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Thirteen bands for the B¹Δg-A¹Πu system and eleven bands for the B'¹Σg+-A¹Πu system of C2 were identified in the Fourier transform infrared emission spectra of hydrocarbon discharges. The B'¹Σg+ v = 4 and the B¹Δg v = 6, 7, and 8 vibrational levels involved in nine bands were studied for the first time. A direct global analysis with Dunham parameters was carried out satisfactorily for the B¹Δg-A¹Πu system except for a small perturbation in the B¹Δg v = 6 level. The calculated rovibrational term energies up to B¹Δg v = 12 showed that the level crossing between the B¹Δg and d³Πg states is responsible for many of the prominent perturbations in the Swan system observed previously. Nineteen forbidden transitions of the B¹Δg-a3?u transition were identified and the off-diagonal spin-orbit interaction constant AdB between d³Πg and B¹Δg was derived as 8.3(1) cm-1. For the B'¹Σg+-A¹Πu system, only individual band analyses for each vibrational level in the B'¹Σg+ state could be done satisfactorily and Dunham parameters obtained from these effective parameters showed that the anharmonic vibrational constant wexe is anomalously small (nearly zero). Inspection of the RKR (Rydberg-Klein-Rees) potential curves for the B'¹Σg+ and X¹Σg+ states revealed that an avoided crossing or nearly avoided crossing may occur around 30 000 cm-1, which is responsible for the anomalous molecular constants in these two states. [ABSTRACT FROM AUTHOR]

Deperturbation analysis of the A 2Π → X 2Σ+ and B′ 2Σ+ → X 2Σ+ emission spectra of 24MgH is reported. Spectroscopic data for the v = 0 to 3 levels of the A 2Π state and the v = 0 to 4 levels of the B′ 2Σ+ state were fitted together using a single Hamiltonian matrix that includes 2Π and 2Σ+ matrix elements, as well as off-diagonal elements coupling several vibrational levels of the two states. A Dunham-type fit was performed and the resulting Yl,0 and Yl,1 coefficients were used to generate Rydberg-Klein-Rees (RKR) potential curves for the A 2Π and the B′ 2Σ+ states. Vibrational overlap integrals were computed from the RKR potentials, and the off-diagonal matrix elements coupling the electronic wavefunctions (a+ and b) were determined. Zero point dissociation energies (D0) of the A 2Π and B′ 2Σ+ states of 24MgH were determined to be 12 957.5 ± 0.5 and 10 133.6 ± 0.5 cm-1, respectively. Using the Y0,1 coefficients, the equilibrium internuclear distances (re) of the A 2Π and B′ 2Σ+ states were determined to be 1.67827(1) Å and 2.59404(4) Å, respectively. [ABSTRACT FROM AUTHOR]

Fourier transform emission spectra of D[sub 2]O vapor were recorded at a temperature of 1500 °C in the wavenumber range 380–1880 cm[sup -1]. 15 346 lines were measured, of which the majority were identified as belonging to D[sub 2]O. The spectrum was analyzed using variational nuclear motion calculations based on spectroscopically determined potential-energy surfaces. Initial assignments were made using a potential surface obtained by fitting a high accuracy ab initio potential. The new assignments were used to refine the potential surface, resulting in additional assignments. A total of 6400 D[sub 2]O transitions were assigned and 2144 new D[sub 2]O energy levels were obtained. Transitions involving the 4ν[sub 2] and 5ν[sub 2] bending states, with band origins of 4589.30 (±0.02) and 5679.6 (±0.1) cm[sup -1], respectively, were assigned for the first time.© 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

High resolution, near infrared emission spectra of TiH and TiD have been recorded with a Fourier transform spectrometer. The TiH and TiD molecules were made in a titanium hollow cathode lamp operated with a mixture of neon and hydrogen or deuterium gases. A heavily perturbed band system near 938 nm is assigned as a [sup 4]Φ-X[sup 4]Φ electronic transition. Line positions and approximate spectroscopic constants are reported for the 0-0 band of the new transition. The 4Φ-X[sup 4]Φ TiH transition might potentially be observed in late M-type stars and in L-type brown dwarfs. [ABSTRACT FROM AUTHOR]

The molecular potential energy function and electronic dipole moment function for the ground state of CaF were studied with MRCI, ACPF, and RCCSD(T) ab initio calculations. The RCCSD(T) potential function reproduces the experimental vibrational intervals to within ∼2 cm −1 . The RCCSD(T) dipole moment at the equilibrium internuclear separation agrees well with the experimental value. Over a wide range of internuclear separations, far beyond the range associated with the observed spectra, the ab initio dipole moment functions are similar and highly linear. An extended Morse oscillator (EMO) potential function was also obtained by fitting the observed lines of the laboratory vibration-rotation and pure rotation spectra of the 40 CaF X 2 Σ + ground state. The fitted potential reproduces the observed transitions ( v  ≤ 8, N  ≤ 121, Δ v  = 0, 1) within their experimental uncertainties. With this EMO potential and the RCCSD(T) dipole moment function, line lists for 40 CaF, 42 CaF, 43 CaF, 44 CaF, 46 CaF, and 48 CaF were computed for v  ≤ 10, N  ≤ 121, Δ v  = 0–10. The calculated emission spectra are in good agreement with an observed laboratory spectrum of CaF at a sample temperature of 1873 K. [ABSTRACT FROM AUTHOR]

An extended Morse oscillator (EMO) potential function was obtained by fitting the observed laboratory vibration-rotation and pure rotational spectra of the 24 MgF X 2 Σ + ground state. The fitted potential reproduces the observed transitions within the observation uncertainties. With this EMO potential and an analytic dipole moment function in the form of a Padé approximant fitted using ab initio dipole moment data, line lists for 24 MgF, 25 MgF and 26 MgF were computed for v≤8, N≤100, Δv=0–8. It was discovered that directly using the ab initio dipole moment points with cubic spline interpolation to calculate line intensities worked for Δv<3, but failed for higher Δv values. A simple solution was found by fitting the ab initio dipole points with a suitable analytical dipole moment function. The calculated emission spectra are in good agreement with an observed laboratory spectrum with the MgF sample at 1823 K. [ABSTRACT FROM AUTHOR]

We present line lists for ammonia (NH3) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for 12 temperatures (300°C-1300°C in 100°C intervals and 1370°C) and each line list covers the 740-2100 cm-1 range, which includes the majority of the ν2 umbrella bending mode region (11 μm) and the ν4 asymmetric bending mode region (6.2 μm). We also demonstrate the useful technique of obtaining empirical lower state energies from a set of spectra recorded at different sample temperatures. Using our NH3 spectra, we have estimated lower state energies (E Low in cm-1) and our values have been incorporated into the line lists along with calibrated wavenumbers (˜ν in cm-1) and calibrated line intensities (S' in cm molecule-1) for each line. We expect our hot NH3 line lists to find direct application in the modeling of planetary atmospheres and brown dwarfs. [ABSTRACT FROM AUTHOR]

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In two previous papers on the infrared emission spectra of gaseous BeH2, BeD2, and MgH2 molecules, we reported rotational analyses of the antisymmetric stretching fundamental band and several hot bands. The problems in the ℓ-type resonance fits of BeH2 and MgH2 have now been resolved, and the results are reported in this Note. [ABSTRACT FROM AUTHOR]

In two previous papers on the infrared emission spectra of gaseous BeH2, BeD2, and MgH2 molecules, we reported rotational analyses of the antisymmetric stretching fundamental band and several hot bands. The problems in the ℓ-type resonance fits of BeH2 and MgH2 have now been resolved, and the results are reported in this Note. [ABSTRACT FROM AUTHOR]

Thirteen bands for the B¹Δg-A¹Πu system and eleven bands for the B'¹Σg+-A¹Πu system of C2 were identified in the Fourier transform infrared emission spectra of hydrocarbon discharges. The B'¹Σg+ v = 4 and the B¹Δg v = 6, 7, and 8 vibrational levels involved in nine bands were studied for the first time. A direct global analysis with Dunham parameters was carried out satisfactorily for the B¹Δg-A¹Πu system except for a small perturbation in the B¹Δg v = 6 level. The calculated rovibrational term energies up to B¹Δg v = 12 showed that the level crossing between the B¹Δg and d³Πg states is responsible for many of the prominent perturbations in the Swan system observed previously. Nineteen forbidden transitions of the B¹Δg-a3?u transition were identified and the off-diagonal spin-orbit interaction constant AdB between d³Πg and B¹Δg was derived as 8.3(1) cm-1. For the B'¹Σg+-A¹Πu system, only individual band analyses for each vibrational level in the B'¹Σg+ state could be done satisfactorily and Dunham parameters obtained from these effective parameters showed that the anharmonic vibrational constant wexe is anomalously small (nearly zero). Inspection of the RKR (Rydberg-Klein-Rees) potential curves for the B'¹Σg+ and X¹Σg+ states revealed that an avoided crossing or nearly avoided crossing may occur around 30 000 cm-1, which is responsible for the anomalous molecular constants in these two states. [ABSTRACT FROM AUTHOR]

The gaseous BeH[sub 2] molecule has been synthesized by means of an electrical discharge inside a high-temperature furnace and identified with infrared emission spectroscopy. The antisymmetric stretching mode v[sub 3] has been detected near 2179 reciprocal centimeters. The BeH[sub 2] molecule has a linear, symmetric structure with an r[sub o] Belt bond length of 1.333761(2) angstroms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Calcium hydride is among the most important diatomic molecules in astrophysics. [•] The A–X and B–X bands of CaH are found frequently in sunspots and cool stars. [•] We recorded high resolution emission spectra of the A2Π–X2Σ and B2Σ–X2Σ transitions of CaH. [•] Rotational analysis and deperturbation of the A2Π and B2Σ excited states have been carried out. [ABSTRACT FROM AUTHOR]

Abstract: Emission spectra of the A2Π→X2Σ+ and B2Σ+ →X2Σ+ transitions of CaD were produced in a discharge-furnace emission source and recorded with a high resolution Fourier transform spectrometer. The Δv =0 and Δv =−1 sequences up to v′ =3 of the A2Π state and v′ =2 of the B2Σ+ state have been observed and rotationally analyzed. Empirical band constants and Dunham-type constants were determined for all electronic states using N2 Hamiltonians. The equilibrium constants T e, ω e and ω e x e were determined to be 14407.604(2), 957.330(4) and 10.415(2)cm−1 for the A2Π state, and 15751.570(2), 925.840(4) and 12.417(2)cm−1 for the B2Σ+ state, respectively. The equilibrium bond lengths (r e) of the A2Π and B2Σ+ states are 1.977495(3) and 1.963467(6)Å, respectively. [Copyright &y& Elsevier]

Abstract: Emission spectra of WO have been observed in the 4000–35000cm−1 region using a Fourier transform spectrometer. Molecules were produced by exciting a mixture of WCl6 vapor and He in a microwave discharge lamp. A 3Σ− state has been assigned as the ground state of WO based on a rotational analysis of the observed bands and ab initio calculations. After rotational analysis, a majority of strong bands have been classified into three groups. Most of the transitions belonging to the first group have an Ω =0+ state as the lower state while the bands in the second group have an Ω′′=1 state as the lower state. These two lower states have been assigned as X0+ and X1 spin components of the X3Σ− ground state of WO. The third group consists of additional bands interconnected by common vibrational levels involving some very low-lying states. The spectroscopic properties of the low-lying electronic states have been predicted from ab initio calculations. The details of the rotational analysis are presented and an attempt has been made to explain the experimental observations in the light of the ab initio results. [Copyright &y& Elsevier]

Abstract: An emission spectrum of hot D2O (1500°C) has been analyzed in the 2077–4323cm−1 region. A considerable number of new vibration-rotation energy levels have been determined and two new vibrational levels identified. The new (041) and (022) vibrational levels have estimated band origins of 7343.93±0.01 and 7826.38±0.02cm−1, respectively. [Copyright &y& Elsevier]

Abstract: An emission spectrum recorded in an oxyacetylene torch [P.-F. Coheur, P.F. Bernath, M. Carleer, R. Colin, O.L. Polyansky, N.F. Zobov, S.V. Shirin, R.J. Barber, J. Tennyson, J. Chem. Phys. 122 (2005) 074307] is analyzed for the region covering stretching fundamentals and associated hot bands of water. Many lines could be assigned on the basis of previously determined energy levels. New assignments made with a new variational linelist allow a further 800 energy levels covering 15 vibrational states and rotations up to J =32 to be assigned. A simultaneous re-analysis of previously reported sunspot absorption spectra leads to the assignment of 581 further lines in the L-band spectrum and 67 in the N-band spectrum. [Copyright &y& Elsevier]

Abstract: The near-infrared emission spectrum of CoS has been recorded at a resolution of 0.04cm−1 using a Fourier transform spectrometer. Gas-phase CoS was produced by the reaction of cobalt vapor and CS2 vapor at about 3000K in a carbon tube furnace. Two electronic transitions were observed for the first time in the 3200–6000cm−1 region and have been assigned to the A 4Φ i –X 4Δ i and B 4Π i –X 4Δ i transitions. The 0–0 bands for all four sub-bands of the A 4Φ i –X 4Δ i transition, and the 0–0, 0–1, 1–0, and 1–1 bands for the 5/2–7/2 sub-band of the B 4Π i –X 4Δ i transition were rotationally analyzed. Combined with the previous microwave data from the literature, the present data were fitted using the usual Hund’s case (c) energy level expressions, and spectroscopic constants were obtained for the X 4Δ i , A 4Φ i , and B 4Π i states of CoS. A Hund’s case (a) fit was also carried out for the A 4Φ i –X 4Δ i transition. The presence of a low-lying 4Φ i state for both CoS and CoO was not anticipated based on previous experimental and theoretical work. [Copyright &y& Elsevier]

Abstract: New Fourier transform measurements for the A 2Π− X 2Σ+ system of BeH are combined with previously published A − X data for BeH, BeD, and BeT, with existing data for the C 2Σ+ − X 2Σ+ system, and with recent vibration–rotation data for BeH and BeD, and fitted using combined-isotopologue Dunham expansion and direct-potential-fit methods. This data set provides direct spectroscopic information spanning 95% of the ground X 2Σ+ state potential well, and provides the most comprehensive spectroscopic description of this state reported to date. The analysis of this data set allows us to study the breakdown of the Born–Oppenheimer approximation for a metal hydride from the minimum of the potential well to near the dissociation limit. Improved molecular constants are also determined for the A 2Π and C 2Σ+ states. [Copyright &y& Elsevier]

The gaseous MgD2 molecule has been synthesized for the first time in an electrical discharge inside a high-temperature furnace. The high-resolution infrared emission spectrum of MgD2 was recorded with a Fourier transform spectrometer, and the antisymmetric stretching mode (v3) was detected near 1176.5 cm–1. The v3 band was rotationally analyzed, and the r0 Mg—D bond distance was determined to be 1.700 874(8) Å. [ABSTRACT FROM AUTHOR]

This article presents a study on the vibration-rotation emission spectra of gaseous ZnH2 and ZnD2. These gases were discovered in an emission source that combines an electrical discharge with a high-temperature furnace. High-resolution infrared emission spectra of ZnH2 and ZnD2 have been recorded with a Fourier transform spectrometer. Metal hydrides are among the simplest inorganic molecules. They are favorite target molecules for ab initio quantum chemists because of the simplicity of metal-hydrogen bonding. Theoretical calculations can predict reliable molecular properties for metal hydrides because they have a relatively small number of electrons.