High-resolution Fourier transform spectroscopy of D2CO in the 8- to 12-μm region

The Coriolis-coupled ν₃ (1100 cm⁻¹), ν₆ (989 cm⁻¹), and ν₄ (938 cm⁻¹) fundamental bands of D₂CO have been recorded with a BOMEM Model DA 3.002 Fourier transform spectrometer at an apodized resolution of 0.004 cm⁻¹. A total of 3704 transitions have been assigned in the 780- to 1200-cm⁻¹ spectral region. Constants have been determined for terms up to P⁶ in centrifugal distortion and up to P³ in Coriolis interaction. These constants reproduce the observed spectra with residuals for well-resolved lines that are less than 0.0004 cm⁻¹, one-tenth of the resolution. Relative signs of the transition moments have been determined by comparison of observed and calculated relative intensities of perturbed transitions. Five new assignments for far-infrared laser lines pumped by CO₂ lasers have been obtained as a result of calculations based on the determined constants.     

Far infrared spectra of the D2 and the D2-He systems

The rototranslational absorption spectra of D₂ and D₂ - He at 92K have been measured at different densities and different D₂ concentrations. From these spectra we have derived the translational line-shape; the observed density effects and, in particular, the relevance of the two-body and the three-body contributions have been discussed by comparing the line-shape derived from the D₂ spectra with the two-body term obtained from the analysis of the D₂ - He spectra.     

Calculations and measurements of N2O absorption at high temperature in the 4.5 μm region

An approximate N₂O spectroscopic database suitable for high temperature and medium resolution applications has been created in the 4.5 μm region. Intensities of ¹⁴N₂ ¹⁶O hot bands have been extrapolated pragmatically from the v₃ band intensity and energies of vibrational levels have been computed by diagonalization of the effective Hamiltonian. The new parameters have been merged with the data available in the HITRAN database and in the recent experimental work of Toth. The entire list has then been used to generate individual line parameters. Pure N₂O spectra have been recorded with a Fourier Transform spectrometer up to 900 K and with 1 cm⁻¹ resolution. A good agreement between these spectra and line-by-line calculations using the new database is obtained while the use of HITRAN greatly underestimates absorption at high temperature.     

On the precision of calculations of initial state radiation in the LEP Z line-shape fits

Calculation of initial state radiation (ISR) in the fitting program MIZA and in the Standard Model program BHM is improved within the analysis of the Z line-shape measurements at LEP. The uncertainty on the determination of the Z line-shape parameters coming from the precision of ISR calculations is 2×10⁻⁴ on σ₀ and 0.1 MeV on m_Z and Γ_Z.     

Electron spectroscopy using excited atoms and photons IV. Penning ionization of ethylene

Using helium metastable atoms (2¹S, 2³S), the Penning ionization of C₂H₄ has been studied using a high resolution electrostatic electron analyzer. The Franck—Condon envelope for the ground state of C₂H₄⁺ (X²B_3u) is found to be the same for He* (2³S) Penning ionization and 584 Å photoionization. The ΔE shift values and the relative electronic transition probabilities are reported for four ionic states. Unusually large differences have been found for the relative electronic transition probabilities for Penning ionization and photoionization.     

High-resolution infrared spectrum of CH2D2: The ν9 fundamental band at 8 u̧m

The infrared spectrum of CH₂D₂ has been recorded between 1100 and 1360 cm^?1 with a SISAM-type spectrometer whose resolution limit is about 0.015 cm^?1 in our spectrum. Some lines have been identified as transitions of the ν₃ parallel band of CH₃D. The band center ν = 1236.2786 ± 0.0010 cm^?1 and a set of upper state constants was obtained for the ν₉ band of CH₂D₂. A perturbation was pointed out in ν₉; nevertheless, all frequencies have been fitted with a standard deviation of 3.8 × 10^?3 cm^?1.     

Analysis of the ν2 and ν4 infrared bands of CD4

The infrared spectrum of totally deuterated methane CD₄ has been recorded between 930 cm^?1 and 1180 cm^?1 under high resolution (0.003 cm^?1). The ν₂ and ν₄ bands of ¹²CD₄ have been reanalyzed on the basis of a complete third-order Hamiltonian including all the coupling terms linking the upper states of the two bands. A set of only 16 self-consistent parameters have been adjusted to fit more than 1650 assigned transitions reaching a maximum upper state J value of 20. The obtained standard deviation is 0.0041 cm^?1. In addition, 171 lines of the ν₄ band of ¹³CD₄ have been assigned. They have been analyzed, in the same dyad scheme, by adjusting 7 parameters of the ν₄ band together with the main ζ₂₄ Coriolis parameter. The obtained standard deviation is only 0.0012 cm^?1.     

High-resolution spectroscopy of the v2 = 2 a ← v2 = 1 s band of 15NH3

Twenty-four transitions of the v₂ = 2 a ← v₂ = 1 s hot band of ¹⁵NH₃ have been observed by an infrared microwave sideband laser spectrometer. In addition, 149 transitions of the band have been obtained by a Fourier transform spectrometer at a resolution of 0.02 cm⁻¹. A weighted least-squares analysis has been carried out and the rms deviation of the fit is 0.00097 cm⁻¹. It was necessary to include the Δ(K − l) = ±3 interaction between the v₂ = 2 a and the v₄ = a states in the analysis.     

Collision induced absorption spectra of the fundamental band of D2 in binary mixtures D2-Kr at 298 K

The enhancement spectrum of the collision induced absorption of D₂ in its fundamental band region 2600-4000 cm⁻¹ in binary mixtures D₂-Kr was studied at 298 K for base densities of D₂ in the range 9-20 amagat and for partial densities of Kr in the range 7-120 amagat. The binary absorption coefficient of the band has been determined from the measured integrated absorption coefficient and found to be 3.9 × 10⁻³ cm⁻² amagat⁻². An analysis of the experimental spectrum was carried out by assuming appropriate line-shape functions and the half-width parameters δ₁, δ₂, δ_d and δ_c of the long range quadrupole, and of the short range overlap induced transitions have been determined. Good agreement was obtained between the recorded spectrum of the fundamental band and the synthetic profile.     

High-resolution spectroscopy of the v2 = 2 a ← v2 = 1 s band of 14NH3

Twenty-one transitions of the v₂ = 2 a ← v₂ = 1 s hot band of ¹⁴NH₃ have been observed by an infrared microwave sideband laser spectrometer with an absolute accuracy of 0.00002 cm⁻¹. One hundred and seventeen transitions of the band have been obtained by a Fourier transform infrared spectrometer at a resolution of 0.005 cm⁻¹. A weighted least-squares analysis of these data has been carried out to yield 17 molecular parameters for the v₂ = 2 a state. These parameters reproduce the experimental frequencies with a root mean square deviation of 0.000123 cm⁻¹. To calculate the frequencies to this accuracy it was necessary to take into account the Δ(K − l) = ±3 interaction between the v₂ = 2 a and v₄ = 1 a states.     

Quantitative laboratory spectra and spectral line parameters for the v2 and v4 bands of PH3 applicable to spectral radiative models of the atmosphere of Jupiter

Quantitative laboratory PH₃ absorption spectra were obtained in the 800–1350 cm^-1 region, at ～0.05 cm^-1 resolution, with gas amounts corresponding to observed PH₃ absorptions in the atmosphere of Jupiter. A compilation of spectral line positions, intensities and ground state energies has been generated for the v₂ and v₄ bands of PH₃. Line-by-line calculations have been compared with the experimental spectra.     

The Stimulated Raman Spectrum of Cyanogen

The Raman spectrum of cyanogen¹²C₂¹⁴N₂has been investigated at nearly Doppler resolution by means of the Stimulated Raman technique. The regions around theQbranches of the ν₁(2330 cm⁻¹) and ν₂(845 cm⁻¹) vibrations have been recorded. Besides the fundamentals, hot bands arising fromv₅= 1,v₅= 2, andv₄= 1 have been observed. The spectra have been analyzed, and rotational constants for the excited states have been obtained. Computer simulations of the Raman contours have been carried out as a test of the assignments.     

Line-shape parameters of the Raman lines of chloro-, bromo-, and iodobenzene

High-resolution Raman spectra have been measured of chloro-, bromo-, and iodobenzene for line shifts up to 1600 cm⁻¹ and several new lines were resolved. The line-shape parameters and depolarization ratios of most of these lines are reported here for the first time. The 1595 cm⁻¹ benzene E_2g doublet was resolved into the A₁ and B₁ monohalogen substituted lines. In going from bromoto iodobenzene a reversal in the A₁-B₁ line intensities was observed.     

Far infrared absorption in normal H2 from 77 to 298 K

The translational-rotational absorption spectrum of normal H₂ has been measured from 80 to 900 cm^?1 at seven temperatures from 77.4 to 298 K. These results have been accurately fitted by a three-parameter line-shape function, thereby providing a reliable way of predicting the absorption of H₂ anywhere in this frequency and temperature region.     

The high-resolution infrared spectrum of HBF2: The 401 band near 926 cm−1

The type-C out-of-plane bending fundamental ν₄ (near 926 cm⁻¹) in the infrared spectrum of gaseous difluoroborane, HBF₂, has been recorded at high resolution. Rotational and centrifugal distortion constants have been obtained for the two isotopic species H¹⁰BF₂ and H¹¹BF₂ in both the ground and 4¹ levels. A small rotational perturbation in the 4¹ level of H¹¹BF₂ has allowed an estimate of the position of the ν₆ fundamental, which so far has not been observed directly.     

Disorder-induced Raman scattering of In1−xGaxP in the transverse acoustic phonon region

Raman scattering measurements have been performed on In_1?xGa_xP (0.62?x?1) over the entire frequency range of first and second order scattering. Besides the already known disorder activated band between the LO(Γ) and TO(Γ) modes a new disorder activated band is found in the region of transverse acoustic phonons around 87 cm^-1. The position of the new band shifts only slightly with composition while its strength and line-shape change.     

High-resolution infrared spectrum of CH2D2: The ν3 fundamental band at 7 μm

The infrared spectrum of CH₂D₂ has been recorded in the region of 1345 to 1561 cm^?1 with a resolution of 0.030 to 0.026 cm^?1. Most of the observed lines have been assigned to transitions of the ν₃ band of CH₂D₂. However, 114 lines have been identified as transitions of the ν₂ band of H₂¹⁶O whose band origin has been directly determined to be 1594.7472 ± 0.0030 cm^?1. A few weak lines, probably belonging to the ν₅ fundamental of CH₂D₂, remain unassigned. The band center ν = 1435.1326 ± 0.0030 cm^?1 and a set of upper state constants were obtained for the ν₃ band of CH₂D₂. Although a slight perturbation was noticed in the ν₃ band, all wavenumbers have been fitted with a standard deviation of 3.8 × 10^?3 cm^?1.     

Vibrational spectra and force constants of symmetric tops: ν1, ν5, and 2ν5 of CF335Cl and CF337Cl

The gas phase infrared spectra of CF₃³⁵Cl and CF₃³⁷Cl have been recorded in the ν₁ region and 2ν₅ regions with a resolution of 0.09 cm^?1. Additionally the ν₅ fundamental of CF₃Cl, with natural isotopic abundance, has been reinvestigated with a resolution of approximately 0.36 cm^?1. Molecular constants have been evaluated from the observed spectra by means of polynomials and band contour simulation. The possibility of a Fermi resonance between ν₁ and 2ν₅ is discussed.     

The Infrared Spectrum of CCH2: The Bending States up to v4+v5=4

The vibration-rotation spectra of ¹³C monosubstituted acetylene, ¹²C¹³CH₂, have been recorded in the region between 450 and 3200 cm⁻¹ with an effective resolution ranging from 0.004 to 0.006 cm⁻¹. A total of about 5300 rovibrational transitions have been assigned to 53 bands involving the bending states up to v_t=v₄+v₅=4, allowing the characterization of the ground state and of 30 vibrationally excited states. All the bands involving states up to v_t=3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model larger discrepancies between observed and calculated values have been obtained for transitions involving states with v_t=4. These could be satisfactorily reproduced by only adopting, in addition to the previously determined parameters which were constrained in the analysis, a set of effective constants for each vibrational manifold.     

High-resolution infrared spectrum of carbon suboxide: The ν4 + 2ν70 and ν4 + 3ν71 − ν71 bands

The infrared spectrum of the ν₄ + 2ν₇ progression of C₃O₂ has been recorded with a resolution of about 0.018 cm^?1. Two bands of the progression have been completely analyzed. The band centers obtained in this study establish, when combined with previously published experimental results, than 3ν₇¹ is 97.22 cm^?1 above the ground vibrational state.