New High-Resolution Analysis of the nu(3) Band of the (15)N(16)O(2) Isotopomer of Nitrogen Dioxide by Fourier Transform Spectroscopy

New high-resolution Fourier transform absorption spectra of an (15)N(16)O(2) isotopic sample of nitrogen dioxide were recorded at the University of Bremen in the 6.3-μm region. Starting from the results of a previous study [Y. Hamada, J. Mol. Struct. 242, 367-377 (1991)], a new and more extended analysis of the nu(3) band located at 1582.1039 cm(-1) has been performed. The spin-rotation energy levels were satisfactorily reproduced using a theoretical model which takes into account both the Coriolis interactions between the spin-rotation energy levels of the (001) vibrational state with those of the (020) and (100) states and the spin-rotation resonances within each of the NO(2) vibrational states. Precise vibrational energies and rotational, spin-rotation, and coupling constants were obtained in this way for the first triad of (15)N(16)O(2) interacting states {(020), (100), (001)}. Finally, a comprehensive list of line positions and line intensities of the {nu(1), 2nu(2), nu(3)} interacting bands of (15)N(16)O(2) was generated, using for the line intensities the transition moment operators which were obtained previously for the main isotopic species. Copyright 2000 Academic Press.     

High-Resolution Absorption Spectroscopy of the 3nu(1) and 3nu(1) + nu(3) Bands of Propyne

The 3nu(1) and 3nu(1) + nu(3) bands of propyne have been recorded at Doppler-limited resolution by Fourier transform spectroscopy and intracavity laser absorption spectroscopy, respectively. The two bands show a mostly unperturbed J rotational structure for each individual K subband. However, as a rule the K structure ordering is perturbed in overtone transitions of propyne and different effective parameters associated with each K subband have been determined. From the vibrational energy levels, a value of -6.6 cm(-1) has been obtained for the x(13) cross anharmonicity in perfect agreement with the origins of the nu(1) + nu(3) and 2nu(1) + nu(3) combination bands estimated from the FTIR spectrum. Hot bands from the v(9) = 1 and v(10) = 1 levels associated with the 3nu(1) + nu(3) combination band have been partly rotationally analyzed and the retrieved values of x(39) and x(3,10) are in good agreement with literature values. Finally, the 4nu(1) + nu(9) - nu(9) band centered at 12 636.6 cm(-1) has been recorded by ICLAS. The red shift of this hot band relative to 4nu(1) and the DeltaB(v) value are discussed in relation to the anharmonic interaction between the 4nu(1) and 3nu(1) + nu(3) + nu(5) levels. Copyright 2000 Academic Press.     

High-Resolution Fourier Transform and Diode-Laser Spectroscopy of the nu(6) Fundamental of C(2)F(6) and Associated Hot Bands

High-resolution infrared spectra of the nu(6) (713 cm(-1)) band region of C(2)F(6) vapor have been recorded at several temperatures. Spectra at 77, 200, and 300 K were recorded using a Fourier transform spectrometer with unapodized resolutions of 0.0018 cm(-1) (200 and 300 K) and 0.008 cm(-1) (77 K). Spectra with rotational temperatures in the range 5-50 K were recorded in a supersonic jet using diode-laser absorption spectroscopy. The nu(6) band contains two clear sequences of hot-bands: one arises from the nu(4) torsional vibration at 67.5 cm(-1); the other, shorter, weaker progression is built on the doubly degenerate nu(9) vibration at 220 cm(-1). They lie to high and low wavenumbers of the fundamental band, respectively. Eleven series were assigned and fitted to these hot bands. A perturbed series in the nu(4) sequence is considered, by analogy with the infrared spectrum of C(2)H(6) vapor, to be caused by an xy-Coriolis interaction either between 5nu(4) and nu(9) + 2nu(4) in the ground state or, in the upper state, nu(6) + 5nu(4) with nu(6) + nu(9) + 2nu(4) or nu(6) + 5nu(4) with 2nu(8). One further series resolved only in the jet spectrum and lying very close to the fundamental is almost certainly due to the nu(6) fundamental of the isotopomer (13)C(12)CF(6). Copyright 2000 Academic Press.     

High-Resolution Laser Photoacoustic Spectroscopy of HSiF(3): The 5nu(1) and 6nu(1) Overtone Bands

A spectrum of HSiF(3) has been recorded at room temperature with a gas pressure of 20-50 Torr in the near-infrared region. A laser photoacoustic spectrometer consisting of a longitudinal resonant cell coupled to a titanium:sapphire ring laser was employed. The 5nu(1) and 6nu(1) overtone bands of H(28)SiF(3) associated with the Si-H stretching have been observed at high resolution (3 x 10(-2) cm(-1)) in the regions 10 900-10 960 and 12 875-12 925 cm(-1), respectively. About 450 lines of the 5nu(1)-0 band have been assigned (J 相似文献   

Fourier Transform Spectroscopy of the O(2) Herzberg Bands

From absorption spectra obtained at high resolution by coupling a Fourier transform spectrometer to a long-path multiple reflection cell [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] the intensities of the O(2) Herzberg bands (A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), A'( 3)Delta(u)-X(3)Sigma(-)(g)) have been studied at ambient temperature. The integrated cross section values are given for the lines of the (v'-0) bands in the A(3)Sigma(+)(u)-X(3)Sigma(-)(g), c(1)Sigma(-)(u)-X(3)Sigma(-)(g), and A'( 3)Delta(u)-X(3)Sigma(-)(g) transitions with v' = 0-11, v' = 2-19, and v' = 2-12, respectively. The band oscillator strengths have been deduced and transition moments have been calculated. The total absorption values in the region of the Herzberg bands together with the photoabsorption values determined previously above the dissociation limit can be modeled by a single curve, in agreement with the continuity relationship of the cross sections through the dissociation limit. Copyright 2000 Academic Press.     

Fourier Transform Infrared Spectra of CH(2)DF: The nu(5) and nu(6) Bands

Results of a high-resolution infrared study of the spectroscopy of monodeuterated methyl fluoride, CH(2)DF, are reported for the first time. Spectra ranging from 500 to 3300 cm(-1) have been obtained and cover all the fundamental bands at resolutions down to 0.005 cm(-1). The two lowest energy fundamentals, the nu(5) and nu(6) bands, have been analyzed in detail. Since the molecule has C(s) symmetry, in principle both these bands are AB hybrids, since they belong to the irreducible representation A'. However, it was found that both are almost pure A-type bands. A total of 597 A-type lines of the nu(5) band and 619 A-type lines of the nu(6) band have been assigned. Vibrational and rotational spectroscopic constants have been determined by least-squares fitting to the data. An improved band center for nu(7) is also reported. Copyright 2001 Academic Press.     

13C(16)O(2): Global Treatment of Vibrational-Rotational Spectra and First Observation of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) Absorption Bands

The effective operator approach is applied to the calculation of both line positions and line intensities of the (13)C(16)O(2) molecule. About 11 000 observed line positions of (13)C(16)O(2) selected from the literature have been used to derive 84 parameters of a reduced effective Hamiltonian globally describing all known vibrational-rotational energy levels in the ground electronic state. The standard deviation of the fit is 0.0015 cm(-1). The eigenfunctions of this effective Hamiltonian have then been used in fittings of parameters of an effective dipole-moment operator to more than 600 observed line intensities of the cold and hot bands covering the nu(2) and 3nu(2) regions. The standard deviations of the fits are 3.2 and 12.0% for these regions, respectively. The quality of the fittings and the extrapolation properties of the fitted parameters are discussed. A comparison of calculated line parameters with those provided by the HITRAN database is given. Finally, the first observations of the 2nu(1) + 5nu(3) and nu(1) + 2nu(2) + 5nu(3) absorption bands by means of photoacoustic spectroscopy (PAS) is presented. The deviations of predicted line positions from observed ones is found to be less than 0.1 cm(-1), and most of them lie within the experimental accuracy (0.007 cm(-1)) once the observed line positions are included in the global fit. Copyright 2000 Academic Press.     

High Resolution FTIR Spectroscopy of DCCCl: Anharmonic Resonances in the nu(1) and nu(2) Bands

High-resolution infrared spectra of the nu(1) and nu(2) bands of DCCCl were observed using Bruker IFS 120HR Fourier transform spectrometers at resolutions of 0.0044 and 0.0035 cm(-1), respectively. For the DCC(35)Cl isotopomer, the nu(1) as well as the nu(2) band was found to be heavily perturbed. Detailed analyses revealed that the nu(1) state is in resonance with the l=0 substate of the nu(3)+4nu(4) state and that the nu(2) state is in resonance with the l=0 substate of the nu(3)+4nu(5) state. The rotational constants played a key role in identifying the perturbing states. In contrast, for the DCC(37)Cl isotopomer, the rotational structures of the nu(1) and nu(2) states are almost regular but slightly perturbed by interactions with the nu(3)+4nu(4) and nu(3)+4nu(5) states, respectively. The constants of resonances as well as the molecular constants for the nu(1), nu(2), nu(3)+4nu(4) and nu(3)+4nu(5) states were determined. Copyright 2001 Academic Press.     

High-Resolution Spectroscopy and Analysis of the nu(3) and nu(4) Fundamentals of Monoisotopic (70)GeF(4)

The first high-resolution study on germanium tetrafluoride is reported. We used a monoisotopic sample of (70)GeF(4). The FTIR spectra of the two infrared active fundamentals, namely the nu(4) (bending) and nu(3) (stretching) modes, were recorded at a temperature of ca. 210 K and a resolution (1/maximum optical path difference) of 0.0031 and 0.0023 cm(-1), respectively. These spectra were analyzed using the STDS software developed in Dijon. In both cases, we obtained a fit with a root mean square better than 1x10(-3) cm(-1). Both bands show very regular structures with no detectable perturbation. Copyright 2001 Academic Press.     

Analysis of the nu(12) Band of Ethylene-(13)C(2) by High-Resolution FTIR Spectroscopy

The Fourier transform infrared (FTIR) spectrum of the nu(12) fundamental band of ethylene-(13)C(2) ((13)C(2)H(4)) was recorded with an unapodized resolution of 0.004 cm(-1) in the frequency range from 1380 to 1500 cm(-1). Rovibrational constants for the upper state (nu(12)=1) up to five quartic and three sextic centrifugal distortion terms were derived for the first time by assigning and fitting a total of 1177 infrared transitions using a Watson's A-reduced Hamiltonian in the I(r) representation. The rms deviation of the fit was 0.00045 cm(-1). The ground state rovibrational constants were also determined for the first time by a fit of 738 combination differences from the present infrared measurements, with a rms deviation of 0.00060 cm(-1). The A-type nu(12) band with a band center at 1436.65411+/-0.00005 cm(-1) was found to be relatively free from local frequency perturbations. The inertial defect Delta(12) was found to be 0.24300+/-0.00002 u?(2). Copyright 2001 Academic Press.     

High-Resolution Infrared Spectrum of BrCN in the nu(2) and nu(1)/2nu(2) Regions

The vibrational excitations of bent triatomic molecules, including both bending and stretching vibrations, are studied in the framework of the U(4) algebra. For the bent triatomic molecules H(2)O and H(2)S, the highly excited vibrational levels (up to 14) are obtained using the U(4) algebraic approach. We have found that the spectra are made up of clustering structure. The number of levels in one cluster depends on the total quanta of stretching and bending. In addition, some other properties are also discussed. Copyright 2000 Academic Press.     

Absolute Intensities of the nu(1) and nu(3) Bands of (16)O(3)

New experimental data on the nu(1) and nu(3) bands of (16)O(3) improving the value of absolute line intensities have been obtained. The intensities of 295 lines have been measured with an average accuracy between 2.5% and 3% and the rotational expansion of the transition moment operators for the nu(1) and nu(3) bands has been deduced. Finally, a complete listing of line intensities has been computed with an intensity cutoff of 1x10(-25) cm(-1)/molecule cm(-2). Copyright 2001 Academic Press.     

High-Resolution Infrared Spectrum of CD(3)CN: Analysis of the Interacting nu(3) and nu(6) Bands and Evaluation of the A(0) Constant

The infrared spectrum in the range 900-1230 cm(-1) including the fundamental bands nu(3) and nu(6) of CD(3)CN has been studied. The resolution attained was 0.0025 cm(-1) in the measurement on the Bruker 120 HR Fourier spectrometer in Oulu. About 4000 lines were assigned in the nu(6) band. For the weak nu(3) band, which has not been observed earlier directly, we were able to assign 206 lines in three subbands K=8-10. These lines become detectable due to the strong nu(3)/nu(6) Coriolis resonance. There is also an l(1,-2) resonance between nu(3) and nu(6), which made it possible to obtain a value 2.647721(50) cm(-1) for the axial rotational constant A(0), when D(0)(K) from force field calculations was applied. Different types of resonances with the overtone 3nu(8) and the combinations nu(4)+nu(8) and nu(7)+nu(8) were observed. A fit with a standard deviation of 0.0019 cm(-1) was attained by using a model of 10 different resonances. Copyright 2001 Academic Press.     

High-Resolution Infrared Study of the nu(7), nu(8), and nu(15) Bands and Millimeter-Wave Investigation of the v(8) = 1 State of CF(2)Cl-CH(3)

High-resolution (Deltavarsigma = 2.3 and 2.9 x 10(-3) cm(-1)) FTIR spectra of natural and (35)Cl monoisotopic CH(3)CF(2)Cl have been recorded at -70 degrees C in the 600-1400 cm(-1) range. The bands nu(7), nu(8), and nu(15) have been rotationally analyzed for both isotopic varieties. With the help of predictions based on nu(8) parameters, the millimeter-wave spectrum of the (35)Cl species in the v(8) = 1 state has been observed and jointly fitted with the IR data. Only a small number of local perturbations have been detected in the spectra. Altogether more than 8000 IR transitions have been fitted with an experimental precision of ca. 3 x 10(-4) cm(-1). Copyright 2000 Academic Press.     

High-Resolution Survey of the Visible Spectrum of NiF by Fourier Transform Spectroscopy

High-resolution spectra of NiF have been recorded in emission by Fourier transform spectroscopy using a very stable discharge source. The 0-0 bands of 14 electronic transitions have been studied, 6 of them for the first time. This work confirms the presence of 5 low-lying spin components X²Π_3/2, [0.25]²Σ⁺, [0.83]A²Δ_5/2, [1.5]B²Σ⁺, and [2.2]A²Δ_3/2 as known from previous laser-induced fluorescence experiments. Eight electronic states are now identified in the 18 000-24 000 cm⁻¹ range above the ground X²Π_3/2 state. Electronic assignments for these excited states are not always obvious because of violations of the selection rules and unusual fine structure parameters. We think that some of the upper states are spin components of quartet states. In such a congested spectrum, high-resolution spectra are best analyzed in conjunction with an energy level diagram constructed mainly by dispersed low resolution laser-induced fluorescence.     

Fourier Transform Spectroscopy of the O(2) Herzberg Bands. III. Absorption Cross Sections of the Collision-Induced Bands and of the Herzberg Continuum

Absorption spectra of molecular oxygen were measured in the laboratory under temperature and pressure conditions prevailing in the Earth's atmosphere. Spectra of pure O(2), O(2) + N(2), and O(2) + Ar were recorded in the 41 700 to 33 000 cm(-1) region (240-300 nm) at a maximal optical path difference of 0.45 cm using a Fourier transform spectrometer and a multiple reflection gas cell. The different components of the spectra, namely the discrete bands of the three Herzberg systems, the Herzberg continuum, and the collision-induced diffuse Wulf bands, were separated. The contribution of the Herzberg bands was first subtracted using the line parameters determined previously [A. Jenouvrier, M.-F. Mérienne, B. Coquart, M. Carleer, S. Fally, A. C. Vandaele, C. Hermans, and R. Colin, J. Mol. Spectrosc. 198, 136-162 (1999)] from high-resolution data. Spectra recorded at various pressures then made it possible to determine by linear regression the intensity of the Wulf bands and the Herzberg continuum. The characteristics of the Wulf bands have been investigated in details: vibrational analysis, pressure effect, foreign gas effect, and a simulated spectrum are reported. The Herzberg continuum cross section is determined below the dissociation limit. A comparison with literature data is given. The new O(2) absorption cross sections and O(2)-O(2) collision-induced absorption cross sections are useful in connection with atmospheric measurements of ozone and other trace gases in the UV spectral region. Copyright 2000 Academic Press.     

Measurements of (18)O-Enriched Ozone Isotopomer Abundances Using High-Resolution Fourier Transform Far-IR Spectroscopy

The distribution of ozone isotopomers in ozone mixtures produced by electric discharge in mixtures of (16)O(2) and (18)O(2) at 77 K was measured by high-resolution FTIR spectroscopy. It was of key importance to assess not only the total amount of isotopomers of a certain mass but also the relative amounts of corresponding asymmetric and symmetric ozone species of the same mass given as the ratios [(16)O(16)O(18)O]/[(16)O(18)O(16)O] and [(16)O(18)O(18)O]/[(18)O(16)O(18)O]. For many purposes both ratios have been assumed to have the statistical value 2.00. Pure rotational spectra in the far-IR region (30-100 cm(-1)) were recorded for three different (18)O-enriched ozone mixtures, all at 0.00185 cm(-1) resolution. All the spectra were corrected for thermal emission. Linestrengths for individual lines in a particular spectrum were measured by means of a fitting technique taking into account contributions from all other lines in the spectrum. For this purpose theoretical linestrengths for all six ozone species containing (16)O and (18)O obtained from a quantum-number-dependent dipole operator were used. The ratios between observed and theoretical linestrengths were used to determine the abundances of individual isotopomers in a particular ozone mixture. For one of the ozone samples the abundances of all six ozone species were determined within 1% relative uncertainty. For the three ozone mixtures studied, the ratio between asymmetric and symmetric species of mono-(18)O ozone were determined to 1.99(2), 2.01(2), and 2.10(6). The ratio between asymmetric and symmetric species of di-(18)O ozone were determined to 2.51(4), 2.42(10), and 2.46(3). Copyright 2000 Academic Press.     

High-Resolution Spectrum and Rovibrational Analysis of the nu(2)/nu(5) Dyad of D(3)SiF near 700 cm(-1)

The nu(2) (A(1), 710.157 cm(-1)) and nu(5) (E, 701.717 cm(-1)) fundamental bands of D(3)(28)SiF have been studied by FTIR spectroscopy with a resolution of 2.4 x 10(-3) cm(-1). We assigned 1648 lines for the parallel band (J(max) = 50, K(max) = 21), 4279 for the perpendicular band (J(max) = 52, K(max) = 27), and in addition 671 perturbation-allowed transitions (J(max) = 50, K(max) = 12). The nearly degenerate v(2) = 1 and v(5) = 1 states are linked by (DeltaK = +/-1, Deltal = +/-1) and (DeltaK = +/-2, Deltal = -/+1) interactions, while the l(5) = +/-1 levels of nu(5) interact also by l(2, -1), l(2, 2), and l(2, -4) interactions. The first model with 36 free parameters, taking into account all these resonances through a nonlinear least-squares program, gave standard deviations of 1.56 x 10(-4) cm(-1) for 5997 nonzero-weighted IR data and 138 kHz for 8 MW data from the literature. The second model, in which the main Coriolis term was constrained to a force field value, used 37 parameters and gave similar standard deviations. A new determination of the A(0) and D(0)(K) ground state parameters was performed by two methods: either using differences between "forbidden" transitions differing by 3 in K or letting A(0) and D(0)(K) free in the global fit. The values obtained are fully compatible with those obtained previously by the "loop method." Copyright 2000 Academic Press.     

High-Resolution Fourier Transform Spectra of HDSe: The Interacting States (v(1) v(2) v(3))/(v(1) +/- 1 v(2) -/+ 2 v(3)) with 2v(1) + v(2) = 1, 2, 3, and 4

For the first time, high-resolution Fourier transform spectra of HDSe in the region of the three polyads, nu(1)/2nu(2), nu(1) + nu(2)/3nu(2), and 2nu(1)/nu(1) + 2nu(2)/nu(2) + nu(3), have been recorded and analyzed. Combined with an earlier investigation of the nu(2) band, and including estimates for the unobserved "dark" 4nu(2) band, these levels were subjected to a "Global Fit," which makes use of relations between parameters within the different polyads. Since there are five isotopic species present in natural HD(M)Se (M = 82, 80, 78, 77, 76), altogether 34 vibration-rotation bands have been studied in the present contribution. The parameters determined by the Global Fit reproduce upper vibrational-rotational energies of all these bands with accuracies close to experimental precision. Copyright 2000 Academic Press.     

High-Resolution Infrared Spectra in the C-H Region of CH2F2: The nu6 and 2nu2 Bands

High-resolution, infrared absorption spectra of the nu6 (asymmetric C-H stretch) and 2nu2 (H-C-H symmetric bend overtone) bands of jet-cooled CH2F2 are reported with a sub-Doppler resolution of approximately 0.002 cm-1. More than 600 transitions were observed in the range of 3002-3036 cm-1, of which 268 were assigned the nu6 fundamental and 184 were assigned to the 2nu2 overtone. A fit of the nu6 band to the A-reduced Watson Hamiltonian yielded eight effective constants including nu0 = 3014.0503(1), A' = 1.62868(4), B' = 0.354165(5), and C' = 0.308852(3) cm-1. Similarly, the weaker 2nu2 band was fit to seven parameters including nu0 = 3026.2297(2), and A' = 1.63396(6), B' = 0.35367(1), and C' = 0.31183(1) cm-1. Numbers in parentheses are two standard deviations in units of the last digit. Anomalous values of the A rotational constant and the DeltaK centrifugal distortion constant are attributed to an a-axis Coriolis interaction between the 2nu2 and nu6 bands. The relative intensity of the 2nu2 band is used to estimate the stretch-bend anharmonic interaction with nu1. Copyright 1999 Academic Press.