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The emission spectrum of the C 4 Δ –X 4 Φ Δv=0 transitions of 48Ti35Cl, with v=0,1,2,3, around 3 μm has been recorded with a high resolution Fourier transform spectrometer. Eight new subbands between Δ Ω=−1 spin components of the 1–1, 2–2, and 3–3 transitions are observed. Effective parameters have been derived from the rovibrational analysis, as well as molecular constants from the diagonalization of the Hamiltonian matrix, leading to the equilibrium structure of the 4Δ state. Perturbations affecting the C 4 Δ 1/2 v=0, 1, 2 levels have been accounted for. They arise both from Λ-doubling and avoided crossing phenomena induced by the never observed B 4 Π and A 4 Σ − states.

Time-resolved Fourier transform spectroscopy, with temporal and spectral resolutions respectively at best 1.6 μs and 0.014 cm−1 (Doppler-limited), is applied as a new diagnostic tool to the characterization of nitrogen plasma. A spectral range extending from 0.93 to 1.85 μm is recorded at once. The rotational lines of the B 3Πg→A 3Σu+, Δv = 0,−1,−2,−3 vibronic sequences are fully resolved. Thermodynamical plasma parameters are obtained from line intensity and width analysis. The relaxation of the B 3Πg state of N2 in a pulsed electrical discharge is observed under various pressures and pulse repetition rates. Evolutions of the low-lying vibrational levels B 3Πg,v = 0,1,2 during the early afterglow (post-discharge time period ≤150 μs) are analysed. A simplified kinetic model based on the strong couplings between B 3Πg and A 3Σu+ states and between B 3Πg and W 3Δu states is adopted. It is found appropriate for the interpretation of the spectra within a restricted range (pressure 16–53 Pa (0.12–0.40 Torr), repetition rate 50–200 Hz) of the experimental conditions. Collisional rate constants coupling the B v = 0 level to the levels A v = 7 and W v = 0 are estimated to be kBW = 9×10−12 cm3 s−1 and kBA = 3×10−12 cm3 s−1, in accordance with existing results.

Several hot bands of acetylene in the ∼ 3300 cm −1 region have been investigated in the high-resolution FTIR spectrum recorded at an apodized resolution of 0.0054 cm −1 . Molecular parameters for various stretch-bend levels of 12 C 2 H 2 and 13 C 12 CH 2 from "global fits" of the data are reported.

The high-resolution FTIR spectrum of acetylene in the ∼ 3800 cm −1 region has been analyzed for various hot bands originating from the low-lying ν 4 and ν 5 bending modes. The data have been fitted to a second-order transformed Hamiltonian which includes appropriate off-diagonal terms to account for vibrational and rotational I -type resonances. Parameters for various stretch-bend combination levels, which fit the data with residuals (∼ 2.5 × 10 −4 cm −1 ) approaching the experimental accuracy, are reported.

Using Fourier-transform spectra, absolute line position measurements were performed in the 1 ← 0 allowed subbands of 14 N 16 O for transitions characterized by high J values ( J ≤ 41.5). A global analysis of these new data along with previously published infrared, far-infrared, and microwave data involving the ν = 0, 1, and 2 vibrational states was carried out and yielded improved rovibrational, Λ-doubling, and hyperfine coupling spectroscopic constants. Absolute intensities have also been obtained and the vibrational dipole moment of the 1 ← O subbands, as well as the Herman-Wallis coefficients, were determined through an analysis of these new intensities and of those reported by M. N. Spencer, C. Chakerian, Jr., L. P. Giver, and L. R. Brown ( J. Mol. Spectrosc. 165, 506-524, 1994). These constants and the ones reported for the 2 ← 1 allowed subbands and the 1 ← 0 forbidden subbands were used to compute a complete synthetic spectrum in which line positions were calculated, using the spectroscopic constants obtained in this work and accounting for the hyperfine structure.

Using Fourier transform spectra, absolute line positions and intensities have been measured in the 2 Π 1/2 - 2 Π 3/2 and 2 Π 3/2 - 2 Π 1/2 forbidden subbands of the vibrational 1 ← 0 fundamental band of nitric oxide. To retrieve accurate results from the spectra, the hyperfine structure was carefully taken into account. From the measured line intensities, the vibrational transition dipole moment, as well as the Herman-Wallis coefficients, has been determined for the studied subbands.

After the most prominent bands of propyne (CH3 C C H) in the region of 9-11, 16, and 30 μm have been analyzed, we have undertaken the study of weaker bands in the same regions. The main purpose of this study is to reach all levels in the 900-1100 cm−1 energy range, in order to make possible a global treatment of all these interacting levels. High-resolution Fourier transform spectra have been used in all three regions and also tunable diode laser spectra in the 16-μm region. The major findings concern the (ν9 + ν10)0 PAPE band at 10μm, the (ν9 + ν10)0 - ν10 and (ν9 + ν10)2 - ν10 hot bands at 16 μm, and the (3ν10)3 - (2ν10)2 and (3ν10)1 - (2ν10)0 "superhot hands" at 30 μm. Several local resonances in these bands have also been detected.

Seventy-six individual line intensities of the {ν 5 , 2ν 9 } and {ν 3 , ν 4 } bands of HNO 3 have been measured using high-resolution Fourier transform spectra recorded in the 450-1640 cm −1 spectral range. These intensities were then accurately reproduced using a model which takes explicitly into account both Fermi- and Coriolis-type resonances affecting the { v 5 = 1, v 9 = 2} and { v 3 = 1, v 4 = 1} interacting upper levels of HNO 3 . Finally, synthetic spectra (line positions and intensities) of the {ν 5 , 2ν 9 } (11 μm) and {ν 3 , ν 4 } (7.6 μm) bands of HNO 3 have been generated.

Several bands of 13C12CH2 appearing in the region 2600-3350 cm−1 have been analyzed in the high resolution FTIR spectrum of acetylene. Molecular parameters for the various levels, as well as the deperturbed parameters for the ν3 − (ν2 + ν4 + ν5)0+ Fermi diad, are reported.

After the most prominent bands of propyne (CH3 C C H) in the region of 9-11, 16, and 30 μm have been analyzed, we have undertaken the study of weaker bands in the same regions. The main purpose of this study is to reach all levels in the 900-1100 cm−1 energy range, in order to make possible a global treatment of all these interacting levels. High-resolution Fourier transform spectra have been used in all three regions and also tunable diode laser spectra in the 16-μm region. The major findings concern the (ν9 + ν10)0 PAPE band at 10μm, the (ν9 + ν10)0 - ν10 and (ν9 + ν10)2 - ν10 hot bands at 16 μm, and the (3ν10)3 - (2ν10)2 and (3ν10)1 - (2ν10)0 "superhot hands" at 30 μm. Several local resonances in these bands have also been detected.

A SISAM spectrometer was adjusted. It was fitted with an apparatus for measuring absolute wavelengths. This used the fringes of a Fabry-Perot with emission lines. The results indicate that the width of the apparatus function is less than 0.025 cm(-1) and that the relative accuracy of the wavelength measurements is 0.003 cm(-1).

Recent work aimed at determining the absolute rovibrational transition intensities for the ground electronic state of the hydroxyl radical is reviewed. Two new sets of Fourier transform emission spectra of OH are described which were recorded at the University of Paris and at the Kitt Peak National Solar Observatory.

Here we present the first line‐by‐line measurements of interference parameters Y0k describing line‐mixing effects in the weak overlapping regime for He‐broadened CO lines in the 0–1 and 0–2 bands at 296 K. A detailed analysis of the line shape at intermediate perturber pressures (up to about 10 atm) has been performed, starting from previous theoretical calculations, which has demonstrated the possibility of an individual measurement of Yk parameters. The method is based on the existence of a component of the line shift, quadratic with the perturber pressure (density) and proportional to Y0k. Comparison of our measurements with results predicted from coupled‐states calculations shows good overall agreement. Linear pressure shifts have also been simultaneously measured. The uncertainty on the data is important since linear shifts are very small; however, some features can be considered as significant although we have no clear understanding of them. Possible explanations are discussed.

About 4500 unblended CO lines have been selected and their wavenumbers accurately measured on high resolution solar spectra obtained from space with the ATMOS Fourier transform spectrometer. Half of these lines are of high rotational excitation energy and have never been observed before in the laboratory. Line positions of the fundamental bands of 12 C 16 O have been measured up to J = 133, those of 13 C 16 O and of 12 C 18 O up to J = 103 and 91, respectively. The first overtone bands of 12 C 16 O have been measured up to J = 110. These new solar CO wavenumbers, with an additional selected set of about 14 000 accurate laboratory measurements, have been simultaneously fitted to the Dunham expression utilizing 10 recently published relations between isotopically invariant parameters U ij . The present set of coefficients reproduces all accurate laboratory positions and our solar measurements of high rotational excitation with a standard deviation of about 10 −5 cm −1 (300kHz). This new set is particularly recommended for all high resolution studies of infrared laboratory and stellar spectra showing CO lines of high J -values.

The high-resolution Fourier transform spectrum of acetylene in the 2.4 μm region has been obtained at an apodized resolution of 0.0054 cm −1 . In the analysis of the ( ν 1 + ν 4 + ν 5 ) 2.0 ← ν 4 1 and ( ν 1 + 2 ν 5 ) 2.0 ← ν 5 1 hot bands occurring in this region, the vibrational and rotational l -type resonances have been explicitly taken into consideration. The spectral data have been fitted with residuals approaching the experimental accuracy and molecular parameters have been obtained for the bands investigated. The present studies have also shown that the assignments of the ( ν 1 + ν 4 + ν 5 )(Σ u − ) ← ν 4 (Π g ) and ( ν 1 + ν 4 + ν 5 )(Δ u ) ← ν 4 (Π g ) subbands reported by previous workers must be interchanged.

Reported here are the first intensity measurements of rovibrational transitions for Δv = 1 vibrational bands of the 2Π ground electronic state of SH. The observed relative intensities are strongly perturbed but are consistent with ab initio calculations of the electric dipole moment function, made by J. Senekowitsch, H.-J. Werner, P. Rosmus, and E.-A. Reinsch [J. Chem. Phys. 83, 4661–4667 (1985)] which, in relation to other diatomic hydrides, predict a very large value for the ratio of the permanent electric moment to its first derivative and, therefore, a large Herman-Wallis intensity perturbation. Also consistent with the ab initio calculations is our observation of analogous transitions of SH−, observed on the same spectrum, which display a “normal” intensity distribution.

International audience; Velocity-modulation Fourier transform emission spectra from a N_2O/He discharge plasma recorded between 1 and 5.5 µm are described. Surprisingly, they show Doppler-shifted lines for the E ^2 \Sigma ^+ - D ^2 \Sigma ^+ , C ^2 \Pi - A ^2 \Sigma ^+ , and D ^2 \Sigma ^+ - A ^2 \Sigma ^+ Rydberg-Rydberg rovibronic transitions of the nitric oxide neutral molecule. These polarity-dependent Doppler-shifts are those of positively charged particles. Vibration-rotation lines of NO and transitions from other neutral molecules like N_2 are also present in the spectra with comparable intensities and remain unshifted. Experimental investigations and possible explanations are discussed.

A TiCl4/He plasma is observed by high resolution double-modulation FTS using concentration-modulation as a selective detection method. Analysis of the C4Δ-X4Φ Δv=0 transitions of 48Ti35Cl reveals perturbations affecting the C 4Δ1/2 sub-state.

High sensitivity spectra are obtained around 9500 cm-1 from a semi-conductor Vertical-Cavity-Surface-Emitting Laser (VCSEL) intracavity absorption experiment. Line intensity measurements on the ν3 band of C2H2 and unstable molecules transitions detection are discussed.

The emission spectrum of the fundamental vibration–rotation ν1 band (NH stretch) of iminosilicon HNSi has been observed near 2.7 μm by high resolution Fourier transform spectroscopy from a mixture of N2+SiH4 excited in a radio frequency discharge. This is the first spectroscopic observation of this molecule in the gas phase. Molecular constants σ, B, D, H are reported. Calculated microwave transitions which should be helpful for the investigation and the possible identification of HNSi in astrophysical sources are also given.

The extension of high-resolution observation of the electronic emission spectrum of (14)N(2) toward the infrared domain is presented. To date, rotational analysis of the widely investigated spectrum of the N(2) molecule was done in a spectral domain ranging from 2500 cm(-1) to the UV. We have recorded for the first time the infrared part of the (14)N(2) spectrum from 1250 to 2250 cm(-1), using the Fourier transform spectrometer of Laboratoire de Photophysique Moléculaire (LPPM) at an unapodized resolution of 0.0043 cm(-1). A complete rotational analysis is performed for the (1 --0), (2 --1), (0-- 1), (1-- 2) bands of the B(3)Pi(g)-W(3)Delta(u) system, not included in any previous analysis. Spectroscopic parameters for the v = 0, v = 1, v = 2 levels of the B(3)Pi(g) and the W(3)Delta(u) states, consistent with those previously reported but with improved accuracy, are obtained from the experimental wavenumbers by a nonlinear least-squares procedure. Copyright 1999 Academic Press.

The infrared spectrum of CD 3 Cl has been investigated using a high resolution spectrometer working near 700 cm −1 . This contribution deals with the determination of spectroscopic constants related to the fundamental ν 3 band of the isotopic species CD 3 35 Cl and CD 3 37 Cl and the first hot band, 2 ν 3 - ν 3 , of CD 3 35 Cl.

Infrared emission of a gas mixture of N2 and SiH4 activated by radio frequency discharge has been analyzed using high resolution Fourier transform information. In addition to the several electronic bands of N2, signatures of three transient species--namely, NH, SiN and SiNH--have already been identified. For iminosilicon SiNH this is the first gas phase spectroscopic observation. Molecular parameters have been derived with a high accuracy. For nitride silicon, radical new A2$PI - X2(Sigma) bands have been observed. These data have been combined with other available information in order to improve molecular structure.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Emission spectra of CO2, vibrationally excited by a dc electric discharge, were recorded under Doppler-limited resolution, using a high-information Fourier transform interferometer, in the spectral range of 4–5 μm. Results concerning 49 vibrational transitions with Δv3 = 1 of 12C16O2 are reported. About 2000 wavenumbers, achieving at least a 10-fold improvement in accuracy over previous measurements for all the “hot” transitions, are given with an absolute uncertainty of the order of 10−4 cm−1 for the best of them. The band centers and the spectroscopic constants for all the vibrational levels involved are reported. They reproduce the experimental wavenumbers with a rms of the order of 2 × 10−5 cm−1 for the best vibrational transitions and 3 × 10−4 cm−1 for most of the others. From weighted simultaneous fits of all the experimental wavenumbers, sets of molecular parameters were computed. Fourty-four parameters allow us to reproduce the 2000 experimental wavenumbers with a rms lower than 9 × 10−5 cm−1.

Experimental intensity information is combined with numerically obtained vibrational wave functions in a nonlinear least squares fitting procedure to obtain the ground electronic state electric-dipole-moment function of carbon monoxide valid in the range of nuclear oscillation (0.87 to 1.01 A) of about the V = 38th vibrational level. Mechanical anharmonicity intensity factors, H, are computed from this function for delta V + = 1, 2, 3, with or = to 38.

High-resolution measurements have been performed on 33 emission bands of the carbon dioxide molecule from 4.2 to 4.7 μm. Accurate values of the vibrational and rotational constants of 39 vibration levels were obtained. Molecular constants were calculated from observed wavenumbers.

The halfwidths of CO vibration–rotation lines, pressure-broadened by N2 have been measured in the fundamental band at −83, −148, and −180 °C, using a variable temperature absorption cell and a high resolution spectrometer. The temperature dependence of linewidths has been calculated from the Anderson–Tsao–Curnutte theory and compared to the experimental determinations.

High-resolution emission Fourier spectra have been recorded from a CON 2 HeO 2 mixture excited by dc discharge and cooled by liquid nitrogen. Intensities of all the observed rovibrational lines belonging to sequences Δν = 1, 2 and 3 of 12 C 16 O and 13 C 16 O, and Δν = 1 of 12 C 16 O, have been measured. The data treatment is described. Accurate determination of the rotational distribution and of the vibrational populations of the three isotopic species is performed. The Δν = 2 and 3 vibrational radiative transition probabilities, versus the Δν = 1 ones, are also given, up to ν = 40.

An extensive work on vibration-rotation spectra in the fundamental 1Σ+ electronic state of CO is reported. More than 30 000 Doppler-limited measurements corresponding to about 8500 transitions of 255 bands of 12C16O, 12C18O, 13C16O, and 13C18O, most of them observed for the first time, have been obtained with a high information Fourier transform interferometer on the sequences Δv = 1, 2, and 3. The highest v and J values are 41 and 93, respectively. Experimental vibrational levels are then well observed up to three fourths of the dissociation energy limit. These accurate infrared wavenumbers, with an additional selected set of all previous measurements, have been simultaneously fitted to the Dunham expression in a weighted nonlinear least-squares calculation covering seven different isotopic species. It significantly improves both the number of parameters (U and Δ) obtained by the best previous work (35 instead of 23) and their corresponding standard deviations. The rms of the fit is equal to 13 × 10−6 cm−1 (390 KHz). Calculated wavenumbers from the 35 reduced Dunham and mass-scaling coefficients can then be used as secondary standards, even for transitions involving high v and J values of the various isotopic species. These new parameters should be a convenient and useful tool for several purposes, such as assignment of infrared laser lines and identification of microwave and infrared transitions in astronomical spectra. The Dunham coefficients Y are also reported for 12C16O, 12C17O, 12C18O, 13C16O, 13C17O, 13C18O, and 14C16O. These experimentally determined accurate Y should also be useful for further examination of the potential energy and dipole moment formulations.

Analytical theories of vibrational relaxation of highly excited diatomic molecules are extended, taking into account the two-quantum V-V transfer and radiative processes. The theoretical vibrational distribution functions obtained in this way are compared with those derived from numerical computations and with experimental distributions observed for a natural-abundance 12 C 16 O, 13 C 16 O, 12 C 18 O mixture in a CO laser type cell. In particular, the isotopic enrichments observed in high vibrational levels are compared to the theoretical ones.

A SISAM spectrometer was used for studying the spontaneous emission of a gaseous mixture N 2 ON 2 excited by dc discharge in the 4.7 μm range. Populations of the rotation-vibration levels have been obtained from measurements of line intensities.

High resolution measurements have been performed on 19 emission and absorption bands of the nitrous oxide molecule at 4.7 μm and 2.9 μm. Accurate values of the vibrational and rotational constants of 23 vibration levels were obtained.

A new method for the selective detection of paramagnetic molecules in high resolution Fourier spectroscopy is described. Essentially, it is founded on the circular polarization property of the Zeeman transitions in a longitudinal magnetic field. It is applied to the selective detection of the NO radical created in a N20 electrical discharge.

Emission spectra of the hydroxyl radical have been recorded between 450 and 4200/cm at 0.0027/cm unapodized resolution from an air+oxygen+water vapor plasma, using a surface microwave discharge. The characteristics of the source are described. The emission spectra were recorded with the F.T. spectrometer using a GeCu detector and KCl beams plitter. High J values were observed both for the pure rotational transition in v=0 and v=1 vibrational levels, and for the rovibrational transition in the 0-1 and 1-2 bands. The set of line intensity data will be used to compute the electric dipole moment function of OH.