Line intensities in the ν1 + 2ν2, 2ν2 + ν3, 2ν1, ν1 + ν3, 2ν3, and ν1 + ν2 + ν3 − ν2 bands of H216O,between 6300 and 7900 cm−1

Using Fourier transform spectra, the intensities of 428 weak lines belonging to the ν₁ + 2ν₂, 2ν₂ + ν₃, 2ν₁, ν₁ + ν₃, 2ν₃, and ν₁ + ν₂ + ν₃ − ν₂ bands of the H₂¹⁶O molecule have been measured, between 6300 and 7900 cm⁻¹, with an average uncertainty of 7%.     

Line intensities for the ν1, ν3 and ν1+ν3 bands of 34SO2

Using both high resolution (0.0018 cm^?1) and medium resolution (0.112 cm^?1) Fourier transform spectra of an enriched ³⁴S (95.3%) sample of sulfur dioxide, it has been possible to accurately measure a large number of individual line intensities for some of the strongest of the SO₂ bands, i.e. ν₁, ν₃ and ν₁₊ν₃. These intensities were least-squares fitted using a theoretical model which takes into account the vibration–rotation interactions linking the upper energy levels where needed, and, in this way, expansions of the various transition moment operators were determined. The Hamiltonian parameters determined in previous analyses together with these moments were then used to generate synthetic spectra for the bands studied and their corresponding hot bands providing one with an extensive picture of the absorption spectrum of ³⁴SO₂ in the spectral domains, 8.7, 7.4, and 4 μm.     

The 2ν1 + ν3 and 3ν3 bands of 14N16O2

The spectra of the 2ν₁ + ν₃ and 3ν₃ bands of ¹⁴N¹⁶O₂ have been recorded by means of high-resolution Fourier transform spectroscopy and have been extensively analyzed. The (2 0 1) and (0 0 3) rotational levels deduced from the analysis have been reproduced within the experimental uncertainty using a Hamiltonian which takes into account the Coriolis interaction coupling the vibrational states of the diads {(2 2 0), (2 0 1)} and {(0 2 2), (0 0 3)}. Finally, precise sets of vibrational energies, and spin-rotation, rotational, and coupling constants have been derived for these vibrational states.     

Measurements of the line strengths,N2− and O2-broadened half-widths in the ν3, ν1+2ν2 and 2ν1 bands of 14N2 16O at room temperature

The line strengths, N₂? and O₂-broadened half-widths in the ν₃, ν₁+2ν₂ and 2ν₁ bands of ¹⁴N₂ ¹⁶O were determined from spectra obtained by a high-resolution Fourier transform spectrometer at room temperature. The squared vibrational transition dipole moments and the coefficients of the Herman–Wallis factor were also determined for these bands. The squared vibrational transition dipole moments for these bands agreed with the values of HITRAN and high-resolution experiments within 6%. The N₂? and O₂-broadened half-widths were in agreement with the results of recent high-resolution experiments. The air-broadened half-widths were calculated using the smoothed N₂? and O₂-broadened half-widths and compared with the compiled values in the HITRAN database.     

High-resolution investigation of the weak ν1+3ν21-ν21+ν3 band of CO2 around 2 μm

Fundamental spectroscopical parameters of the weak ν₁+3ν₂ ¹-ν₂ ¹+ν₃ band of CO₂ are reported using a high-resolution, direct-absorption spectrometer, based on a distributed feed-back diode laser emitting at 2 μm. Line intensities and self-broadening coefficients have been measured for the first time with high accuracy, for nine lines of the R branch, from R(44) up to R(59). Comparison with available data has been made, and a generally good agreement has been found. Received: 30 August 1999 / Published online: 24 March 2000     

High-resolution measurements of the ν2 and 2ν2-ν2 bands of SO2

Infrared measurements have been made on SO₂ between 450 and 602 cm⁻¹ with a resolution of 0.005 cm⁻¹. The B-type bands due to the bending mode transitions 010-000 and 020-010 have been assigned and analyzed for the ³²S¹⁶O₂ molecule. A total of 3007 transitions were measured and fit for ³²S¹⁶O₂ with a standard deviation of 0.0004 cm⁻¹. Ro-vibrational constants are given that fit the current measurements and the pure rotational transitions reported in the literature.     

Infrared microwave sideband laser spectroscopy of the ν3 and 2ν3 ← ν3 bands of 13CH3F

A large number of transitions in the ν₃ and 2ν₃ ← ν₃ bands of ¹³CH₃F have been recorded at Doppler-limited resolution by means of an infrared laser microwave sideband spectrometer. The sidebands were generated in a CdTe crystal that was simultaneously irradiated by a CO₂ infrared laser and a high-power microwave source operating in the 8- to 18-GHz region. The J and K structures of the bands were well resolved except for the lowest K values. Frequencies of transitions involving J values up to 47 and K values up to 16 are reported. Vibration-rotation parameters for the v₃ = 0, 1, and 2 states were obtained by fitting to the experimental frequencies. These parameters reproduce the experimental values with an rms deviation of 3.8 MHz for the fundamental band and 2.5 MHz for the hot band.     

A high-resolution study of the ν3 and 2ν80 bands of propyne

The ν₃ and 2ν₈⁰ parallel bands of propyne (methyl acetylene) at 2137.88 and 2066.33 cm⁻¹ have been studied at 0.006 cm⁻¹ resolution. Their Fermi resonance and interaction with the ν₈ + 2ν₉, ν₇ + ν₉, and ν₈ + ν₉ + ν₁₀ levels have been investigated. Molecular constants were determined from the assignment of 1150 lines. However, the rms error of 0.0028 cm⁻¹ showed the presence of additional perturbations which cannot be uniquely identified.     

First high-resolution analysis of the ν1, ν3 and ν1 + ν3 bands of sulphur dioxide 33S16O2

• High-resolution spectra of ³³S¹⁶O₂ have been recorded for the first time in the 8 and 4 µm spectral regions.

• The ν₁, ν₃ and ν₁ + ν₃ bands of the ³³S¹⁶O₂ have been analysed up to very high quantum numbers.

• Accurate ro-vibrational upper states constants have been determined.

     

High resolution vibration-rotation spectrum of the D2O molecule in the region near the 2ν1 + ν2 + ν3 absorption band

The high resolution Fourier transform spectrum of the D₂0 (ν = ν₁ + ν₂/2 + ν₃ = 3.5) polyad was analysed within the framework of the Hamiltonian model taking into account resonance interactions between the seven states (310), (211), (112), (013), (230), (131) and (032). Transitions belonging to the 2ν₁ + ν₂ + ν₃, 3ν₁ +ν₂ and 3ν₂ + 2ν₃ bands were assigned in the experimentally recorded spectrum. This provided the possibility of obtaining spectroscopic parameters of the ‘visible’ states (211), (310) and (032) and of estimating the band centres, and the rotational and resonance interaction parameters of the ‘dark’ states (112) and (131).     

Analysis of the High-Resolution Infrared Spectrum of the PHD2 Molecule: ν1 and 2ν1 Bands

The results of investigation into the infrared spectra of the PHD₂ molecule including the ₁ fundamental band centered at 2324.005 cm^–1 (with a resolution of 4.2·10^–3 cm^–1) and the first 2₁ valence overtone centered at 4563.634 cm^–1 (with a resolution of 8.8·10^–3 cm^–1) are given in the present paper. Based on an analysis of the results obtained, 1340 and 1020 lines are referred to the ₁ and 2₁ bands, respectively. This data are used to calculate 316 and 248 vibrational-rotational energies of the (100000) and (200000) excited vibrational states, respectively. Since both bands can be considered as isolated, we take advantage of the Watson Hamiltonian (the reduction A in the I ^r representation) to describe their rotational structure. The calculated spectroscopic parameters of the examined states of the PHD₂ molecule correlate well with each other and with the corresponding parameters of the ground vibrational state.     

High-resolution spectroscopy of difference and combination bands of SF6 to elucidate the ν3 + ν1 − ν1 and ν3 + ν2 − ν2 hot band structures in the ν3 region

The strong infrared absorption in the ν₃ S–F stretching region of sulphur hexafluoride (SF₆) near 948 cm^?1 makes it a powerful greenhouse gas. Although its present concentration in the atmosphere is very low, it is increasing rapidly, due to industrial pollution. The ground state population of this heavy species is only 32% at room temperature and thus many hot bands are present. Consequently, a reliable remote-sensing spectroscopic detection and monitoring of this species require an accurate modelling of these hot bands. We used two experimental set-ups at the SOLEIL French synchrotron facility to record some difference and combination bands of SF₆: (1) a new cryogenic multiple pass cell with 93 m optical path length and regulated at 163 ± 2 K temperature and (2) the Jet-AILES supersonic expansion set-up. With this, we could obtain high-resolution absorption spectra of the ν₃ ? ν₁, ν₃ ? ν₂, ν₁ + ν₃ and ν₂ + ν₃ bands at low temperature. These spectra could be assigned and analysed, thanks to the SPVIEW and XTDS computer programs developed in Dijon. We performed two global fits of effective Hamiltonian parameters. The first one is a global fit of the ground state, ν₂, ν₃, ν₃ ? ν₂, ν₂ + ν₃, 2ν₃ and 2ν₃ ? ν₃ rovibrational parameters, using the present spectra and previous infrared, Raman and two-photon absorption data. This allows a consistent refinement of the effective Hamiltonian parameters for all the implied vibrational levels and a new simulation of the 2ν₃ + ν₂ ? ν₂ hot band. The second global fit involves the present ν₃ ? ν₁ and ν₁ + ν₃ lines, together with previous ν₁ Raman data, in order to obtain refined ν₁ parameters and also ν₁ + ν₃ parameters in a consistent way. This allows to simulate the ν₃ + ν₁ ? ν₁ hot band.     

Analysis of the stimulated Raman spectrum of the ν16ν2 + ν18 Fermi dyad of benzene

Ionization-detected stimulated Raman spectroscopy was used to obtain high-resolution recordings of the two perpendicular bands of the benzene molecule centered at 1591.327 and 1609.518 cm⁻¹. The effective resolution was further enhanced by deconvolving the spectrum to a linewidth 0.003 to 0.004 cm⁻¹. Fine-tuning of the ionizing radiation made it possible to record the transitions belonging to each band separately, thus greatly simplifying the spectrum in the region of overlap. The strong ^sS and ^oO branches were, for the most part, completely resolved as were many lines in the weaker ^oP and ^sR branches and even in the central ^oQ and ^sQ branches. The observed bands belong to the E_2g fundamental ν₁₆ in nearly exact Fermi resonance with the combination ν₂ + ν₁₈. A detailed rovibrational analysis of the spectrum is reported. A perturbation detected in the ^sS_k branches of the lower-frequency band for K = 19 to 23 was identified as a quintic anharmonic resonance with the third overtone, 4ν₂₀, of the lowest lying fundamental ν₂₀, which is infrared- and Raman-inactive (species E_2u). Deperturbed spectroscopic constants for the interacting states are reported which reproduce the observed line positions with a standard deviation of 0.0013 cm⁻¹. The unperturbed origins of the ν₁₆ and ν₂ + ν₁₈ states are only 1.106 cm⁻¹ apart. The fundamental ν₁₆ was identified with the higher-frequency state with origin at 1600.976 cm⁻¹.     

On exact allowance for masses,anomalous magnetic moments,and electric dipole moments of the neutrinos in the ν1 → ν1ν2¯ν2 reaction in an external field

The probability of the process _{1 12}¯₂ in the field of a plane wave is calculated in the general case with allowance for masses, anomalous magnetic moments, and electric dipole moments of the neutrinos. In special cases, earlier results are confirmed. The symmetry of the expression for the integrated probability with respect to the anomalous magnetic moment and the electric dipole moment of the neutrinos is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 101–105, January, 1992.     

Study of the ν3 and 2ν3 ← ν3 bands of 12CH3F by infrared laser sideband and submillimeter-wave spectroscopy

An infrared laser sideband spectrometer operating in the CO₂ laser region with 8- to 18-GHz sidebands has been used to record 266 transitions in the ν₃ band and 84 transitions in the 2ν₃ ← ν₃ band of ¹²CH₃F. The accuracy of the measured frequencies is estimated to be 1–3 MHz. A millimeter/submillimeter-wave spectrometer has been used to record the spectra of 48 pure rotational transitions in the ground vibrational state and 55 transitions in the v₃ = 1 vibrational state with an accuracy of 20–90 kHz. The new measurements have been combined with previous radio frequency and infrared laser results to derive sets of constants for the ground, v₃ = 1, and v₃ = 2 states for this molecule. Tables of the vibrational dependence of the parameters and of the near coincidences of the ν₃ and 2ν₃ ← ν₃ band transitions with CO₂ laser frequencies are given.     

FTIR spectra and rovibrational analysis of parallel bands involving the ν1, ν2, and ν3 levels of natural and monoisotopic FClO3

Fourier Transform infrared spectra of gaseous natural FClO₃ and monoisotopic F³⁵ClO₃ have been recorded at 293 and 225 K with a resolution of 0.04 cm⁻¹. Rotational J structure and, in part, K structure were resolved for the parallel fundamentals, combination bands, and overtones ν₁, ν₂, ν₃, ν₁ + ν₂, ν₁ + ν₃, ν₂ + ν₃, 2ν₁, 2ν₂, and 2ν₃. Band origins ν₀, anharmonicity constants χ_ij, and vibration-rotation interaction constants α_i^A and α_i^B have been determined. For F³⁵ClO₃, ν₀ values are ν₁ = 1063.238(6), ν₂ = 716.814(6), and ν₃ = 549.877(3) cm⁻¹. No perturbation was found at the present level of accuracy.