Collision cross sections, pressure-broadening coefficients and second virial coefficients for the acetylene-argon complex: experiments and calculations on a new potential energy surface.

Integral cross sections and pressure-broadening coefficients have been measured by molecular beam scattering and by high-resolution infrared spectroscopy, respectively, for the acetylene-argon system. A new potential energy surface (PES) is proposed to describe structure and dynamical properties of this prototypical weakly bound complex. The PES has been parametrized exploiting a novel atom-bond pairwise additive scheme and has been fitted to the experimental data.

Line frequency shift measurements by diode-laser spectroscopy for CH(3)D-Xe.

The pressure-induced Xe shifting and broadening coefficients for five lines of 12CH(3)D in the nu(3) band near 7.5 microm have been measured using a tunable diode-laser spectrometer. The frequency shift was determined from the simultaneous record of the Xe-broadened line and the same line of pure CH(3)D at low pressure.

Absolute line intensity measurements of hot bands for carbonyl sulfide at 12 microm.

Using diode-laser spectroscopy, the intensities of 58 lines of the v(1) + v(1/2) - v(1/2) band and 36 lines of the 2v(1) - v(1) band of OCS have been measured. The corresponding band strengths S(0)(v) and the vibrational transition dipoles micro(v) have been derived through least squares fitting of these individual intensities. The band strengths values have been determined with a precision better than 2.

Cyanogen chloride: self-broadening and intensities in the region of 13 microm.

This work presents a synthesis of our results concerning line intensities and self-broadening coefficients for ClCN in the diad (nu1, 2nu 2 0). Absolute band strengths have been determined. The influence of the perturbation in these band strengths due to a Fermi resonance between the 10(0)0 and 02(0)0 levels has been analyzed.

Absolute line intensities determination in the nu7 band of C2H4.

Absolute intensities have been measured for 26 lines of C2H4 in the nu7 fundamental transition, using a tunable diode-laser spectrometer. These lines with 3< or = J"< or = 21, 2< or = Ka< or = 4, 2< or = Kc< or = 20 are located in the spectral range 920-980 cm(-1). The intensities have been measured by using two methods: the equivalent width method (EWM) and the line profile fit method (FPM).

Pressure broadening study of carbon disulfide for atmospheric detection.

Preliminary results for collisional broadening are reported for two lines P(8) and R(32) of the nu3-nu1 band of CS2 in mixture with O2 and air. These values and previous results for CS2-N2 enable us to compare the broadening coefficients directly obtained for CS2-air with those derived from CS2-N2 and CS2-O2.

Diode-Laser Measurements of Absolute Line Intensities in the nu(1) Band of Cyanogen Chloride.

With a tunable diode-laser spectrometer, absolute line intensity measurements have been made in the spectrum of cyanogen chloride in the vicinity of 710 cm(-1). The intensity of the fundamental nu(1) band has been found to be 6.088 cm(-2) atm(-1) for the (35)ClCN isotopomer and 7.

N(2)-Broadening for Methyl Chloride at Low Temperature by Diode-Laser Spectroscopy.

Using a tunable diode-laser spectrometer, we have measured N(2)-broadening coefficients of 87 individual rovibrational lines in the P and R branches of the nu(3) band of methyl chloride (CH(3)(35)Cl) at 203.2 K. These lines with J values ranging from 2 to 22 and K from 0 to 6 are located in the range 711-751 cm(-1).

Absolute Line Intensities and Self-Broadening Coefficients in the nu(1) Band of (35)Cl(12)C(14)N.

The self-broadening coefficients and the intensities of 29 lines in the nu(1) band of cyanogen chloride ((35)Cl(12)C(14)N) have been measured at high resolution in the range 699-736 cm(-1), using a tunable diode-laser spectrometer. The collisional widths and most of the intensities are obtained by fitting Voigt and Rautian profiles to the measured shapes of the lines. From the analysis of the line intensities we determine the absolute strength as well as the Herman-Wallis factors for the nu(1) band.

Absolute Line Intensities in the 2nu(0)(2) Band of Cyanogen Chloride at 12.8 µm.

Absolute line intensities were measured at high resolution with a tunable diode laser. This work concerns the 2nu(0)(2) band of cyanogen chloride ClCN in the region 780 cm(-1). Thirty-two absorption lines were recorded for the isotopomer (35)ClCN and 26 lines for (37)ClCN.

Diode-Laser Measurements of N(2)-Broadening Coefficients in the nu(7) Band of C(2)H(4).

N(2)-broadening coefficients have been measured for 35 lines of C(2)H(4) in the nu(7) fundamental transition, using a tunable diode-laser spectrometer. These lines with 3 View Article and Find Full Text PDF

N(2)-Broadening Coefficients in the nu(1) Band of (35)Cl(12)C(14)N.

N(2)-broadening coefficients have been measured for 30 lines of cyanogen chloride ((35)Cl(12)C(14)N) at room temperature in the P and R branches of the nu(1) band, using a tunable diode-laser spectrometer. These lines, with J values ranging from 0 to 55, are located in the spectral range 694-736 cm(-1). The collisional widths are obtained by fitting the spectral lines with a Voigt and a Rautian profile.

Line-Mixing Effects in He- and N(2)-Broadened Sigma <-- Pi Infrared Q Branches of C(2)H(2).

Two Q branches of C(2)H(2) near 716.3 and 719.9 cm(-1) belonging to the (nu(4) + nu(5))(0) - nu(1f)(4) and 2nu(0)(5)-nu(1f)(5) bands, of Sigma <-- Pi symmetry, have been studied for He and N(2) perturbers at pressures ranging from 0.

N(2) Broadening of Carbon Disulfide (12)C(32)S(2) in the nu(3) and nu(3)-nu(1) Bands.

N(2) broadening coefficients have been measured for 33 lines in the nu(3) fundamental band and 21 lines in the nu(3)-nu(1) band of C(32)S(2), using a tunable diode-laser spectrometer. These lines with J values ranging from 0 to 78 in the nu(3) band and from 4 to 70 in the nu(3)-nu(1) band are located in the spectral ranges 1514-1548 and 853-887 cm(-1), respectively. The collisional widths are obtained by fitting the spectral lines with a Voigt and a Rautian profile.

High-Resolution Spectra of Carbon Disulfide (12)C(32)S(2) in the Region of 2 µm.

By Fourier transform, spectra were recorded for carbon disulfide (12)C(32)S(2) in the region of weak absorption near 5200 cm(-1). The data were fitted and new molecular constants were determined. We also observed a band of the isotopomer (12)C(32)S(34)S.

Inhomogeneous Lineshape Profiles of C(2)H(2) Perturbed by Xe.

Several infrared transitions of the nu(5) band of C(2)H(2) perturbed by Xe near 700 cm(-1) have been recorded using a tunable diode-laser spectrometer, equipped with a thermostatically regulated cell. The pressure and temperature regimes covered during the experiments are respectively ranging between 20 and 200 mbar and 170 and 350 K. The experimental profiles are accurately studied with a recently proposed lineshape model accounting for the collisional confinement narrowing of the Doppler spectral contribution, the inhomogeneous collisional broadening and shifting, and the exchange between the various speed classes of the Maxwell-Boltzmann distribution.

Oxygen Broadening of Acetylene Lines in the nu5 Band at Low Temperature.

O2-broadening coefficients have been measured for 29 lines of C2H2 at 173.2 K in the P and R branches of the nu5 band near 14 µm, using a tunable diode-laser spectrometer. The collisional widths obtained by Rautian profiles closely fitting the measured spectral shape of the lines are slightly larger than those derived from Voigt profiles.

Diode-Laser Spectra of 13C32S2: The nu3 Band.

By diode-laser spectroscopy, spectra have been recorded for isotopically enriched carbon disulfide 13C32S2 in the region of the nu3 band near 1500 cm-1. The data were fitted and new molecular constants were determined. We also observed bands of isotopomers 13C32S33S and 13C32S34S.

Collisional-Broadening Coefficients in the nu6 Band of 12CH3F Perturbed by Ar.

Ar-broadening coefficients are measured for 29 lines of CH3F in the RQ0 and RQ6 branches of the nu6 band, using a tunable diode-laser spectrometer. The collisional widths obtained by fitting Rautian profiles to the measured shapes of the lines are significantly larger, especially for the overlapping lines at low-J values, than those obtained from Voigt profiles. The broadening coefficients for the lines belonging to the same low-J transitions (J = 7-10) appear to be greater in the RQ0 branch than in the RQ6 branch.

Analysis of O2-Broadening of 12CH3F Lines in the 6.8-µm Spectral Region.

Using a tunable diode-laser spectrometer, we have measured the O2-broadening coefficients for 45 lines of methyl fluoride in the QP and QR branches of the nu2 parallel band, and in the PP, PQ, PR, RP, RQ, and RR branches of the nu5 perpendicular band. These lines with J values ranging from 1 to 23 and K from 0 to 9 (K View Article and Find Full Text PDF

Absolute Absorption Intensities in the Fundamental nu2 and nu5 Bands of 12CH3F.

The absolute strengths of 93 lines belonging to the nu2 and nu5 bands of methyl fluoride were measured in the range of 1416-1503 cm-1 using a tunable diode-laser (TDL) spectrometer. These experimental line intensities were obtained from the equivalent width method. The intensities were analyzed within a dyad system, required to account properly for the strong Coriolis coupling between nu2 and nu5.

Nitrogen Broadening of Acetylene Lines in the nu5 Band at Low Temperature.

N2-broadening coefficients have been measured for 22 lines of C2H2 at 173.4 K in the P and R branches of the nu5 band, using a tunable diode-laser spectrometer. The lines with J values ranging from 1 to 29 are located in the spectral range of 661-762 cm-1.

Correlated and Noncorrelated Lineshape Models under Small Lineshift Condition: Analysis of Self-Perturbed CH3D.

The 14 transitions belonging to the P branch of the nu3 band of CH3D, near 1250 cm-1, have been measured with a tunable diode-laser spectrometer. These lines, recorded at a total pressure ranging from 1 to 60 mbar, have been analyzed by means of soft and hard collision lineshape models. We emphasize the equivalence between the correlated and noncorrelated profiles, when the collisional lineshift may be neglected.

Line-Mixing Effects in Q Branches of CO2.

A theoretical model based on the energy corrected sudden (ECS) approximation is used in order to account for line-mixing effects in Delta left and right arrow Pi infrared Q branches of 12C16O2. Its quality is demonstrated by comparisons with numerous laboratory spectra of CO2-He and CO2-N2 mixtures: three Q branches in the 4 and 17 μm regions are investigated at room temperature in a wide pressure range. The influence of mixing between Q(J) lines associated with odd and even values of the rotational quantum number J is demonstrated and analyzed in detail.

Diode-Laser Measurements of He-Broadening Coefficients in the nu6 Band of 12CH3F.

He-broadening coefficients are measured for 28 lines of 12CH3F in the RQ0 (Ki = 0, DeltaK = 1, DeltaJ = 0) and RQ6 (Ki = 6, DeltaK = 1, DeltaJ = 0) branches of the nu6 band, using a tunable diode laser spectrometer. The collisional widths obtained by fitting Rautian profiles to the measured shapes of the lines are slightly larger than those derived from Voigt profiles. The broadening coefficients for the lines belonging to the same low J transitions are significantly greater in the RQ0 branch than in the RQ6 branch.