The pure rotational spectrum of ZnS (XΣ)

The pure rotational spectrum of ZnS (X¹Σ⁺) has been measured using direct-absorption millimeter/sub-millimeter techniques in the frequency range 372-471 GHz. This study is the first spectroscopic investigation of this molecule. Spectra originating in four zinc isotopologues (⁶⁴ZnS, ⁶⁶ZnS, ⁶⁸ZnS, and ⁶⁷ZnS) were recorded in natural abundance in the ground vibrational state, and data from the v = 1 state were also measured for the two most abundant zinc species. Spectroscopic constants have been subsequently determined, and equilibrium parameters have been estimated. The equilibrium bond length was calculated to be r_e ∼ 2.0464 Å, which agrees well with theoretical predictions. In contrast, the dissociation energy of D_E ∼ 3.12 eV calculated for ZnS, assuming a Morse potential, was significantly higher than past experimental and theoretical estimates, suggesting diabatic interaction with other potentials that lower the effective dissociation energy. Although ZnS is isovalent with ZnO, there appear to be subtle differences in bonding between the two species, as suggested by their respective force constants and bond length trends in the 3d series.     

Potential energy functions for the ground state X3Σ- and excited state 1Σ+ of UO

Based on group theory and atomic and molecular reactive statics (AMRS), the ground state X³Σ^? and excited state ¹Σ⁺ of UO and their reasonable dissociation limits are derived successfully. Using the MP2 method with the relativistic e? ective core potential and valence electron basis set (5s4p3d4f)/[3s3p2d2f] for the U atom and basis set 6-311G* for the O atom, the present work has calculated the potential energy curves for the ground state Χ³Σ^? and excited state ¹Σ⁺ of UO. The equilibrium distance and dissociation energy are 0.1833 nm and 6.9241 eV for the Χ³Σ^? state, and 0.1825 nm and 8.8756eV for the ¹Σ⁺ state. Spectroscopic data are derived for the first time.     

Calculation of spectroscopic constants and radiative parameters for the B 1Π-X 1Σ+ electronic transitions of NaK,NaRb, and NaCs molecules

The vibrational, rotational, and centrifugal spectroscopic constants and the radiative parameters (the Einstein coefficients, oscillator strengths, Frank-Condon factors, r _v′v″ centroids, and wavenumbers of rotational lines) of electronic-vibrational-rotational transitions in the systems of bands B ¹Π -X ¹Σ⁺ of NaK (0 ≤ v′ ? 14, 0 ≤ v″ ≤ 52, j = 0, 30, 50, 70, 80, and 100), NaRb (0 ≤ v′ ≤ 12, 0 ≤ v″ ≤ 51, j = 0, 20, 30, 50, 70, 90, 100, and 120), and NaCs (0 ≤ v′ ≤ 10, 0 ≤ v″ ≤ 44, j = 0, 30, 50, 70, 90, 100, and 120) molecules, as well as the radiative lifetimes of excited electronic states, are calculated. Calculations are performed based on semiempirical potential curves constructed in this work. The calculated spectroscopic constants and the radiative lifetimes are compared with experimental values.     

Rotational and rovibrational transitions in the a 1Δ2 and b 1Σ+0+ states of sulfur monoxide radical

ABSTRACT

Sulfur monoxide radical has widely been detected in outer space using ground-state spectroscopy. The a ¹Δ₂ and b ¹Σ⁺₀₊ states of this radical have low excitation energies, and they possibly exist in outer space. In this work, the potential energy curves and dipole moment functions of the two states were evaluated using the complete active space self- consistent field method, followed by the valence internally contracted multireference configuration interaction approach. The transition line positions, oscillator strengths, band transition dipole matrix elements, Einstein A coefficients, and Franck–Condon factors of all transitions were calculated for lower vibrational levels at rotational angular momentum quantum number J up to 150. The transition line positions calculated in this study are in good agreement with the experimental results. The rovibrational transition became noticeably weak at Δυ > 5. Comparing the results of a ¹Δ₂ and b ¹Σ⁺₀₊ states reported in this paper with the previous values, we conclude that these results are the most accurate and complete to date.     

Vibrational Analysis of the A3Π0−X1Σ+ and B3Π1−X1Σ+ Subsystems of the GaBr Molecule

Abstract

The emission band spectrum of gallium monobromide has been excited in a dc hollow cathode discharge. bands of the ³Π_0,1?X¹Σ⁺ system, lying in the range from 340 to 370 nm have been recorded at high resolution and measured. The previous vibrational analysis has been revised and corrected. New vibrational assignment has been proposed and improved vibrational constants of the upper and lower electronic states have been determined.     

A Reanalysis of theA1Π–X1Σ+Transition of AlBr

TheA¹Π–X¹Σ⁺transition of aluminum monobromide (AlBr) near 2800 Å was recorded using a Bruker IFS 120 HR Fourier transform spectrometer at nominal resolutions of 4 and 0.03 cm⁻¹. All bands showP,Q, andRbranches and all are degraded to longer wavelengths. The 0–0 band is the most intense and the Δv= 0 sequence dominates the observed spectrum. Each band appears doubled due to the natural isotopic abundances of⁷⁹Br (50.69%) and⁸¹Br (49.31%). Band origin shifts due to isotopic substitution of bromine were examined to confirm the assignments of isotopic species. The rotational structure of the 0–1, 1–2, 0–0, 1–1, and 2–2 bands was assigned and fitted. These data were merged with previously reported photographic data for the 1–0, 2–1, 3–2, 2–0, and 3–1 bands and also infrared and microwave measurements to provide an improved set of constants for both electronic states. The rotational constants for each vibrational level in theX¹Σ⁺state vary smoothly with increasing vibrational quantum number and thus an expansion of the constants in terms of equilibrium values is recommended. An expansion of theA¹Π rotational constants in terms of equilibrium values is not recommended as the distortion constants do not change smoothly with increasing vibrational quantum number. Therefore, the rotational constants for theA¹Π state were determined for each individual vibrational level. This approach leads to vastly improved vibrational constants for theA¹Π state by reducing correlations between rotational and vibrational constants. This problem is serious for theA¹Π state owing to severe departures from harmonic behavior in thev= 2 andv= 3 levels.     

Rovibrational transition properties of the X1Σ+ and A1Π states of carbon monosulfide

Carbon monosulfide was detected in outer space by rovibrational spectroscopy of the X ¹Σ⁺ state and A ¹Π – X ¹Σ⁺ system. This work calculated the potential energy curves and dipole moment functions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states, and computed the transition dipole moments between the two states employing the CASSCF method, followed by the valence icMRCI approach. Core-valence correlation and scalar relativistic corrections were included. The extrapolation of potential energies to the complete basis set limit was performed. The spin-orbit coupling effect was included. The Einstein A coefficients, band origins, and oscillator strengths were calculated for the rovibrational transitions when J?≤?150. The rovibrational transitions of the X ¹Σ⁺ ₀₊ and A ¹Π₁ states became very weak when Δυ?≥?6. The Einstein A coefficients of vibronic emissions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were large, indicating that the emissions were able to be measured easily through spectroscopy. Several rovibrational transitions of the A ¹Π₁ – X ¹Σ⁺ ₀₊ system were analysed in detail. The distribution of radiative lifetime varying as rotational quantum number was calculated. The results obtained in this work agree well with the available experimental values.     

Measurements and calculations of H2-broadening and shift parameters of water vapour transitions of the ν1 + ν2 + ν3 band

The water vapour line broadening and shifting for 97 lines in the ν₁ + ν₂ + ν₃ band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm^?1 and in a wide pressure range of H₂. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν₂, ν₁, and ν₃ vibrational bands are presented.     

Vibrational and rotational excitation effects of the N(2D) + D2(X1Σg +) → ND(X3Σ+) + D(2S) reaction

The effects of the rovibrational excitation of reactants in the N(²D) + D₂(X¹Σ_g⁺) → ND(X³Σ⁺) + D(²S) reaction are calculated in a collision energy range from the threshold to 1.0 eV using the time-dependent wave packet approach and a second-order split operator. The reaction probability, integral cross-section, differential cross-section and rate constant of the title reaction are calculated. The integral cross-section and rate constant of the initial states v = 0, j = 0, 1, are in good agreement with experimental data available in the literature. The rotational excitation of the D₂ molecule has little effect on reaction probability, integral cross-section and the rate constant, but it increased the sideways and forward scattering signals. The vibrational excitation of the D₂ molecule reduced the threshold and broke up the forward–backward symmetry of the differential cross-section; it also increased the forward scattering signals. This may be because the vibrational excitation of the D₂ molecule reduced the lifetime of the intermediate complex.     

The pure rotational spectrum of ZnO in the XΣ and aΠi states

The pure rotational spectrum of ZnO has been measured in its ground X¹Σ⁺ and excited a³Π_i states using direct-absorption methods in the frequency range 239-514 GHz. This molecule was synthesized by reacting zinc vapor, generated in a Broida-type oven, with N₂O under DC discharge conditions. In the X¹Σ⁺ state, five to eight rotational transitions were recorded for each of the five isotopologues of this species (⁶⁴ZnO, ⁶⁶ZnO, ⁶⁷ZnO, ⁶⁸ZnO, and ⁷⁰ZnO) in the ground and several vibrational states (v = 1-4). Transitions for three isotopologues (⁶⁴ZnO, ⁶⁶ZnO, and ⁶⁸ZnO) were measured in the a³Π_i state for the v = 0 level, as well as from the v = 1 state of the main isotopologue. All three spin-orbit components were observed in the a³Π_i state, each exhibiting splittings due to lambda-doubling. Rotational constants were determined for the X¹Σ⁺ state of zinc oxide. The a³Π_i state data were fit with a Hund’s case (a) Hamiltonian, and rotational, spin-orbit, spin-spin, and lambda-doubling constants were established. Equilibrium parameters were also determined for both states. The equilibrium bond length determined for ZnO in the X¹Σ⁺ state is 1.7047 Å, and it increases to 1.8436 Å for the a excited state, consistent with a change from a π⁴ to a π³σ¹ configuration. The estimated vibrational constants of ω_e ∼ 738 and 562 cm⁻¹ for the ground and a state agreed well with prior theoretical and experimental investigations; however, the estimated dissociation energy of 2.02 eV for the a³Π_i state is significantly higher than previous predictions. The lambda-doubling constants suggest a low-lying ³Σ state.     

High-precision laser and RF spectroscopy of the spin-rotation and HFS interactions in the X2Σ+ and B2Σ+ states of LaO

The spin-rotation and hyperfine interactions in the X²Σ⁺ and B²Σ⁺ electronic states of ¹³⁹La¹⁶O have been studied using Doppler-free laser-induced fluorescence and molecular-beam laser-rf double resonance. Observations were made for several values of v and many values of N, allowing evaluation of the principal interaction strengths and their N and v dependences for both the X and B states. The results are compared with earlier results for the isoelectronic system ¹³⁷Ba¹⁹F.     

Ab initio configuration interaction study on the electronic structure of the X2Σ+, B2Σ+ and 32Σ+ states of SiO+

The energy levels and electronic structure of the X²Σ⁺, B²Σ⁺ and 3²Σ⁺ states of SiO⁺ are studied using ab initio configuration interaction (CI) calculations at and around their equilibrium internuclear distances R _e. Spectroscopic constants and the vertical excitation energy from the SiO⁺ X²Σ⁺ state are predicted for the 3²Σ⁺ state. Based on the calculated CI wavefunctions, avoided crossings of the potential energy curve for the 3²Σ⁺ state and a near-degeneracy effect in the avoided crossing region are examined. The effects of the mixing of excited configuration state functions in the total electronic wavefunctions for the 1–3 ²Σ⁺ states are investigated by analysing correlation energies in terms of the contributions from classes of excited configurations. The importance of both the near-degeneracy effect and the correlation energy effect in describing correctly the electronic structure of the 3 ²Σ⁺ state in the neighbourhood of its R _e is discussed.     

Dielectric functions and interband transitions of InxAl1 − xP alloys

We report pseudodielectric functions <ε> from 1.5 to 6.0 eV of In_xAl_1 − xP ternary alloy films. Data were obtained by spectroscopic ellipsometry on 1.2 μm thick films grown on (001) GaAs substrates by molecular beam epitaxy. Artifacts were minimized by real-time assessment of overlayer removal, leading to accurate representations of the bulk dielectric responses of these materials. Critical-point (CP) energies were obtained from numerically calculated second energy derivatives, and their Brillouin-zone origins identified by band-structure calculations using the linear augmented Slater-type orbital method.     

LiH分子X 1Σ+、 A 1Σ+和B 1Π态的势能函数

利用SAC/SAC-CI方法,使用D95(d)、6-311G**及cc-PVTZ等基组,对LiH分子的基态(X1Σ+)、第一激发态(A1Σ+)及第二简并激发态(B1Π)的平衡结构和谐振频率进行了优化计算.通过对三个基组的计算结果的比较,得出了D95(d)基组为三个基组中的最优基组的结论;使用D95(d)基组,利用SAC的GSUM(GroupSumofOperators)方法对基态(X1Σ+)、SAC-CI的GSUM方法对激发态(A1Σ+和B1Π)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X1Σ+)相对应的光谱常数,结果与实验数据较为一致.     

Polarization spectroscopy of Na2 A1Σu+-b3Πu ← X1Σg+ intercombination bands

The A¹Σ_u⁺ ∼ b³Π_u perturbation of Na₂ in several high vibrational levels has been studied by polarization spectroscopy. Deperturbed molecular constants are given for the mutually interacting v_A = 26 ∼ v_b = 28 and v_A = 34 ∼ v_b = 34 vibrational levels.     

Rotational Analysis of the 1–4 Band of the B 2Σ+–X 2Σ+ System of 14C16O+

ABSTRACT

High-resolution emission spectrum of the 1–4 band of the B ²Σ⁺–X ²Σ⁺ transition of ¹⁴C¹⁶O⁺ was observed for the first time by conventional emission spectroscopy. The band spectrum was excited in a water-cooled Geissler lamp filled with commercial gaseous carbon monoxide enriched in about 80% of the radiocarbon ¹⁴C. A rotational analysis has been carried out and obtained molecular constants have been merged with previously published data for the B ²Σ⁺–A ²Π_i and A ²Π_i–X ²Σ⁺ transitions. The principal equilibrium constants for the ground X ²Σ⁺ state obtained from this work are ω_e = 2121.7726(98), ω_e x _e = 13.9055(27), B _e = 1.815290(30), α_e = 1.6594(33) × 10^?2, and γ_e = ? 0.377(73) × 10^?4 cm^?1. Also, presently known experimental equilibrium molecular constants of the X ²Σ⁺ states of the CO⁺ isotopic molecules are summarized and isotopic dependence of the B _e and ω _e constants is discussed.     

碰撞诱导钠分子A1Σ+u→X1Σ+g的荧光光谱

用532.0 nm激光激发Na2分子到B1Πu电子态,记录了Na(3P)原子的跃迁和Na2分子的A1Σ+u-Χ1Σ+g的谱带.由Na与Na2激发态发射的光谱及其强度可以认定在Na-Na2系统中的碰撞过程,Na(3P)原子线是Na2(B1Πu)到Na(3P)的碰撞能量转移产生的,预解离过程也可产生原子线.而A1Σ+u-Χ1Σ+g谱带是由B1Πu到21Σ+g的碰撞转移后再由21Σ+g到A1Σ+u的辐射而引起的.在360℃,根据辐射衰变率和荧光强度,得到Na2(B1Πu)到Na2(21Σ+g)碰撞转移率系数为7.1×10-10 cm3s-1,而B1Πu的预解离率为2.3×106 s-1.     

Near-resonant electronic energy transfer induced by first- and second-order long-range potentials between the two states A1Σu+ and X1Σg+ of Li2 and Na2

Collision-induced rotational transitions between different electronic states are treated theoretically in the Born approximation for a second-order long-range interaction potential. It is shown that the experimentally observed cross sections for resonant channels in the A → X transfer of Li₂ are reproduced by this simple calculation taking the two terms' first-order dipole-dipole and second-order interaction potentials into consideration.     

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

ABSTRACT

This 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.