R.S. Ram

Fourier transform spectroscopy of the A3Π-X3Σ− transition of NH

Abstract The A3Π-X3Σ− transition of NH has been observed using a high-resolution Fourier transform spectrometer. The first three vibrational levels in each state were observed and the vibrational, fine structure, and rotational constants obtained.

Line Intensities and Molecular Opacities of the FeH F 4Δi-X 4Δi Transition

We calculate new line lists and opacities for the F 4 Di-X 4 Di transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots, and brown dwarfs. The new Einstein A-values for each line are based on a high-level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (Honl-London factors) are derived for both the Hunds case (a) and (b) coupling limits. A new set of spectroscopic constants was derived from the exist- ing FeH term values for v¼ 0, 1, and 2 levels of the X and F states. Using these constants, extrapolated term values were generated for v¼ 3 and 4 and for J-values up to 50.5. The line lists (including Einstein A-values) for the 25 vibrational bands with v� 4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were used to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507. Subject headings: infrared: stars — line: identification — molecular data — stars: atmospheres — stars: fundamental parameters — stars: low-mass, brown dwarfs

Fourier Transform Emission Spectroscopy of the Copper Dimer

Abstract The emission spectrum of gas-phase Cu 2 has been observed using a Fourier transform spectrometer. The molecule was produced in a Cu hollow cathode lamp operated with a flow of neon gas. The rotational structure of five bands (2-0, 1-0, 0-0, 0-1, 0-2, and 1-3) belonging to the B 1 Σ u + - X 1 Σ g + system of 63 Cu 2 , and 63 Cu 65 Cu was analyzed, providing improved molecular constants. The equilibrium molecular constants for the X 1 Σ g + state extracted from the observed data are ω e = 266.4594(29) cm −1 , ω e x e = 1.0350(16) cm −1 , and r e = 2.21927(3) A , while the corresponding values for the B 1 Σ u + state are ω e = 246.3170(24) cm −1 , ω e x e = 2.2310(8) cm −1 , and r e = 2.32811(3) A . There is evidence for a systematic global perturbation in the excited B 1 Σ u + state.

Fourier transform emission spectroscopy of ScN

The near‐infrared electronic emission spectrum of ScN has been observed in the 1.6–1.8 μm spectral region using a Fourier transform spectrometer. The three bands with origins at 5820.0944(5), 6051.2858(20), and 6266.1290(13) cm−1 have been assigned as the 0‐0, 1‐1, and 2‐2 bands of the A 1Σ+−X 1Σ+ electronic transition. The principal equilibrium molecular constants for the ground state obtained from a fit of the observed lines are B‘e=0.554 609(17) cm−1, r‘e=1.687 23(3) A and the corresponding values for the excited state are B’e=0.549 277(17) cm−1, re=1.695 40(3) A. Although ScN is a well‐known refractory solid, our work is the first observation of the gas‐phase ScN molecule.

The A 3Φ -X 3Δ System (γ Bands) of TiO: Laboratory and Sunspot Measurements

The spectrum of the A3Φ-X3Δ system of TiO has been measured in the laboratory as well as in sunspots. In the laboratory, the bands were excited in a hollow cathode lamp and were observed using a Fourier transform spectrometer. These bands were also identified in the spectrum of a sunspot umbra recorded with the same spectrometer. Both laboratory and solar measurements have been combined with jet-cooled laser measurements and pure rotational frequencies in the X3Δ ground state to obtain improved molecular constants for the A3Φ and X3Δ states of TiO. RKR potential energy curves and Franck-Condon factors were also calculated.

Fourier transform infrared emission spectroscopy and ab initio calculations on RuN

The emission spectrum of RuN has been observed in the near infrared using a Fourier transform spectrometer. RuN molecules were excited in a hollow cathode lamp operated with neon gas and a trace of nitrogen. Two bands with 0–0 Q heads near 7354 and 8079 cm−1 and a common lower state have been assigned as 2Π1/2–2Σ+ and 2Π3/2–2Σ+ subbands, respectively, of a C 2Π–X 2Σ+ transition. A rotational analysis of these bands has been performed and molecular constants have been extracted. The principal molecular constants for the ground X 2Σ+ state of the most abundant 102RuN isotopomer are: B0=0.552 782 9(70) cm−1, D0=5.515(13)×10−7 cm−1, γ0 =−0.044 432(22) cm−1 and r0=1.573 869(10) A. The excited C 2Π state has the following molecular constants: T00=7714.342 60(53) cm−1, A0=725.8064(11) cm−1, B0=0.516 843 4(80) cm−1, D0=5.685(16)×10−7 cm−1, p0=5.467(36)×10−3 cm−1 and r0=1.627 670(13) A. Ab initio calculations have been carried out on RuN to ascertain the nature of the experimentally observed states and to predict ...

Fourier Transform Emission Spectroscopy: The Vibration-Rotation Spectrum of CuH

The Fourier transform infrared emission spectrum of CuH was observed. The (I, 0), (2, I), and (2, 0) vibration-rotation bands of both %tH and %tH were recorded from a copper hollow-cathode discharge in neon and hydrogen. Improved molecular constants for the u = 0, I, and 2 levels of CuH are provided. This work is the first observation of a vibration-rotation spectrum of a metal hydride in emission. 0 1985 Academic press, IIIC.

SPECTROSCOPIC CONSTANTS, ABUNDANCES, AND OPACITIES OF THE TiH MOLECULE

Using previous measurements and quantum chemical calculations to derive the molecular properties of the TiH molecule, we obtain new values for its rovibrational constants, thermochemical data, spectral line lists, line strengths, and absorption opacities. Furthermore, we calculate the abundance of TiH in M and L dwarf atmospheres and conclude that it is much higher than previously thought. We find that the TiH/TiO ratio increases strongly with decreasing metallicity, and at high temperatures can exceed unity. We suggest that, particularly for subdwarf L and M dwarfs, spectral features of TiH near ~0.52 and 0.94 μm and in the H band may be more easily measurable than heretofore thought. The recent possible identification in the L subdwarf 2MASS J0532 of the 0.94 μm feature of TiH is in keeping with this expectation. We speculate that looking for TiH in other dwarfs and subdwarfs will shed light on the distinctive titanium chemistry of the atmospheres of substellar-mass objects and the dimmest stars.

Fourier transform emission spectroscopy of NeH

Abstract The Fourier transform emission spectrum of NeH + was observed. The (1, 0), (2, 1), and (3, 2) vibration-rotation bands of 20 NeH + ; the (1, 0) and (2, 1) bands of 20 NeD + ; and the (1, 0) band of 22 NeH + were recorded from a copper hollow-cathode discharge in neon and hydrogen. Molecular constants, including Born-Oppenheimer breakdown parameters, were extracted from the data.

The A 6Σ+-X 6Σ+ transition of CrH, Einstein coefficients, and an improved description of the A state

The spectrum of CrH has been reinvestigated in the 9000–15 000 cm−1 region using the Fourier transform spectrometer of the National Solar Observatory. The 1-0 and 1-1 bands of the A 6Σ+-X 6Σ+ transition have been measured and improved spectroscopic constants have been determined. A value for the 2-0 band origin has been obtained from the band head using estimated spectroscopic constants. These data provide a set of much improved equilibrium vibrational and rotational constants for the A 6Σ+ state. An accurate description of the A-X transition has been obtained using a multireference configuration interaction approach. The inclusion of both scalar relativity and Cr 3s3p correlation are required to obtain a good description of both states. The ab initio computed Einstein coefficients and radiative lifetimes are reported.