Dunham Constants Research Articles

Intracavity laser spectroscopy with Fourier-transform detection of tungsten sulfide, WS: Analysis of the (1,0) band of the [13.10] Ω = 1 − X3Σ–0+ transition

The (1,0) band of the [13.10] Ω = 1 − X3Σ–0+ transition of WS has been observed and recorded at Doppler-limited resolution using intracavity laser absorption spectroscopy detected with a Fourier-transform spectrometer (ILS–FTS). The tungsten sulfide molecules were produced in the plasma discharge formed when 0.35 A of RF current were applied to a W-lined Cu hollow cathode in an atmosphere that was 0.1% CS2, ~30% H2, and ~70% Ar at a total pressure of 1 torr. The hollow cathode was located within the resonator cavity of a tunable Ti:Sapphire laser, causing molecular absorption to be superimposed upon the broadband profile of the laser. This profile was detected using a Bruker IFS 125 M spectrometer using an instrument resolution of 0.01 cm−1. The ILS-FTS spectrum was analyzed using PGOPHER. Experimental line positions from the laser induced fluorescence (LIF) spectrum of WS [Tsang et al., J. Mol. Spec., 359, 31 (2019)] were included in the fit, and a limited Dunham model was built in PGOPHER to characterize the X 3Σ–0+ ground state of WS. The rotational coverage of the ground state is expanded from 0 < J < 35 to 0 < J < 62, the uncertainty in the ground state constants for WS are reduced by a factor of three, and a potential energy curve for that state is produced from the Dunham constants using the RKR method.

High temperature infrared spectrum of sodium iodide (NaI)

The absorption spectrum of sodium iodide vapor between 200 and 275cm−1 has been measured with a resolution of 0.006cm−1 at a temperature of 1096K. The Δv=1 transitions from v=1←0 to v=13←12 have been measured. Dunham constants are given from an least-squares analysis of 1285 fairly well resolved transitions. The band center for the fundamental band is ν0=257.2837±0.0002cm−1. The relative intensities of the Δv=1 transitions from different vibrational states are studied and it is shown that the intensity is roughly proportional to v″+1 as expected from the harmonic oscillator approximation. From measurements of the Herman–Wallis constant, α1,0=−0.0054±0.0008, it is estimated that the transition moment must be μ1,0≈0.135±0.020debye.

Determination of dunham coefficients and calculation of the energies of highly excited vibrational-rotational levels of the carbon monoxide molecule in the electronic ground state

The values of Dunham constants are calculated for the electronic ground state of the carbon monoxide molecule on the basis of new values of the effective rotational and centrifugal constants and the energies of the high vibrational-rotational states are predicted. The peculiarity of the approach consists in the use of vibrational-rotational levels computed according to the traditional polynomial equation of energy values as the initial data for the procedure of Dunham coefficients determination. The role of the maximum degree of the Dunham polynom in determining its coefficients is analyzed, and the energy levels up to ν = 40 and J = 60 are calculated. A comparison with the literature data is made.

Characterization of the outer well of NaH C 1Σ + state by fluorescence depletion spectroscopy

The outer well of the NaH C 1Σ + excited state was determined using pulsed optical–optical double resonance fluorescence depletion spectroscopy. The level-selected fluorescence of the A 1Σ + state is depleted back to the ground state when a probe laser excites the molecules to the C 1Σ + state. A total of 456 rovibrational levels, v = 5–33 and J = 1–11, were observed. A set of Dunham constants and the Rydberg–Klein–Rees (RKR) potential curve for the outer well were reported.

Infrared and near infrared emission spectra of SbH and SbD

The X 3Σ − ground state vibration–rotation spectrum of SbH and the near infrared spectra of the b 1Σ +– X 3Σ − transitions of SbH and SbD have been measured at high resolution by Fourier transform spectroscopy. The SbH and SbD radicals were generated in a tube furnace with a D.C. discharge of a flowing mixture of argon, hydrogen (or deuterium), and antimony vapor. In the infrared region, the 1–0 and 2–1 bands of the three components (0 +, 1 e , and 1 f ) as well as the 0 + component of the 3–2 band were observed for 121SbH and 123SbH. In the near infrared region, the 0–0, 1–1, and 2–2 bands of the b 1Σ +– X 3Σ − system of both SbH and SbD as well as the 3–3 band of SbD were observed. Except for a few lines, the antimony isotopic shift was not resolved for these electronic spectra. The present data set was combined with the available ground state data on SbD and a 1Δ data for SbH and SbD from previous work, and a least-squares fit was performed for each of the four isotopologues: 121SbH, 123SbH, 121SbD, and 123SbD. Improved spectroscopic constants were obtained for the observed vibrational levels of the X 3Σ −, a 1Δ, and b 1Σ + states of these four isotopologues. In addition, all the above data were also fitted simultaneously to a multi-isotopologue Dunham model, which yielded Dunham constants and Born–Oppenheimer breakdown parameters for these three electronic states. Interestingly, we found that Born–Oppenheimer breakdown corrections were also required for some of the spin–spin and spin–rotation parameters of the X 3Σ − state.

New Fourier transform infrared emission spectra of CaH and SrH: combined isotopomer analyses with CaD and SrD

In a search for the infrared spectra of gaseous CaH2 and SrH2, we obtained new Fourier transform infrared emission spectra of CaH and SrH, but no evidence of the metal dihydrides. The vibration-rotation bands from v=1→0 to v=4→3 of 40CaH and 88SrH, and the v=1→0 band of 87SrH and 86SrH were observed in the X2Σ+ ground electronic states. The new data were combined with the previous ground state data, obtained from diode laser infrared and pure rotational spectra, and the spectroscopic constants for v=0 to 4 of 40CaH and 88SrH were determined. In addition, the Dunham constants and the Born–Oppenheimer breakdown correction parameters were obtained using the previous ground state data for CaD and SrD in combined isotopomer fits. The equilibrium vibrational constants (ωe) for CaH and SrH were found to be 1298.400(1) and 1207.035(1) cm−1, respectively, while the equilibrium rotational constants (Be) are 4.277043(4) and 3.673495(4) cm−1. The equilibrium bond distances (re) were determined to be 2.0023603(9) Å for CaH and 2.1460574(10) Å for SrH.

Fourier transform infrared emission spectra of MgH and MgD.

High resolution Fourier transform infrared emission spectra of MgH and MgD have been recorded. The molecules were generated in an emission source that combines an electrical discharge with a high temperature furnace. Several vibration-rotation bands were observed for all six isotopomers in the X (2)Sigma(+) ground electronic state: v=1-->0 to 4-->3 for (24)MgH, v=1-->0 to 3-->2 for (25)MgH and (26)MgH, v=1-->0 to 5-->4 for (24)MgD, v=1-->0 to 4-->3 for (25)MgD and (26)MgD. The new data were combined with the previous ground state data, obtained from diode laser vibration-rotation measurements and pure rotation spectra, and spectroscopic constants were determined for the v=0 to 4 levels of (24)MgH and the v=0 to 5 levels of (24)MgD. In addition, Dunham constants and Born-Oppenheimer breakdown correction parameters were obtained in a combined fit of the six isotopomers. The equilibrium vibrational constants (omega(e)) for (24)MgH and (24)MgD were found to be 1492.776(7) cm(-1) and 1077.298(5) cm(-1), respectively, while the equilibrium rotational constants (B(e)) are 5.825 523(8) cm(-1) and 3.034 344(4) cm(-1). The associated equilibrium bond distances (r(e)) were determined to be 1.729 721(1) A for (24)MgH and 1.729 157(1) A for (24)MgD.

New Fourier transform infrared emission spectra of CaH and SrH: combined isotopomer analyses with CaD and SrD

In a search for the infrared spectra of gaseous CaH 2 and SrH 2, we obtained new Fourier transform infrared emission spectra of CaH and SrH, but no evidence of the metal dihydrides. The vibration-rotation bands from v=1→0 to v=4→3 of 40CaH and 88SrH, and the v=1→0 band of 87SrH and 86SrH were observed in the X 2 Σ + ground electronic states. The new data were combined with the previous ground state data, obtained from diode laser infrared and pure rotational spectra, and the spectroscopic constants for v=0 to 4 of 40CaH and 88SrH were determined. In addition, the Dunham constants and the Born–Oppenheimer breakdown correction parameters were obtained using the previous ground state data for CaD and SrD in combined isotopomer fits. The equilibrium vibrational constants ( ω e) for CaH and SrH were found to be 1298.400(1) and 1207.035(1) cm −1, respectively, while the equilibrium rotational constants ( B e) are 4.277043(4) and 3.673495(4) cm −1. The equilibrium bond distances ( r e) were determined to be 2.0023603(9) Å for CaH and 2.1460574(10) Å for SrH.

Infrared emission spectra of BeH and BeD

High resolution infrared emission spectra of beryllium monohydride and monodeuteride have been recorded. The molecules were generated in a furnace-discharge source, at 1500 °C and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases. Approximately 160 BeH lines and 167 BeD lines for the vibrational bands v=1→0 to v=4→3 were observed in the spectra and spectroscopic constants were determined. The Dunham constants (Yl,m) and Born–Oppenheimer breakdown constants were obtained in a combined fit of the BeH and BeD data. The equilibrium rotational constants (Be) for BeH and BeD were found to be 10.319 59(3) cm−1 and 5.688 29(2) cm−1, respectively, while the equilibrium vibrational constants (ωe) are 2061.416(3) and 1529.956(3) cm−1. The equilibrium distance (Re) was determined to be 1.342 436(2) Å for BeH.

Experimental Study of the NaK 31Π State

We report the results of an optical–optical double resonance experiment to determine the NaK 31Π state potential energy curve. In the first step, a narrow band cw dye laser (PUMP) is tuned to line center of a particular 2(A)1Σ+(v′,J′) ← 1(X)1Σ+(v",J") transition, and its frequency is then fixed. A second narrowband tunable cw Ti:Sapphirelaser (PROBE) is then scanned, while 31Π → 1(X)1Σ+violet fluorescence is monitored. The Doppler-free signals accurately map the 31Π(v,J) ro-vibrational energy levels. These energy levels are then fit to a Dunham expansion to provide a set of molecular constants. The Dunham constants, in turn, are used to construct an RKR potential curve. Resolved 31Π(v,J) → 1(X)1Σ+(v",J") fluorescence scans are also recorded with both PUMP and PROBE laser frequencies fixed. Comparison between observed and calculated Franck–Condon factors is used to determine the absolute vibrational numbering of the 31Π state levels and to determine the variation of the 31Π → 1(X)1Σ+transitiondipole moment with internuclear separation. The recent theoretical calculation of the NaK 31Π state potential reported by Magnier and Millié (1996,Phys. Rev. A54, 204) is in excellent agreement with the present experimental RKR curve.

Infrared Absorption and Emission Spectra of SiO

view Abstract Citations (29) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Infrared Absorption and Emission Spectra of SiO Campbell, J. M. ; Klapstein, D. ; Dulick, M. ; Bernath, P. F. ; Wallace, L. Abstract High-resolution Fourier transform infrared spectra of SiO were recorded from two sources, the umbral region of a sunspot and a high-temperature laboratory cell. Rovibrational transitions in the sunspot absorption spectrum were measured in consecutive vibrational bands from (1, 0) to (13, 12) with J values as high as 141 for 28Si 16O (1258 lines) and (1, 0) to (6, 5) for 29Si 16O and 30Si 16 O(455lines). In the lower temperature laboratory emission spectrum only 387 rotational lines in the (1, 0) to (5, 4) bands were measured exclusively for 28Si 16O. The laboratory spectrum served primarily to calibrate the lines in the sunspot spectrum to absolute rest frequencies. An improved set of Dunham constants for the 1Σ+ ground state was obtained from a global fit of a combined data set consisting of our IR data and all the previously reported microwave and millimeter-wave data. In addition an internuclear potential for the 1Σ+ ground state, in the form of a parameterized modified-Morse function, was also obtained by fitting the data directly to the eigenvalues of the radial Schrödinger equation. Publication: The Astrophysical Journal Supplement Series Pub Date: November 1995 DOI: 10.1086/192238 Bibcode: 1995ApJS..101..237C Keywords: MOLECULAR DATA; LINE: IDENTIFICATION full text sources ADS |

High-Resolution Fourier Transform Infrared Emission Spectra of Barium Monofluoride

The high-resolution infrared emission spectra of gas-phase barium monofluoride have been observed by Fourier transform spectrometry. Vibration-rotation bands were analyzed for the three most abundant isotopomers (138BaF, from 1-0 to 12-11; 137BaF, from 1-0 to 5-4; 136BaF, from 1-0 to 4-3) of the ground X2Σ+ state. The Dunham coefficients, Ylm, have been derived for all three isotopomers by fitting about 1750 lines for 138BaF, about 270 lines for 137BaF, and about 70 lines for 136BaF to the traditional Dunham model. In addition, the mass-reduced Dunham constants, Ulm, have been calculated from a global least-squares fit.

Infrared Emission Spectroscopy of Bismuth Monohydride and Bismuth Monodeuteride

The high-resolution infrared emission spectra of bismuth monohydride and bismuth monodeuteride have been observed by Fourier transform spectroscopy. Gaseous BiH and BiD were produced by the direct reaction of the metal with hydrogen and deuterium, respectively. About 120 lines with v = 1 → 0 to v = 3 → 2 for each isotopomer have been measured. Dunham coefficients, Y ij , have been derived in separate fits for the two molecules. In addition all data have been used in a combined fit to yield the mass-reduced Dunham constants, U ij .

High resolution vibration-rotation emission spectroscopy of BaH

The high resolution infrared emission spectrum of barium monohydride was recorded. The fundamental and two hot band transitions were measured for the main isotopic species 138BaH, and the fundamental band was measured for the minor isotopic species 137BaH, 136BaH, and 135BaH. Improved Dunham constants were determined for all four isotopomers. The sensitivity of the infrared emission technique was demonstrated by the improved accuracy of the Dunham constants.

Infrared spectrum of thallium chloride at 450°C

Abstract The high-resolution spectrum of the 283 cm −1 fundamental band of thallium chloride has been measured in the gas phase at a temperature of 450°C. The Δ v = 1 transitions of 205 Tl 35 Cl have been identified for transitions coming from the six lowest vibrational states. Many transitions also have been identified for the molecules 203 Tl 35 Cl and 205 Tl 37 Cl. Dunham constants are given for all four isotopic species of thallium chloride. As expected, the Born-Oppenheimer vibrational correction term for the thallium atom is found to be unusually large and negative.

ChemInform Abstract: The Millimeter‐ and Submillimeter‐Wave Spectrum of Boron Monofluoride: Equilibrium Structure

Abstract Utilizing a dc discharge absorption cell the millimeter and submillimeter-wave spectra of 11BF and 10BF have been observed in the v = 0, 1, 2 and v = 0, 1 vibrational states, respectively. The Dunham constants of the two isotopomers and the boron electric nuclear quadrupole coupling constant as well as the spin-rotation interaction constant of boron and fluorine have been determined. By removing from the Y01 Dunham constant the contributions due to the breakdown of the Born-Oppenheimer approximation, the resulting equilibrium bond distance is r e = 1.262672(7) A .

The millimeter and submillimeter-wave spectrum of boron monofluoride: Equilibrium structure

Utilizing a dc discharge absorption cell the millimeter and submillimeter-wave spectra of 11BF and 10BF have been observed in the v = 0, 1, 2 and v = 0, 1 vibrational states, respectively. The Dunham constants of the two isotopomers and the boron electric nuclear quadrupole coupling constant as well as the spin-rotation interaction constant of boron and fluorine have been determined. By removing from the Y 01 Dunham constant the contributions due to the breakdown of the Born-Oppenheimer approximation, the resulting equilibrium bond distance is r e = 1.262672(7) A ̊ .

Dunham coefficients of 14N2 from CARS measurements of high vibrational states in a low‐pressure discharge

AbstractSpectroscopic constants of the X 1Σg+ ground state of 14N2 are deduced from CARS spectra recorded in a 4 Torr d.c. N2 glow discharge. Vibrational states up to ν = 14 have been observed but only the 11 lower levels which have a good signal‐to‐noise ratio have been processed. The Dunham constants that were deduced yield vibrational band centre positions in good agreement with those of Lofthus and Krupenie.

The lowest rotational transition of several isotopic forms of KrD+

The J=0–1 absorption line of KrD+ has been observed for all six stable krypton isotopes in a dc glow discharge in Kr–D2 mixtures. For 83KrD+ the quadrupole coupling constant [eQq=549.1(5) MHz] and nuclear magnetic coupling constant [CN=−0.022(2) MHz] were determined. By combining the new microwave data for KrD+ with very precise published Dunham constants for KrH+ from Johns’ high resolution infrared spectral data, the mass independent Dunham parameters U01, ΔH01, and ΔKr01 were deduced. Precise Doppler shift measurements indicated a small drift velocity in the magnetic field enhanced, abnormal discharge in the direction opposite to that naively expected from the electrode polarity.

The vibrational energy spectrum of the 2 1Σ g+ state of Li 2

We calculate the vibrational energy levels for all three possible isotopic species of the 2 1Σ g + state of Li 2 and from them deduce a set of Dunham constants. Since the 2 1Σ g + state has substantial ionic character, its shape is usual and so is the spacing of its vibrational levels. We find for 7Li 2, Y 10 = 123.76 cm −1 and Y 20 = 1.87 cm −1, for example.