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High resolution measurements of room temperature absorption with a controlled tunable diode laser (TDL) spectrometer have been made for R (2) and P (14) lines in the HCl fundamental band perturbed by N 2 , Xe, Ar and He at pressures lower than one atmosphere. Pressure broadening, shift and collisional narrowing parameters have been extracted by least-squares fitting of several collisional profiles to the spectra. Asymmetries are observed for P (14) broadened by Xe at the lowest pressures and attributed to correlations between velocity- and phase-changing collisions.

We report the nitrogen-induced shifting coefficients of 37 water vapour rovibrational transitions in the 1845–2140 cm−1 spectral region. The measurements were made with a Fourier transform spectrometer at Paris University in the 258–330 K temperature range at a spectral resolution of 0.005 cm−1 for lines with low state rotational quantum number up to 14. The measured exponents of the temperature dependence of the width exhibit a large range of values from 0 to 2.5. Theoretical calculations are based on impact theory modified by introducing additional parameters to extend the use of empirical data. The model parameters are determined by fitting the broadening and shifting coefficients to experimental data. The calculated line shift coefficients as well as the temperature exponents for the line shift agree satisfactorily with measured values.

This work is mainly motivated by the atmospheric importance of formaldehyde. The 3.5 μm region is indeed commonly used for the infrared detection of this molecule in the troposphere and the line parameters which are presently available in the atmospheric databases for H 2 CO are of rather poor quality in this spectral range. Using New Fourier transform spectra recorded in LPMA and in GSMA it has been possible to perform an extensive study of the 2ν 4 , ν 4 +ν 6 , 2ν 6 , ν 3 +ν 4 , ν 3 +ν 6 , ν 1 , ν 5 , ν 2 +ν 4, 2ν 3 , ν 2 +ν 6 and ν 2 +ν 3 bands of formaldehyde. Combining these data with previous frequency and intensity measurements for the ν 3 +ν 4, ν 3 +ν 6 , ν 1 , ν 5, ν 2 +ν 4, 2ν 3 and ν 2 +ν 6 bands [L.R. Brown R.H. Toth and A.S. Pine J. Mol. Spectosc. 406–428 and references therein] and an adequate theoretical model, it proved possible to reproduce rather satisfactorily the experimental data and to generate a list of line positions and intensities for the 3.5 μm region. The Hamiltonian model accounts for the various Coriolis-type resonances and anharmonic resonances which perturb the energy levels of the 4 2 , 4 1 6 1 , 6 2 , 3 1 4 1 , 3 1 6 1 , 1 1 , 5 1 , 2 1 4 1 , 3 2 , 2 1 6 1 , and 2 1 3 1 vibrational states. This is also the case for the line intensity calculations, which allow one to reproduce satisfactorily the line-by-line intensity measurements as well as the integrated intensities available in the literature.

We present a complete study on four methane lines for two atmospheric micro-windows (in the ν 2 + ν 4 absorption band) used for the determination of atmospheric methane concentrations with ground-based Fourier transform spectrometers. Thanks to our tunable diode laser (TDL) spectrometer with active wavenumber control and step-by-step recording mode we have improved the accuracy on intensity, broadening, narrowing, and pressure shift parameters. To make our results directly useable in atmospheric models which usually assume a Voigt line shape, we have parameterised an effective-broadening parameter γ Voigt ( P ) for each line and each gas mixture (CH 4 –N 2 and CH 4 –O 2 ). When this parameterisation is used to fit a “true” line profile, the same concentration as with more sophisticated models is retrieved using a consistent set of spectroscopic parameters in both approaches.

In this paper, we present a line profile study of the R (0) line in the ν 4 band of methane diluted in nitrogen and oxygen, from room temperature to 153 K. The measurements were performed over a total pressure range from 14 to 128 mbar. The collisional broadening and narrowing (Dicke effect) coefficients are derived from a fit of the experimental spectra by using the soft and hard collision models, taking into account the Dicke effect. For higher pressures, we have fitted the data with a model taking into account simultaneously the Dicke narrowing and the speed dependence effect. Finally, we have deduced the parameter n of the temperature dependence (inverse power law) of the broadening coefficients for the CH 4 –N 2 and CH 4 –O 2 gas mixtures.

We have constructed a stabilized low temperature infrared absorption cell cooled by an open cycle refrigerator, which can run with liquid nitrogen from 250 to 80 K or with liquid helium from 80 K to a few kelvin. Several CO infrared spectra were recorded at low temperature using a tunable diode laser spectrometer. These spectra were analyzed taking into account the detailed effects of collisions on the line profile when the pressure increases. We also recorded spectra at very low pressure to accurately model the diode laser emission. Spectra of the R(2) line in the fundamental band of 13 CO cooled by collisions with helium buffer gas at 10.5 K and at pressures near 1 Torr have been recorded. The He-pressure broadening parameter (γ0=0.3 cm−1 atm−1) has been derived from the simultaneous analysis of four spectra at different pressures.

Simultaneous ultraviolet (UV) and infrared (IR) measurements of ozone concentration in air in the 1200-300 ppbv range have been performed using the ultraviolet absorption in the Hartley band at 0.2537 microm and the infrared absorption of a doublet at 9.507 microm in the nu(3) vibration-rotation band. Infrared concentration measurements were achieved using the tunable diode laser spectrometer of LPMA in Paris with interferometric control of the emitted wavelength while the UV concentration measurements were performed with the 49PS Megatec ozone generator of the Bureau National de Metrologie (BNM). The simultaneous recording of spectra of a reference cell filled with pure distilled ozone and of a low concentration mixture inside a long absorbing path Herriott cell allows to carry out infrared concentration measurements with an accuracy of the same order as the ultraviolet ones and provides the instrumental parameters of the spectrometer corresponding to each concentration measurement, which reduces systematic errors. Within the respective absolute uncertainties proper to the two techniques, no systematic discrepancy was evidenced between the IR and the UV measurements. The ozone ultraviolet absorption coefficient value determined by Hearn (308.3 +/- 4 cm(-1)atm(-1)) and used by the BNM and the National Institute of Standards and Technology (NIST) is confirmed by the present work.

We present a line profile study at 150, 110 and 80 K for the R(7) line in the fundamental band of 13CO perturbed by Ar in a new stabilized low-temperature cell cooled by liquid nitrogen. The broadening, shifting and narrowing parameters are determined taking into account the absorber speed dependence by simultaneous least-squares fitting of spectra over a 4–300 Torr pressure range recorded using a frequency-stabilized diode laser spectrometer. When the cell is cooled by liquid helium the (1–0) R(2) line of 13CO in collision with helium is observed at a temperature of 6.9 K.

Forty-seven N 2 broadened water vapor line-widths have been measured in the 1845–2140 cm −1 spectral range with a Fourier Transform spectrometer in the 258–330 K temperature range at a spectral resolution of 0.005 cm −1 for the lines with upper state rotational quantum number up to 16. The measured exponents of the temperature dependence of the width exhibit a large range of values from 1.60 to −0.86. Theoretical calculations were made using a semi-empirical technique based on the Anderson theory. The calculated broadening coefficients as well as the temperature exponents for the half-width agree satisfactory with measured values.

We present measurements of Ar-broadening parameters for the R(0) and R(7) lines in the fundamental band of13CO at eight temperatures from 80 to 297 K. The broadening parameters are determined by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The comparison of the broadening parameter values for R(7) derived at room temperature and different pressures from different line profiles shows that an empirical line profile, which takes into account narrowing effects (Dicke narrowing and absorber speed dependence) but neglects any correlation between collisions, is able to describe the observed lines with constant values of the narrowing and broadening parameters over a 10-500 Torr pressure range. Starting from a recent ab initio potential energy surface, theoretical thermally averaged close coupling values of the Ar broadening parameter are calculated for the same temperatures. The comparison between experimental and calculated values shows an overall agreement of 1.5%. © 2003 Elsevier Inc. All rights reserved.

We present a line profile study for two lines in the 2 ν 3 band of CH 4 recorded with a frequency stabilized tunable diode laser spectrometer. The broadening and narrowing (Dicke effect) parameters of the R (0) line perturbed by N 2 , O 2 , and He are derived from a simultaneous fitting of spectra at pressures from 20 to 300 Torr by using the soft and hard collision models. These parameters are determined for the A and F components of the unresolved R (3) manifold perturbed by N 2 , Ar, and He from the line profile analysis of spectra at pressures between 50 and 500 Torr. The line mixing effect between the two F components is also taken into account and the absorber speed dependent effect on broadening is estimated for N 2 and Ar.

For the first time a very weak N–N stretching band (ν5) of hydrazine was unambiguously assigned in the Fourier-transform infrared spectrum. Almost 1500 transitions with a resolution of 0.002 cm −1 for K′ from 0 to 6 and for all symmetry species have been analyzed. Despite some perturbations a global fit has been carried out successfully and the band center was determined at 1077.24056(82) cm −1 , much higher than previously expected.

The method of effective operators has been applied to the global fitting of line intensities of the acetylene molecule in the middle infrared. Simultaneous fittings of recently observed line intensities in the cold and hot bands lying in the 13.6, 7.8, and 5 μm regions have been performed. The eigenfunctions of the effective Hamiltonian developed for the global treatment of the vibration–rotation line positions of acetylene [O.M. Lyulin, V.I. Perevalov, S.A. Tashkun, J.-L. Teffo, in: Leonid N. Sinitsa (Ed.), 13th Symposium and School on High Resolution Molecular Spectroscopy, Proceedings of SPIE, vol. 4063, 2000, pp. 126–133] have been used in the calculations. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental accuracy. The importance of l -type resonance, responsible for some large differences between intensities of the same lines in subbands having opposite parities, is exhibited and discussed.

We have determined the spectroscopic parameters that are necessary to describe accurately the R (0) line profile of the CH 4 2ν 3 band from about 1 Torr to a few hundred Torr of pure CH 4 . The intensities determined at each pressure are in overall agreement to better than 0.7%. The R (3) manifold of the same band has also been investigated. Relative positions and absolute intensities of the three transitions composing the triplet have been determined. The intensity distribution inside the triplet is in fair agreement with recent theoretical predictions.

In order to study absorption line profiles using the stabilized diode laser spectrometer of Laboratoire de Physique Moleculaire et Applications (LPMA), a reliable determination of the emission line shape of different diodes laser is needed. In the near infrared region (1.39 and 1.66 microm) we used Distributed Feed Back diode lasers which operate around room temperature and in the middle infrared (5 and 8 microm) we used lead salt diode lasers cooled in a helium closed cycle cryostat or in a liquid nitrogen dewar. Some results obtained in H2O line profile studies in the 1.39 and 5 microm regions are presented as examples demonstrating how absorption line profile measurements can lead to erroneous values of the spectroscopic parameters when the contribution of the diode laser emission line width is neglected.

Measurements of transmission spectra in the infrared have been made in order to test the quality of the theoretical and numerical approach developed in paper I. Two different laboratory experiments have been built which try to simulate optical paths representative of those involved by plume signature. The first, based on a 50 m long White cell and a grating spectrometer, provides experimental results for optical paths of up to about 1 km . These data, representative of the atmospheric paths involved by the considered signature applications, enable a check of the model used for far line wings. In the second set-up, a Fourier transform spectrometer is used with two adjacent cells, which are at high and low temperature, respectively. This configuration schematizes the hot+cold gases that are involved in plume signature. Comparisons between measured and computed values demonstrate the quality of the model and data used. Only small discrepancies remain which are due to imperfections of spectroscopic databases and the neglect of line-mixing effects.

The R(0) line profile of the 13 CO fundamental band is studied at low concentration in helium from room temperature (296.7 K) to 40 K. A narrowing effect due to molecular confinement (Dicke effect) is observed and analyzed using the Galatry soft collision model. The narrowing parameter is found to be in good agreement with the dynamic friction coefficient deduced from the diffusion coefficient over the entire temperature range.

The effective operator approach is applied to the calculation of the spectra of 16 O 12 C 17 O and 16 O 12 C 18 O in the far infrared. Using the eigenfunctions of the effective Hamiltonians previously derived for each of these species, parameters of the corresponding effective dipole moment operators have been fitted to more than 400 observed line intensities of cold and hot bands covering the ν 2 and ν 1 spectral regions. New line intensities measurements in the ν 2 band region of 16 O 12 C 18 O have been performed. The new observed line intensities have been also included into the corresponding fit. The fittings have been achieved within the experimental errors. A comparison of calculated line parameters with those provided by the HITRAN and GEISA databases is given.

Collision effects on water vapor line profiles perturbed by nitrogen at room temperature have been studied by Fourier transform and tunable diode laser spectroscopy. Narrowing effect due to molecular confinement (Dicke effect) has been observed for P and Q branch lines of the ν 2 band of H 2 O with Fourier transform spectrometer. Narrowing and broadening parameters have been determined using the soft and hard collision models. A more precise study on three R -branch lines with a frequency stabilized diode laser spectrometer allows to perform the comparison between the two collision models at low pressure and to analyze the different narrowing effects when the pressure increases taking into account the molecular confinement and the absorber speed dependent effects.

The Proterozoic Pahtohavare Cu-Au deposit in the northernmost part of Sweden within the Fennoscandian shield consists of a syngenetic stratiform sulphide-magnetite mineralisation (East Ore) which is uneconomic and three stratabound to discordant epigenetic Cu-Au mineralisations (Central, South-East and South Ores) hosted by the Viscaria formation. These epigenetic deposits are hosted by fine-grained albite felsite formed by alteration of graphitic schist while the East Ore is hosted by tuffite. The black graphitic schist have acted as a chemical trap for the mineralising fluids explaining the decomposition of the graphite within the schist proximal to mineralised zones and altering it into albite felsite. The past tectonic events made the Kiruna area having a favorable permeability for epigenetic solutions like saline hydrothermal fluids. This favourable permeability is one of the main important characteristic which explains the formation of Pahtohavare ores. A scapolite-biotite alteration is enveloping the albite-altered mineralised zone and occurs in all stratigraphic units. One albite alteration of the tuffite is related to the intrusion of the footwall mafic sill and the other one is an additional ore-related mineralised albitization which is distinguishable by the lack of spatial relationship with the mafic sill and the occurrence of disseminated Ferro-dolomite. Chlorite has been formed by replacement of biotite and amphibole. A negative correlation between Mg and Cl contents of amphiboles is distinguishable which indicates that Mg-Cl avoidance mechanisms can control the incorporation of halogen in the amphibole structure. Scapolite from scapolite-biotite alteration surrounding the ore-bearing albite felsites and ore veins have a dominantly marialitic composition which indicates that the alteration must have been due to highly saline fluids. The occurrence of dipyre in Pahtohavare can be explained by the fact that the formation of the deposit happened in a Na-Cl rich environment. The main ore minerals are chalcopyrite and pyrite occurring disseminated, as veinlet, or filling breccias, and they are often associated with quartz and carbonate. Pyrrhotite is locally significant. Accessory minerals such as sphalerite, galena, millerite, native gold, tellurobismuthite, altaite, molybdenite, tellurides, and native gold in epigenetic ores occur as inclusions in sulphides and quartz.Alteration zones surrounding the Pahtohavare ores have chemical and mineralogical zonations similar to Rakkurijärvi. The Mg-content of biotites decreases toward the ores of the South, East and South East zone. Addition of potassium and depletion of calcium and manganese are characteristic of the biotite-scapolite alteration zone. The ore-bearing albite carbonate alteration zone shows a depletion of K2O and an addition of Na2O, CaO and MnO. The relation between the depletion of Na and scapolitisation-albitisation is close as it is likely due to Na-Ca exchange reactions. Co-variation diagrams are good geochemical discriminants which can be used as exploration tool. The alteration characteristics of the Pahothavare deposit share similar features with other iron oxide and sulphide deposits such as e.g. Bidjovagge, Norway. The sodic alteration is the most important one because of its association to the mineralisation. There are two generations of ore-forming fluids at Pahtohavare. The main physicochemical parameters that controlled hydrothermal alteration and gold mineralisation are pH, ƒO2 and temperature. The decrease of ƒO2 triggered the replacement of pyrite by pyrrhotite and its occurrence is spatially related to the mineralisation. The magnetite-pyrite and hematite-pyrite assemblages may have buffered the pH increase and ƒO2 decrease of the ore fluids. The chloride complexes of copper and gold are the most important one concerning the transport. The destabilization of gold chloride complexes is the main mechanism of gold deposition. This destabilization is due to an increase of pH from CO2 loss, cooling and dilution of the solution. The high salinity of the fluid can be explained by the metasomatic hydration of biotite and amphibole formation. Salinity is an important factor which determines the precipitation of metals from chloride complexes. Pahtohavare is considered as a copper deposit because of the low concentrations of gold due to the low initial concentrations of gases in the ore fluid and the fluids have not reach the native gold solubility 103 ppb limit for Cl complexes but has crossed the copper 100 ppm limit for Cl complexes. The copper content of the hypersaline brines at Pahtohavare have a range of 100-500 ppm which is comparable to saline magmatic fluids of the Cloncurry district in Australia. Validerat; 20140325 (global_studentproject_submitter)

Using a stabilized diode-laser spectrometer, we have studied the line profiles of water vapor near 7185.59 cm(-1). With low pressures of pure gas (/=1,Torr) in a White-type cell, we have deduced the line intensities using the Voigt profile. This study shows clear differences between experimental and calculated lines described by a Voigt profile when the pressure increases. For water vapor in mixtures with N(2), O(2), Ar, or He, we have determined the collisional broadening coefficients, taking into account the collisional narrowing (Dicke effect). The narrowing parameters have been determined using soft (Galatry) or hard (Rautian and Sobel'man) collision models and compared to the dynamic friction coefficient. Copyright 2001 Academic Press.

The nu(5) fundamental (C-C stretching) of CH(3)CD(3) shows a resolved torsional structure, caused by perturbations due mainly to the linear dependence of the torsional potential barrier on the normal coordinate Q(5). We were able to analyze this structure and to assign vibration-rotation transition wavenumbers for all five torsional components, classified according to the symmetry species of the G(18)((3)) extended molecular group. The torsional splitting pattern is qualitatively similar to that of a nondegenerate vibrational state with an even number of excited torsional quanta v(6). Explorative calculations show that the main perturber system should consist of the torsional components of the vibrational ground state correlating with v(6)=4 in the high barrier limit. The strength of the perturbation on the E(r0) torsional components of nu(5) increases rapidly with r, the E(40) component being the most affected. The observed transition wavenumbers can be reasonably fitted by a simplified model containing independent effective vibration-rotation parameters for the five different torsional components of nu(5), for both CH(3)CD(3) and (13)CH(3)CD(3). The trend of the determined values of the effective vibrational wavenumbers and rotational parameters over the torsional components supports the proposed vibration-torsion interaction mechanism, responsible for the observed torsional splittings. A strong anomaly observed in the rotational intensity distribution of nu(5) is discussed. Copyright 2001 Academic Press.

We determined accurate He-broadening parameters and collisional cross sections for the P(2) line in the fundamental band of CO at room temperature and at intermediate temperatures down to 11.5 K. We also determined a precise value for the temperature dependence of the line-broadening parameter on (T)(-n) with n equal to 0.548+/-0.010. Our results validate the microwave results for the J=1 to J=2 rotational transitions measured over the same range of temperatures which were reported previously by Beaky et al. (1996, J. Chem. Phys. 105, 3994-4004). Copyright 2001 Academic Press.

Collision effects on water vapor at low concentration in mixture with noble gases and nitrogen have been studied by Fourier transform spectroscopy in a pressure range where line narrowing by dynamic confinement (Dicke effect) and collision broadening are observable, i.e. when the Voigt function cannot reproduce the observed profiles. Precise values of the broadening parameter have been obtained for R branch lines of the ν2 band of H2O and narrowing parameter values were derived using the soft and hard collision models. Furthermore, it is shown that, when neglecting the confinement effect, systematic errors on the broadening parameters may be introduced and reach several percents for the narrowest lines corresponding to the highest J values.

Using 0.002 cm −1 resolution Fourier transform absorption spectra of an 17 O enriched ozone sample, an extensive analysis of the ν 3 band together with a partial identification of the ν 1 band of the 16 O 17 O 17 O isotopomer of ozone has been performed for the first time. The experimental rotational levels of the (001) and (100) vibrational states could be satisfactorily reproduced using an Hamiltonian matrix which takes into account the observed rovibrational resonances. Actually, as for other C s -type ozone isotopomers [J.-M. Flaud and R. Bacis, Spectrochimica Acta, A54 (1998) 3–16], the (001) rotational levels are involved in both Coriolis and Fermi type resonances with the levels from the (100) vibrational state. Using an Hamiltonian matrix which takes explicitly into account these resonances precise vibrational energies and rotational and coupling constants were deduced and the following band centers ν 0 ( ν 3 )=1017.5336 cm −1 and ν 0 ( ν 1 )=1080.153 cm −1 were obtained for the ν 3 and ν 1 bands respectively.

Infrared spectra of a carbon dioxide sample enriched with oxygen-17 have been recorded with a resolution of about 0.0025 cm-1 in the region of the laser bands near 10 and 9 µm, using the long path difference Fourier Transform Spectrometer of the LPMA in Paris. The two laser bands of the 16O12C17O and 17O12C18O species have been analyzed for the first time. Line intensities for several isotopic species have been measured in this region and the rotationless transition dipole moments and Herman-Wallis coefficients of the corresponding bands have been reported. In particular intensities, alternation in the spectra of 17O12C17O has been analyzed. Copyright 1999 Academic Press.

The nitrogen pressure shifting coefficients for the 150 water vapor lines in the ν 2 band have been measured with the Fourier transform spectrometer located at the Paris VI University with the spectral resolution of 0.005 cm −1 and at room temperature. The measurements were performed for lines having lower state angular moment up to 16, the measured values are found to range from + 0.015 to −0.0293 cm −1 /atm. The J -dependence of the line shift coefficients was studied using the Anderson-Tsao-Curnutte model and cut-of-free method. Fairly satisfactory agreement between measured and calculated line shift coefficients has been found.

Infrared spectra of a carbon dioxide sample enriched with oxygen-17 have been recorded with a resolution of about 0.0025 cm −1 in the regions of the fundamental bands ν 2 (600–800 cm −1 ) and ν 3 (2200–2400 cm −1 ), using the long path difference Fourier transform spectrometer of the LPMA in Paris. The ν 3 fundamental bands of 17 O 13 C 17 O and 17 O 13 C 18 O have been studied for the first time. For each species a simultaneous reduction of all spectroscopic data has been carried out, yielding new or improved spectroscopic constants. Line intensities of the ν 3 band of 16 O 13 C 17 O have been also reported, and isotopic rules for the rotationless transition dipole moment of carbon dioxide have been used to derive calculated values from isotopic substitution for ν 3 bands which are compared with experimental ones.

The ν 6 band of methyl chloride centered near 1018 cm −1 has been recorded with a precise homemade Fourier transform spectrometer. About 5400 lines of this band have been assigned. The ground state constants for both isotopomers, CH 3 35 Cl and CH 3 37 Cl, were obtained from combination differences of the wavenumbers and the upper state constants were deduced from a least-squares fit procedure which permits reproduction of the observed wavenumbers with a standard deviation of 1.1 × 10 −4 cm −1 , close to the experimental uncertainty.

We present experimental and theoretical results for the Q-branches of the (12201 ← 01101) and (20001 ← 01101) bands of 12C 16O2 lying near 4.7 μm perturbed by He. Measurements were carried out with the LPMA Fourier transform interferometer at room temperature and for atmospheric helium pressures. Computations, within the framework of the impact approximation, take into account line mixing effects. The relaxation matrix is modelled with the Energy Corrected Sudden (ECS) approximation derived from the Infinite Order Sudden (IOS) formalism proposed by Green [J. Chem. Phys. 90, 3603 (1989)] which is valid for all type of vibrational band. Strong deviations from the sum of the Lorentz shape are observed in the experimental spectra. The ECS calculations account for these experiments quite satisfactorily.

The pressure-induced shifting coefficients for He-, Ne-, Ar-, Xe-, N 2 -, and O 2 -broadened lines of CO in the fundamental band have been measured by using a Fourier transform spectrometer. The lineshifts have been determined from the wavenumber differences between the lines of pure CO at low pressure and the pressure-broadened lines of CO in mixture with one of the perturbers above mentioned. Comparisons were made with results of theoretical calculations based on a semiclassical model and different isotropic and anisotropic intermolecular potentials. The general trends of the shifts with rotational quantum number are reproduced by the calculations, but not the finer details and the observed asymmetry behavior of the shifts for P and R branches.

Pressure-shifting parameters in the ν3 band of N2O are reported for five perturbers: N2, O2, He, Ar, and Xe. They were obtained with two spectrometers built in our laboratory: a Fourier transform spectrometer yielding a 0.5 × 10−3 cm−1 atm−1 precision for these parameters, thanks to a precise modelling of its apparatus function, and a T.D.L. spectrometer insuring a 0.2 × 10−3cm−1 atm−1 precision, which permits to check the F.T. results for a few lines. The experimental values are compared with values computed from a semi-classical model.

The wavenumber λ d of a tunable diode laser (TDL) is actively forced to preserve its interference order k d through a Michelson interferometer with a path difference D ( D = k d × λ d ). This path difference and its variation ΔD are controlled by a stabilised He Ne laser. A change ΔD induces λ d to change by an amount Δλ d . This procedure reduces by two orders of magnitude the usual jitter of a TDL wavenumber emission. Several applications of this precise instrument (line shifts, line mixing effect, deconvolution of denses spectra) are given.

The interference pattern obtained from a tunable diode laser beam through a stepping Michelson interferometer allows active control of its emission frequency. Two illustrations are given: (a) the N2O concentration (≈ 100 ppbv) in stratospheric air samples has been measured with a precision of 3%. (b) the R(23) line of the CO fundamental band is analysed from a very low pressure of pure gas to pressures of about 1 atm in a CO-Xe gas mixture. Doppler, Dicke confinement and speed-dependent collision broadening effects act successively when the gas pressure increases. The narrowing parameter obtained by fitting the hard collision model (Rautian Sobel'man profile) to the observed line at pressures ⩽ 40 Torr gives a value of the diffusion coefficient close to the value deduced from the transport properties of gas mixtures.

Line-mixing effects have been studied in two Q branches of the absorption spectra of CO 2 , in mixtures with nitrogen, oxygen, and argon. The corresponding transitions are (20 0 0) I ← 01 1 0 and (12 2 0) I ← 01 1 0, centered near 2130 cm −1 and 2093 cm −1 , respectively. Line-mixing effects have also been examined in two Q -branches of pure N 2 O, corresponding to the 13 1 0 ← 00 0 0 and 13 1 0 ← 01 1 0 transitions, centered near 3046 cm −1 and 2457 cm −1 , respectively. Good agreement is obtained between the experimental results and computations taking line mixing effects into account with a phenomenological model for the relaxation matrix.

The two infrared active C–D stretching bands ν6and ν8of C3D6were recorded on a large Fourier transform spectrometer with a linewidth close to the Doppler–Fizeau limit. The perpendicular band of theE′ vibration ν8near 2209.6 cm−1is found to be highly perturbed by anharmonic resonances with the states ν7+ 3ν14, ν7+ ν9+ ν14, and ν4+ ν10+ ν14, and by aJx,yCoriolis-type interaction with an unidentified[formula]state. In contrast, the structure of the parallel band of the[formula]vibration ν6near 2336.7 cm−1appears to be relatively unperturbed. Spectroscopic constants are reported for the two fundamentals and for some of the perturbers of the ν8state.

A description is reported of the 22 m maximum path difference Fourier transform spectrometer built in the laboratory in order to obtain Doppler limited spectra of heavy molecules in the infrared region. Main limitations in resolution and spectral line parameter measurements are given for this spectrometer at the present time of its evolution.

Line-mixing effects have been observed with a Fourier transform spectrometer in two Q branches of the absorption spectra of CO 2 , corresponding to the (20 0 0) I ← 01 1 0 and (12 2 0) I ← 01 1 0 transitions centered near 2130 and 2093 cm −1 , respectively. The gas pressure was raised to 3 atm and the path lengths have been chosen in order to study the center as well as the wings of these two Q branches. Good agreement is obtained between the experimental results and computations taking line mixing into account with a phenomenological model for the relaxation matrix.

Using new high resolution Fourier transform spectra (R ∼ 0.002 cm−1) recorded in the 1190-1340 cm−1 spectral region, it has been possible to improve noticeably upon a previous analysis (A. Perrin, J.-M. Flaud, C. Camy-Peyret, A. Goldman, F. J. Murcray, and R. D. Blatherwick, J. Mol. Spectrosc.142, 129-147 ( 1990)) of the ν6 band of H2O2. More levels have been observed for the ν6 torsional substates (n, τ) = (0, 1), (1, 1), (2, 1), (0, 3), (1, 3) and the theoretical model has been improved. Indeed, in addition to the (Δτ = ±1, ΔKa = ±2) torsion-rotation resonances within the ν6 = 1 vibrational state, which are usually observed for H2O2, the energy level calculation takes into account the ν2 = 1 ↔ ν6 = 1, ν3 = 1 ↔ ν6 = 1 and ν = 0 ↔ ν6 = 1 vibration-rotation resonances. In this way excellent agreement was obtained for the torsion-rotation levels, especially for τ = 3. For the τ = 1 torsion-rotation levels the agreement is less satisfactory because in this case the scheme of vibration-torsion-rotation resonances is much more complicated. Also, precise line intensities were measured and satisfactorily calculated, and a synthetic spectrum of the ν6 band of H2O2 was generated.

The perpendicular infrared bands of the E ′ vibrations of C 3 D 6 were recorded on a large Fourier transform spectrometer at resolution approaching the Doppler limit, and the "forbidden" pure rotational transitions in the ground vibrational state induced by centrifugal distortion were measured with the aid of a pulsed Fourier transform microwave spectrometer. The unperturbed and well resolved infrared band ν 11 provided extensive data yielding 867 combination differences for a determination of the ground state constants B 0 , D 0 J , and H 0 JKK . These were combined with highly accurate values of C 0 - B 0 , D 0 JK , and H 0 JKK , determined from the microwave measurements of the pure rotational transitions | J , K = ±2〉−| J , K = ∓1〉 to obtain the following values for the ground state constants: B 0 = 0.4613514(4), C 0 = 0.3182425(4), D 0 J = 3.7868(18) × 10 −7 , D 0 JK = −3.7395(7) × 10 −7 , H 0 JKK = −0.561(25) × 10 −12 , and H 0 JKK = 2.24(40) × 10 −12 (all in cm −1 units). These are more accurate by at least two orders of magnitude than previously available values. The ν 10 band was found to have an appearance of a parallel band exhibiting blended p P ( J , K ) and r P ( J , K ) lines as well as r R ( J , K ) and p R ( J , K ) lines with the same J and different K values, which form sharp unresolved spikes for low to intermediate J values even at our high resolution, due to an accidental close match of the values of ( C ζ) and B ′- C ′. Only the high- J R -branch lines are partially resolved. The hot band ν 10 + ν 14 − ν 14 was also analyzed. The ν 9 band exhibits two distinct p P branches resulting from Fermi resonance with 2ν 2 14 . Spectroscopic constants for the upper states ν 11 , ν 10 , ν 9 , and 2ν 2 14 , as well as for ν 10 + ν 14 and ν 14 , obtained from detailed rotational analyses of the bands are reported.

Using high-resolution ( R ∼ 0.002 cm −1 ) Fourier transform spectra of ozone containing about 20% of 17 O 3 isotopic species, it has been possible to observe and assign the {ν 1 , ν 3 } bands of 17 O 3 up to very high rotational quantum numbers. For this analysis, we used the ground state energy levels calculated from the (000) rotational constants obtained for 17 O 3 in a recent microwave study performed by J.-M. Colmont (submitted for publication). Then, from the {(100), (001)} rotational energy levels derived in the present work, a set of molecular parameters (vibrational band centers and rotational and coupling constants) for the {(100), (001)} interacting states of 17 O 3 has been determined using a Hamiltonian matrix which explicitly takes into account the (100) ↔ (001) Coriolis interaction. Finally, using transition moments derived theoretically from those of 16 O 3 , a synthetic spectrum (line positions and intensities) of the ν 1 and ν 3 bands has been generated.

A spectrometer using a monomode tunable diode laser as a source is described. The phase of the emission is controlled by the interference pattern given by a Michelson interferometer. The phase noise is thus drastically reduced and the wavenumber measurement precision is better than 10 −8 . Also, the intensity absorbed by a gas is known to a precision better than 10 −3 . To illustrate the possibilities of the spectrometer, brief examples of inelastic molecular collision effects in gases (pressure broadening, mixing, and shift for V - R lines) will be given. The low noise level and precise wavenumber measurements allowed Pliva to build an effective absorption spectrum with linewidths significantly narrower than Doppler-limited ones using deconvolution methods.

Linestrengths have been measured for three weak bands of 14 N 2 16 O using a Fourier transform spectrometer, with an effective response function width of about 5 × 10 −3 cm −1 . The observed bands are the cold band ν 1 + 3ν 2 , and the hot bands 10 0 1 ← 01 1 0 and 30 0 0 ← 02 0 0. Measurements have been performed with a relative accuracy better than 2%. Analysis of the results yields the squared vibrational transition dipole moments and the parameters describing the vibration-rotation interaction effects. It may be emphasized that, for the 10 0 1 ← 01 1 0 transition, the corresponding quadratic Herman-Wallis parameters are found to be in good agreement with our previous predictions carried out according to Watson′s theory.

Assignments have been carried out for the 2ν3/(ν3+ν6)/2ν6 (triad)←ground state overtone bands and the triad←ν3/ν6 hot‐band system of CHD3. A vibrational extrapolation method, using correspondences between a spherical‐tensor formalism and the more conventional description of symmetric‐rotor spectra, was used to facilitate the assignment and analysis of these bands. The resulting assignments have been confirmed by time‐resolved double‐resonance measurements.

Linestrengths have been measured for 12 bands of N2O using a Fourier transform spectrometer, with an effective response function width of about 5 × 10−3 cm−1. The observed bands for 14N216O are the cold bands ν1 + 2ν2 and 2ν1 and their associated hot bands starting from the 0200 or 1000 levels. Transitions starting from the 0000 level have also been measured for the minor isotopic species 14N218O 15N14N16O, and 14N15N16O. Measurements have been carried out with a relative accuracy better than 2%. Analysis of the results yields the squared vibrational transition dipole moment and the parameters describing the vibration-rotation interaction effects.

Linestrengths have been measured for five bands of 14 N 2 16 O using a Fourier transform spectrometer, with an effective response function width of about 5 × 10 −3 cm −1 . The observed bands are the cold band ν 2 + ν 3 , and the hot bands starting from the 01 1 0 level, associated to the ν 1 + 2ν 2 , 2ν 1 , and ν 2 + ν 3 main bands. Measurements have been carried out with a relative accuracy better than 2%. Analysis of the results yields the squared vibrational transition dipole moment and the parameters describing the vibration-rotation interaction effects. An important contribution of the l -type resonance has been observed for both the 02 0 1 ← 01 1 0 and the 02 2 1 ← 01 1 0 transitions; the corresponding quadratic Herman-Wallis parameters have been calculated and compared to the observed ones.

Within the scope of a general tensorial study of the 1000 and 2000 cm −1 polyads of CHD 3 , we have revisited the ground state of this molecule. Infrared ground state combination differences (GSCD) were calculated from 1746 transitions assigned in the ν 3 /ν 5 /ν 6 triad of CHD 3 . A set of 10 ground state parameters has been fitted to 613 GSCD providing an agreement of 0.00014 cm −1 between observed and calculated transitions. This corresponds to an improvement of about one order of magnitude with respect to the previous study, reflecting the quality of the experimental spectrum as well as a strict selection of the data used to fit the parameters.

Very recently using spectra obtained with a diode-laser technique, a new analysis of the ν 5 and 2ν 9 interacting bands of nitric acid located at 11 μm has been performed [A. G. Maki and J. S. Wells, J. Mol. Spectrosc. 152, 69-79 (1992)]. As compared to this recent analysis, the present work provides: (i) a more extended analysis of the ν 5 and 2ν 9 bands of HNO 3 using a high-resolution Fourier transform spectrum covering the 830-930 cm −1 spectral range, (ii) a different description of the resonances between energy levels of the v 5 = 1 and v 9 = 2 vibrational states of HNO 3 involving both Fermi- and Coriolis-type operators, and (iii) a better description of both the ν 5 and 2ν 9 bands. In this way, it has been possible to generate an accurate linelist of the P , Q , and R stacks of the ν 5 and 2ν 9 bands of nitric acid.