Calculation of molecular constants for the X 1Σ g + , A 1Σ u + , B 1Πu, and a 3Σ u + electronic states of 39K2

The molecular constants are calculated for the X ¹Σ _g ⁺ , A ¹Σ _u ⁺ , B ¹Π_u, and a ³Σ _u ⁺ and electronic states of a potassium dimer. The wave functions and vibrational energies necessary for calculating the molecular constants are determined by solving the radial wave equation with the use of potential energy curves constructed by the semiempirical method. The vibrational terms, the rotational constants, and the centrifugal distortion constants calculated from the potential curves are compared with those determined from the experimental data.     

Rotational analysis of weak (4, 6) hot band in the comet-tail (AΠi-XΣ) system of the CO

The ro-vibrational spectrum of the weak (4, 6) hot band in the comet-tail (A²Π_i-X²Σ⁺) system of CO⁺ is observed by employing optical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy. One hundred and twenty-four spectral lines are assigned to this band; thus, precise molecular constants of the levels involved are obtained from a weighted nonlinear least-squares fitting procedure combining with our previous spectrum of the (3, 6) band.     

Absorption spectrum of the (2, 1) band in the AПi-XΣ system of CS cation

The spectrum of CS⁺ cation was recorded in the 12,235-12,600 cm⁻¹ region by employing optical heterodyne velocity modulation absorption spectroscopy. In combination with simultaneous measurement of optical heterodyne concentration modulation absorption spectroscopy, the spectral lines of CS⁺ blended with the neutral CS lines were identified and extracted from the observed spectra. One hundred and eighty-two spectral lines of CS⁺ were assigned to the (2, 1) band in the A²П_i-X²Σ⁺ system and the improved molecular constants of the upper level (υ = 2) in the A²П_i state were derived by nonlinear least squares fitting.     

THz spectroscopy of H2D

The 2₁₂ − 1₁₁ line of H₂D⁺ at 2.363 THz that was detected toward Sgr B2 and identified based on a calculated line frequency has been measured in the laboratory precisely by using a tunable far-infrared spectrometer. All the available THz lines and known millimeter- and submillimeter-wave lines together with the combination differences derived from the infrared transitions are fitted to the Watson effective Hamiltonian. A set of improved molecular constants are obtained.     

A statistical analysis of the wave numbers of triplet rovibronic transitions of the D2 molecule: II. An experimental study of “dubious” lines

The spectral lines whose identification and wave numbers were acknowledged to be dubious in a statistical analysis of all the experimental data on the triplet rovibronic transitions of the D₂ molecule published by now were studied. The capillary-arc discharge spectrum in a D₂-H₂ (9: 1) mixture was measured at p ≈ 6 torr and current density j ≈ 10 A/cm². The wave numbers of 123 lines (of a total of 138 dubious lines) situated in the spectral region accessible to us (430–730 nm) were determined. The error in wave numbers was ≈ 0.06 cm^?1 because of the low intensity of the lines under study and overlap of their contours resulting from fortuitous superpositions of closely lying lines of other band systems (the so-called blending effect). The new wave number values were substantially different from the literature data. These differences were largely caused by random counting and blending errors and, in four instances, erroneous identification of lines in previous works.     

Study of (1, 4) band in the comet-tail (AΠi-XΣ) system of CO

Ro-vibrational spectrum of the (1, 4) band in the comet-tail system of CO⁺ cation is observed employing the optical heterodyne and magnetic rotation enhanced velocity modulation spectroscopy in the range of 13 189-13 472 cm⁻¹. Two hundred and eighteen spectral lines are assigned to 12 branches of this band for the first time, thus, precise molecular constants of the levels involved are obtained by nonlinear least-squares fitting procedure combining with our previous spectrum of the (1, 2) band.     

Rotational analysis of the (4, 8) band in the A-X system of Cl2

Thirty-four rovibronic spectral lines of the Ω=1/2 component of the (4, 8) band in the A-X system of ³⁵Cl₂⁺ were observed in the range of 16,940-17,010 cm⁻¹, employing optical heterodyne-enhanced velocity modulation spectroscopy. Nonlinear least-squares fitting the effective Hamiltonians results in precise band origin and other molecular constants of the levels involved.     

Calculation of spectroscopic constants and radiative parameters for A1Σ u+ -X1Σ g+ and B1Πu-X1Σ g+ electronic transitions of sodium dimer

Vibrational, rotational, and centrifugal spectroscopic constants and radiative parameters, i.e., the Einstein coefficients, oscillator strengths, and wave numbers for vibrational transitions in electronic systems of bands A ¹Σ _u ⁺-X ¹Σ _g ⁺ (0 ≤ v′ ≤ 25; 0 ≤ v″ ≤ 44), B ¹Π _u -X ¹Σ _g ⁺ (0 ≤ v′ ≤ 29; 0 ≤ v″ ≤ 47), and the radiative lifetimes for the vibrational levels of excited states of the sodium dimer, are calculated. The calculations are carried out based on semiempirical potential curves constructed in this study. The calculated spectroscopic constants and radiative lifetimes are compared to the experimental values.     

ArH+基态的势能函数与光谱常数

采用（QCISD(T)/Aug-CC-pVTZ方法计算优化了ArH⁺离子基态X¹∑⁺的离子结构和离解能.并用最小二乘法拟合Murrell-Sorbie函数得出相应的势能函数表达方式,由此计算的振转常数与实验光谱数据符合得很好. 关键词： +')" href="#">ArH⁺ Murrell-Sorbie函数 势能函数     

Ar+17和 Ar+16谱线的电子碰撞展宽

利用修改后伦敦理工大学的UCL扭曲波程序, 本文计算了自由电子与原子或离子的碰撞反应矩阵, 以此得到它的散射矩阵和碰撞强度.利用碰撞强度, 研究电子碰撞对辐射谱线影响.具体地, 以Ar⁺¹⁷和Ar⁺¹⁶的α线和β线为例, 计算了不同电子温度和密度下谱线的展宽和位移.     

P-branch emission spectra of the A1Π-X1Σ+ system of IrN

The P-branch emission spectra of (4,1) and (3,1) bands of the A¹Π-X¹Σ⁺ system of IrN molecule are studied using an analytical formula which is derived from elementary expression of molecular total energy by taking multiple spectral differences. It not only reproduces the known experimental transition lines, but also predicts the unknown spectral lines up to J= 80 for each band by using a group of fifteen known experimental transition lines.     

Ab initio study of spectroscopic properties of the calcium hydride molecular ion

In the present work, all adiabatic potential energy curves, spectroscopic constants and dipole moments of CaH⁺ molecular ion dissociating below the ionic limit Ca²⁺H⁻ are presented. These curves are determined by an ab initio approach involving a non-empirical pseudo-potential for the Ca core, core-valence correlation accounted in operator form with two types of core polarization potentials (CPP) and full valence Configuration Interaction. The molecule is thus treated as a two-electron system. The potential energy curves and the spectroscopic constants are presented. In addition, the permanent and transition dipole moments are calculated for most of the states and reveal the underlying ionic states. A rather good agreement with the available theoretical works in the literature is obtained for the spectroscopic constants of the lowest states of the CaH⁺ molecule.     

High resolution electronic band spectral studies of the GaI molecule

The emission band spectrum of the GaI molecule, lying in the region 3800–4200A and attributed to two overlapping transitions (A0⁺-X0⁺ and B1-X0⁺), has been studied under high resolution in the 3rd order of a 10.5 m Ebert grating spectrograph at a dispersion of 0.18/mm. Isotopic shifts of the ⁷¹GaI and ⁶⁹GaI molecules are calculated for various bands. They are found to agree with experimentally measured values, thereby confirming the vibrational assignments. The reversal of shading of various branches, belonging to one band and leading to the formation of extra heads, has been investigated. Making use of the rotational constants of the ground state (X0⁺) obtained from microwave spectral studies, the rotational constants of the excited A0⁺ and C1 states have been evaluated. Electronic configurations, potential energy curves and dissociation products are discussed.     

Linewidth studies on the Ar+ 476.5 nm and 480.6 nm lines excited in a helium-agron hollow cathode discharge

The spectral line shapes of the Ar⁺ 476.5 nm and 480.6 nm lines, excited in a He-Ar hollow cathode (HC) discharge, were measured using the Fabry-Perot technique. The collisional and Doppler linewidths were determined for the two lines. The collisional broadening constants are estimated to be (5±3) MHz/mbar and (6±3) MHz/mbar, respectively. The temperature obtained from the two Ar ion transitions was found to be 260 K higher than that expected for the rest of the gas mixture from earlier measurements. The possibility is discussed, that this excess temperature is caused by Ar ions partially created in the HC discharge by charge transfer collisions with He ₂ ⁺ molecules.     

Emission spectroscopy of the A<Superscript>1</Superscript>Π–X<Superscript>1</Superscript>Σ<Superscript>+</Superscript> system of AlH

The high-resolution emission spectrum of the A¹ Π–X¹Σ⁺ transition of AlH was observed in the 18 000–25 000 cm^-1 spectral region using a conventional spectroscopic technique. The AlH molecules were excited in an Al hollow-cathode lamp filled with a mixture of Ne carried gas and a trace amount of NH₃. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. In total 163 transition wave numbers belonging to six bands (0-0,1 and 1-0,1,2,3) were precisely measured and rotationally analysed. In the final fit the present data have been combined with available high-resolution measurements of the vibration-rotation bands by White et al. [J. Chem. Phys. 99, 8371 (1993)]. This procedure enabled extracting molecular constants for the A¹ Π and X¹ Σ⁺ states of AlH. A very slight local perturbation has been discovered in the v=1 vibration level of the A¹ Π state at J=5. This was probably caused by the interaction with the a³Π state.     

Role of neon in a decaying high-purity helium plasma

The evolution of the electron and atomic and molecular metastable densities and the radiation of the decaying plasma of helium with a 10^–5-fraction of neon additive is experimentally studied. A model of elementary processes in He–Ne plasma is constructed, which describes the formation and destruction of HeNe⁺ and Ne₂ ⁺ molecular ions and their contribution to the formation of the afterglow spectrum by the electronion recombination. The various criteria influence of neon on the parameters of the decaying plasma are studied. The possibility of determining the amount of neon in helium by measuring the relative intensities of helium molecular bands and neon spectral lines in the afterglow is considered.     

Electron spin resonance identification of phosphorus-centred radicals in γ-irradiated dialkyl phosphites

Potential curves have been calculated by the ab initio MRD CI method for states of OH⁺ correlating with O(³ P, ¹ D, ¹ S) + H⁺ and O⁺(⁴ S, ² D, ² P) + H. Spectroscopic constants derived from the calculated potential curves are in good agreement with the available experimental data. The calculations support the experimental assignment of vibrational quantum numbers for levels perturbing the A ³Π state.     

Hyperfine Interaction Constants of the HCCS and DCCS Radicals Studied by Fourier Transform Millimeter-Wave Spectroscopy

The rotational spectral lines of HCCS and DCCS have been observed with a Fourier transform millimeter-wave spectrometer in combination with a pulsed discharge nozzle. The HCCS radical is produced by discharging a mixture of C₂H₂ and CS₂ diluted in Ar. The DCCS radical is produced by using C₂D₂ instead of C₂H₂. The spectral lines of HCCS and DCCS in both the ²Π_3/2 and ²Π_1/2 states are measured in the frequency range from 16 to 48 GHz, and the molecular constants are determined accurately from a joint least-squares analysis with the reported millimeter- and submillimeter-wave data. The hyperfine interaction constants of the hydrogen and deuterium nuclei are determined for the first time, and are discussed in relation to the Renner-Teller effect on this molecule.     

NO分子b4Σ--a4Πi(4,0)带的吸收光谱

通过对NO与He流动混合气体放电, 产生了激发态的NO(a⁴Π_ii) 分子. 利用光外差-浓度调制吸收光谱技术测量了NO分子在12530-12850 cm^-1波段内的吸收光谱, 并标识出b⁴Σ^--a⁴Π_i(4,0)带在该波段内的324条光谱跃迁谱线. 采用标准⁴Σ^--⁴Π_i哈密顿量模型, 通过非线性最小二乘法拟合其中267条谱线, 拟合残差(0.0071 cm^-1) 接近实验系统测量误差(0.007 cm^-1). 获得的主要分子常数与文献提供的常数符合, 并且拟合得到了精细结构分子常数.     

The absorption spectrum of the (1, 0), (3, 1) and (4, 2) bands in the cΣg–aΣu system of He2 eximer

The near-infrared absorption spectrum of He₂ has been recorded in the range of 12 090–13 300 cm⁻¹ using the optical heterodyne concentration modulation spectroscopy. Fifty-nine He₂ spectral lines were assigned to the (1, 0), (2, 0), (3, 1) and (4, 2) bands in the c³Σ_g⁺–a³Σ_u⁺ system and a non-linear least-squares fitting was performed to get the improved molecular constants for the levels (υ = 1, 3 and 4) in the upper electronic state.