime. The rotationless radiative lifetimes are of the order of 10−3–10−4 s for all vibrational levels of the b1Π and c1Δ states. The transition probabilities reported in this study can be employed to explain why the emissions between the singlet states of this molecule have rarely been measured to date, both in a spectroscopy experiment and in outer space.

Transition probabilities of the X1Σ+, A1Π, B1Δ, C1Σ+, and D1Π states of the AlO+ cation

ABSTRACTThis study computes the potential energy curves of the X1Σ+, A1Π, B1Δ, C1Σ+, and D1Π states of AlO+ cation and the transition dipole moments between them. The orders of the rotationless radiative lifetimes are 10–100 μs for the A1Π state, 1–1000 ms for the B1Δ state, 10 ns for the first well and 100 ns for the second well of the C1Σ+ state, and 1 μs for the D1Π state. Emissions of the B1Δ–A1Π and D1Π–C1Σ+ systems are so weak that they are hardly measured via spectroscopy, the emissions of the C1Σ+–X1Σ+, C1Σ+–A1Π, and D1Π–X1Σ+ systems are so strong that they can be detected readily, and emissions of the A1Π–X1Σ+ and D1Π–A1Π systems can be observed through spectroscopy only by a significant effort. There is a strong great similarity between spontaneous emissions of the A1Π–X1Σ+ system of the AlO+ cation and the A2Π–X2Σ+ system of the AlO radical. The emissions of the A2Π–X2Σ+ system of the AlO radical have been measured in outer space Therefore, it is highly possible that the emissions of the A1Π–X1Σ+ system of the AlO+ cation can be detected in the astrophysical media.

Rotationless radiative lifetimes and transition probabilities of the seven lowest-lying doublet states of the AlO radical

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 Schrödinger 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.

Spontaneous emissions between the a3Π, b3Σ-, c3Σ+, d3Π, and e3Σ- states of the AlO+ cation.

The potential energy curves are calculated for the a3Π, b3Σ-, c3Σ+, d3Π, and e3Σ- states of the AlO+ cation using the valence internally contracted multireference configuration interaction approach. The transition dipole moments are computed between these states. To improve the reliability and accuracy of the potential energy curves, several corrections are included, namely, Davidson correction, core-valence correlation and scalar relativistic corrections, as well as extrapolation of the potential energies to the complete basis set limit. The rotationless radiative lifetimes of all vibrational levels are of the orders of 10-1 to 105 s for the b3Σ- state, which are so long that the transitions generating from the b3Σ- state are almost impossible to occur. Those are several ten to several hundred ns for the e3Σ- state, and several μs for the c3Σ+ and d3Π states, which indicate that the transitions originating from the e3Σ-, c3Σ+, and d3Π states occur easily. The largest Einstein coefficient of the transitions from the b3Σ--a3Π system is approximately 10-1, suggesting that these transitions are too weak to be recorded through spectroscopy. The Einstein coefficients of many transitions from the c3Σ+-a3Π, d3Π-a3Π, d3Π-c3Σ+, and e3Σ--a3Π systems are large, indicating that these transitions are able to be measured via spectroscopy. The transition properties reported in this study can be employed to detect the spectroscopy from the AlO+ cation both in outer space and in experiment.

Transition dipole moments and transition probabilities of the NS radical

In this work, spectroscopic parameters and transition properties are studied for the X 2Π, B 2Π, B′ 2Σ+, a 4Π, and b 4Σ− states of the NS radical. It is found that the rotationless radiative lifetimes of the vibrational levels are approximately several µs for the B 2Π state, in order of 10 µs for the B ′Σ+ state, and 10 to 100 µs for the b 4Σ− state. Therefore, vibronic emissions originating from them occur readily. The Einstein coefficients of the vibronic emissions from the B 2Π–X 2Π, B ′2Σ+–X 2Π, and b 4Σ−–a 4Π are large, indicating that the transitions of these systems can be measured readily through spectroscopy. The effect of the spin–orbit coupling effect on the spectroscopic parameters is evaluated for these five states. The splitting energies of the X 2Π and B 2Π states are 221.67 and 95.05 cm−1 at the internuclear equilibrium positions, respectively. The transition properties for each pair of Ω states are calculated and the results calculated compared with available experimental ones. The spectral range of vibronic emissions is determined for the transitions of several- pair Ω states.

Radiative lifetimes of vibrational levels and transition probabilities of spontaneous emissions of the six lowest-lying triplet states of AlN radical.

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.

Transition probabilities between the X3Π, A3Σ−, B3Σ+, C3Π, D3Δ, and E3Π states of SiC molecules

In this study, we calculated the potential energy curves of the X3Π, A3Σ−, B3Σ+, C3Π, D3Δ, and E3Π states of SiC molecules and the transition probabilities between them. The rotationless radiative lifetimes of the vibrational levels are in the order of 10−5 s for the A3Σ− state, 10−5–10−6 s for the B3Σ+ state, and 10−6 to 10−7 s for the C3Π and E3Π states. This suggests that the spontaneous emissions originating from these states can easily occur. The rotationless radiative lifetimes vary in the range of 10−3–10−5 s for the vibrational levels of the D3Δ state. The lifetime of the D3Δ state rapidly decreases with the increasing vibrational level, indicating that the occurrence of spontaneous emissions originating from this state at lower levels is more inhibited than those at higher levels. The emissions of the A3Σ−–X3Π, B3Σ+–X3Π, C3Π–X3Π, C3Π–A3Σ−, D3Δ–X3Π, and E3Π–X3Π system are strong, suggesting that these transitions can be measured easily by spectroscopy. The emissions of the D3Δ–C3Π and E3Π–D3Δ systems are weak, suggesting that these transitions are difficult to detect by spectroscopy. The spectral range of the strong emissions from the A3Σ−–X3Π system is in the infrared region. The strong emissions of the B3Σ+–X3Π, C3Π–X3Π, and C3Π–A3Σ− systems are of visible light. Some of these strong emissions, especially those from the A3Σ−–X3Π system, could be expected to be detectable in carbon star IRC + 10,126 and the circumstellar shell.

Transition probabilities of the seven lowest–lying singlet states of the AlN radical

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.

Rotationless radiative lifetimes and transition probabilities of some low-lying quintet states of the NS+ cation

Recently, the NS+ cation has been detected via spectroscopy as an interstellar species. To determine its transition properties, the potential energy curves of one singlet state and seven quintet states are investigated. For the eight states, the potential energy curves and transition dipole moments are calculated using the complete active space self-consistent field method followed by the valence internally contracted multireference configuration interaction approach. The spectroscopic parameters and transition dipole moments are compared with the available experimental and other theoretical results. The band origins, Franck–Condon factors, and Einstein coefficients of the spontaneous emissions are calculated for the transitions of 15 pairs of quintet states. It is found that the 15Π–15Σ+, 25Σ+ –15Σ+, 25Π–15Σ+, and 35Σ+–15Σ+ transitions can be detected in a spectroscopy experiment. The rotationless radiative lifetimes of the vibrational levels are approximately 10−5 to 10−6 s for the 25Σ+ state, 10−5 s for the 15Π state, and 10−4–10−5 s for the 35Σ+ and 25Π states. The radiative lifetimes of the vibrational levels are so long that it is rather difficult for the spontaneous emissions generated from the 15Δ and 25Δ states to occur, and the emissions from the two states are very difficult to observe via spectroscopy. The reasons may be that both the 15Δ and 25Δ states have long internuclear equilibrium separations, and the transition dipole moments originating from them are very small. The results reported in this work can be used to detect the NS+ cation in cold molecular clouds, prestellar cores, and shocks.

Transition Probabilities of Emissions and Rotationless Radiative Lifetimes of Vibrational Levels for the SiN Radical

Abstract The transition dipole moments of the SiN radical are calculated by the valence internally contracted multireference configuration interaction (icMRCI) approach with the aug-cc-pV6Z basis set. The transition probabilities of spontaneous emissions are computed between the eight lowest-lying doublet states. The vibrational band origins, Einstein coefficients, and Franck–Condon factors of all the spontaneous emissions involved are evaluated. The rotationless radiative lifetimes of the first 15 vibrational levels were determined to be approximately 10−3–10−5 s long for the A2Π state, 10−3–10−7 s long for the F2Π state, 10−6–10−7 s long for the C2Π state, 10−6 s long for the D2Σ− and E2Δ states, and 10−7 s long for the B2Σ+ and G2Δ states. It is observed that the rotationless radiative lifetimes quickly become shorter, with an increase in the vibrational level for the A2Π and F2Π states. The Einstein coefficients of many emissions are large for the B2Σ+–X2Σ+, B2Σ+–A2Π, C2Π–X2Σ+, C2Π–A2Π, D2Σ−–A2Π, E2Δ–A2Π, F2Π–X2Σ+, F2Π–A2Π, and G2Δ–A2Π systems. However, the emissions are very weak for the F2Π–D2Σ− system. The vibrational levels and rotational constants of each state are determined and the spectral range of each transition system is evaluated. The vibrational band origins are compared with the available experimental ones. The spectroscopic routines for detecting the unobserved states are proposed. These results can be employed to measure emissions, in particular those of interstellar clouds and stellar atmospheres.

Spectroscopic properties and transition probabilities of SiC+ cation

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.

Transition Probabilities of Emissions and Rotationless Radiative Lifetimes of Vibrational Levels for the PO Radical

Abstract This work investigates the transition dipole moments (TDMs) and transition probabilities of electric dipole emissions between the X2Π, B2Σ+, B′2Π, D′2Π, C2Σ−, C′2Δ, F2Σ+, and P2Π states of the PO radical. The TDMs of 23 pairs of states are calculated by the internally contracted multireference configuration method with the aug-cc-pV6Z basis set. The vibrational band origins, Franck–Condon factors, and Einstein coefficients of all the spontaneous emissions are evaluated. The rotationless radiative lifetimes of the vibrational levels are approximately 10−7–10−8 s for the B2Σ+, C2Σ−, C′2Δ, P2Π, and F2Σ+ states; 10−4–10−5 s for the B′2Π state; and 10−1–10−2 s for the D′2Π state. The Einstein coefficients of many emissions are large for the B2Σ+–X2Π, B′2Π–X2Π, C′2Δ–X2Π, C2Σ−–X2Π, F2Σ+–X2Π, P2Π–X2Π, P2Π–B′2Π, and P2Π–D′2Π systems. Almost all the spontaneous emissions arising from the D′2Π state are very weak. The vibrational band origins of these emissions extend from the UV into the far-infrared spectra. The radiative lifetimes and vibrational band origins are compared with available experimental and theoretical values. According to the radiative lifetimes and transition probabilities obtained in this paper, some guidelines for detecting these states spectroscopically are proposed. The TDMs and transition probabilities reported here are considered to be reliable and can be used as guidelines for detecting similar transitions, especially those in interstellar space.

Nonadiabatic Predissociation Studies of the (1-3) 3Π g System of Al 2 by Means of a Complex Rotated Finite Element Method

A general numerical Runge–Kutta–Fehlberg based diabatization procedure for electronic states in diatomics was applied to the adiabatic (1-3) 3Π g system of Al 2 in order to obtain a strictly diabatic basis. Using an exterior complex rotated finite element method, adiabatic Born–Oppenheimer (BO) as well as diabatic rovibronic term energy values and predissociation widths for the (2) 3Π g ; ( v, N)=(0−50, 0−25) and (3) 3Π g ; ( v, N)=(0−17, 0−25) levels were computed. Comparing rotationless BO and diabatic energies, differences between 10 and 25 cm −1 are found for the (2) 3Π g levels while the (3) 3Π g levels display an almost constant shift ∼12 cm −1. From the widths, the nonradiative lifetime for each rovibronic level was calculated. Based on existing rotationless radiative lifetimes, an estimation of an upper limit of about 50 ns was used to determine a number of rovibronic (2, 3) 3Π g levels which may be experimentally observed.

Molecular constants for the 1?+ ground state of the ArH+ ion

From the near equilibrium PNO-CEPA potential and dipole moment curves the following molecular constants for the 1Σ+ ground state of the ArH+ ion have been calculated: re = 1.286A, ωe = 2723 cm−1, ωeχe = 56 cm−1, D0 = 3.89 eV and μ0 = 2.384 D. The rotationless radiative lifetimes of the five lowest vibrational states are predicted to be 2.28, 1.2, 0.85, 0.64, 0.46 for ArH+ and 9.09, 4.71, 3.27, 2.55 and 2.11 for ArD+, respectively (all values are in milliseconds and in ascending order of the vibrational levels).