High-Resolution Analysis of the ν6, ν17, and ν21 Bands of Dimethyl Ether

The ν₆, ν₁₇, and ν₂₁ fundamental bands of dimethyl ether have been assigned and rotationally analyzed. The spectra used were recorded at 0.005 cm⁻¹ spectral resolution with a Fourier-transform spectrometer coupled to a supersonic molecular beam leading to a rotational temperature of about 70 K. The ν₆ and ν₂₁ bands do not seem to be perturbed and the analysis of the rotational structure leads to band centers located at 933.906 6(9) and 1 103.951(1) cm⁻¹, respectively, and to accurate rotational and centrifugal distortion constants. For the ν₁₇ band at 2817.385(2) cm⁻¹, only the P and R branches could be assigned.     

A High-Resolution FT-IR Study of the Fundamental Bands ν6, ν10, and ν11 of trans-Glyoxal

The high-resolution Fourier transform infrared spectrum of trans-glyoxal in the gas phase has been recorded in the spectral regions 700-900 cm⁻¹, 1200-1400 cm⁻¹, and 1600-1800 cm⁻¹ with a resolution ranging from 0.0020 to 0.0025 cm⁻¹. The spectrum displays extensive rotational structures which are assigned to the three fundamental bands ν₆ (A_u, 801.5 cm⁻¹), ν₁₀ (B_u, 1732.1 cm⁻¹), and ν₁₁ (B_u, 1312.5 cm⁻¹). A total of ca. 5000 absorption lines have been assigned to these three bands. A simultaneous ground state combination difference analysis of all three bands yields improved ground state spectroscopic constants for trans-glyoxal. Furthermore, a number of spectroscopic constants for the ν₆ and ν₁₁ levels have been determined for the first time.     

Observation of simultaneous ν1(SF6) + ν3(NF3) and ν2(SF6) + ν3(NF3) transitions enhanced by the resonance dipole-dipole interaction with the ν1 + ν3 and ν2 + ν3 states of the SF6 molecule

IR spectra of the solution of SF₆ molecules in liquid NF₃ at 84 K have been recorded. In a solvent transmission window of 1500–1750 cm⁻¹, two wide absorption bands with pronounced peaks in the high-frequency part are observed. The profile of these bands is explained by the influence of the resonance dipole-dipole (RDD) interaction of the states of the simultaneous transition ν₁(SF₆) + ν₃(NF₃) and ν₂(SF₆) + ν₃(NF₃) with the states (ν₁ + ν₃) and (ν₂ + ν₃) of the SF₆ molecules, respectively. The use of three isotopic modifications ³²SF₆, ³³SF₆, and ³⁴SF₆ has allowed us to vary the resonance detuning and thus to change the strength of the RDD interaction. With the liquid near the melting point being represented as a close-packed cubic crystal, the profile was calculated and its spectral characteristics were determined. The frequencies of the main peaks coincide with the experimental values accurate to the error.     

On the Study of Resonance Interactions and Splittings in the PH3 Molecule: ν1, ν3, ν2+ν4, and 2ν4 Bands

The high-resolution (0.005 cm⁻¹) Fourier transform infrared spectrum of PH₃ is recorded and analyzed in the region of the fundamental stretching bands, ν₁ and ν₃. The ν₂+ν₄ and 2ν₄ bands are taken into account also. Experimental transitions are assigned to the ν₁, ν₃, ν₂+ν₄, and 2ν₄ bands with the maximum value of quantum number J equal to 15, 15, 13, and 15, respectively. a₁-a₂ splittings are observed and described up to the value of quantum number K equal to 10. The analysis of a₁/a₂ splittings is fulfilled with a Hamiltonian model which takes into account numerous resonance interactions among all the upper vibrational states.     

Analysis of ν2, ν4 Infrared Hot Bands of SO3: Resolution of the Puzzle of the ν1 CARS Spectrum

Further analysis of the high-resolution (0.0015 cm⁻¹) infrared spectrum of ³²S¹⁶O₃ has led to the assignment of more than 3100 hot band transitions from the ν₂ and ν₄ levels to the states 2ν₂ (l=0), ν₂+ν₄ (l=±1), and 2ν₄ (l=0,±2). These levels are strongly coupled via Fermi resonance and indirect Coriolis interactions to the ν₁ levels, which are IR-inaccessible from the ground state. The unraveling of these interactions has allowed the solution of the unusual and complicated structure of the ν₁ CARS spectrum. This has been accomplished by locating over 400 hot-band transitions to levels that contain at least 10% ν₁ character. The complex CARS spectrum results from a large number of avoided energy-level crossings between these states. Accurate rovibrational constants are deduced for all the mixed states for the first time, leading to deperturbed values of 1064.924(11), 0.000 840 93(64), and 0.000 418 19(58) cm⁻¹ for ν₁, α₁^B, and α₁^C, respectively. The uncertainties in the last digits are shown in parentheses and represent two standard deviations. In addition, new values for some of the anharmonicity constants have been obtained. Highly accurate values for the equilibrium rotational constants B_e and C_e are deduced, yielding independent, nearly identical values for the SO r_e bond length of 141.734 03(13) and 141.732 54(18) pm, respectively.     

The ν1, ν2, and ν3 Band Systems of 3-Isocyano-2-propynenitrile (NCCCNC): Comparison with the ν4 System of Dicyanoacetylene

The hot bands in the ν₁, ν₂, and ν₃ band systems of NC-CC-NC (3-isocyano-2-propynenitrile) have been investigated and transitions from nv₉-levels with n up to 4 have been identified. Two weak bands have also been observed in the gas phase infrared spectrum at 2157 and 2410 cm⁻¹, of which the latter is probably 2v₄. A preliminary investigation of some analogous hot bands in the v₄ band system of the related molecule NC-CC-CN (dicyanoacetylene) is also reported.     

The ν1 and 3ν1 bands of HNCO

The infrared absorption of HNCO has been measured in the region of the NH stretching fundamental and in that of the second overtone. The results for the excited states are (in cm^?1):

     

8.

The (ν₁, ν₄, ν₂+ν₃, ν₃+ν₅) Polyad of D₃SiF around 1600 cm, Studied by High-Resolution FTIR Spectroscopy     

N. Boulaftali  N. Ben Sari-Zizi  H. Najib  G. GranerH. Bürger  E.B. MkadmiP. Pracna 《Journal of Molecular Spectroscopy》2002,214(1):35-51

The ν₁ (A₁, 1578.31 cm⁻¹)/ν₄(E, 1615.17 cm⁻¹) Si-D stretching dyad of D₃SiF has been studied by FTIR spectroscopy with a resolution of 2.4×10⁻³ cm⁻¹. Only weak interactions of Coriolis (ΔK=±1, Δ?=±1) and α resonance (ΔK=±2, Δ?=?1) type between ν₁ and ν₄, and of ? (2,−4) type within ν₄, were revealed. However, the v₁=1 and v₄=1 levels were found to be severely perturbed by the v₃=v₅=1 (E, 1590.37 cm⁻¹) and v₂=v₃=1 (A₁, 1604.25 cm⁻¹) states. These perturbations are observable only near level crossings involving strong Coriolis and α interactions. The energy structure within these perturbers is severely complicated by strong Coriolis and α resonances and by ? (2, 2), ? (2,−1), and ? (2,−4) interactions as already revealed by the ν₂(A₁, 710.16 cm⁻¹) and ν₅ (E, 701.72 cm⁻¹) fundamentals. Interactions of the perturbing states with the ν₁/ν₄ dyad are particularly evident in local crossings. In total, 12 transitions belonging to the dark states and 68 perturbation-allowed transitions within the ν₁/ν₄ dyad have been detected among the more than 5000 transitions that have been assigned for the ν₁/ν₄ dyad, with J_max and K_max of 50 and 30, respectively. Altogether about 85% of the assigned transitions were fitted with a standard deviation of 0.221×10⁻³ cm⁻¹, leading to 61 parameters of the interacting polyad.     

9.

The ν₁, ν₂, and ν₃ bands of carbonyl chlorofluoride (COFCl) at 5.3, 9.1, and 13.1 μm: position and intensity parameters and their use for atmospheric studies     

Agnes Perrin  Jean Demaison 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(8):1266-1279

A list of line positions and, for the first time, of line intensities was generated for the ν₁, ν₂, and ν₃ fundamental bands of the ¹²C¹⁶OF³⁵Cl and ¹²C¹⁶OF³⁷Cl isotopologs of carbonyl chlorofluoride, located at 5.3, 9.1, and 13.1 μm, respectively. In addition, for the most abundant isotopolog (¹²C¹⁶OF³⁵Cl) this linelist includes also the contributions from the first two associated hot bands. The parameters included in this database were generated by combining the results of previous experimental analyses and ab initio calculations [Perrin A, Flaud JM, Bürger H, Pawelke G, Sander S, Willner H. First high resolution analysis of the six fundamental bands ν₁, ν₂, ν₃, ν₄, ν₅ and ν₆ of COF³⁵Cl in the 340 to 2000 cm⁻¹ region. J Mol Spectrosc 2001;209:122-232; Demaison J, Perrin A, Bürger H. Ab initio anharmonic force field and equilibrium structure of carbonyl chlorofluoride. J Mol Spectrosc 2003;221:47-56]. For the purpose of the present work, a partial re-investigation of the ν₁ of COF³⁵Cl was performed, together with the first identification of the ν₂ band of COF³⁷Cl.These parameters were generated in order to improve the quality of remote sensing of the atmosphere in the mid-IR. Analyses of atmospheric solar occultation spectra measured by the JPL MkIV interferometer show that the new linelist not only improves the quality of retrievals of COFCl, but also of several other gases whose absorptions overlap those of COFCl.     

10.

Search for ν_μ and ν_τ supernova neutrinos with massive liquid-scintillation detectors     

P. Antonioli  W. Fulgione  P. Galeotti  L. Panaro 《Il Nuovo Cimento C》1991,14(6):631-637

Summary In this paper we have estimated the sensitivity of a large-mass liquid-scintillation detector to search for supernova neutrinos of different flavours. Events produced by ν_μ and ν_τ interactions can be identified by looking at the distorsion in the neutrino energy spectrum. We have shown here that, overlapped to the main energy distribution produced by interactions with protons a peak at 15.11 MeV (due to the de-excitation of¹²C^* nuclei excited by neutral-current neutrino interactions) gives a possible signature of these neutrino flavours. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

11.

First Gas Phase Infrared Spectroscopy of F₂BOH: High-Resolution Study of the ν₈ and ν₉ Bands     

D. ColletA. Perrin  H. BürgerJ.-M. Flaud 《Journal of Molecular Spectroscopy》2002,212(1):118-124

For the first time the infrared spectrum of F₂BOH in the gas phase has been observed. After optimizing the conditions for the synthesis we have been able to obtain high-resolution (2.4-3.3×10⁻³ cm⁻¹) infrared spectra in the ν₈, ν₉, and ν₄ regions with both natural and ¹¹B monoisotopic material. Analyses of the ν₈ (BF₂ out-of-plane bending) and ν₉ (OH torsion) fundamental bands located at 684.160 and 522.870 cm⁻¹, respectively, for F₂¹¹BOH are presented here. Existing J≤10 microwave transitions were combined with novel ground state combination differences with J≤55 formed from A-type (ν₄) and C-type (ν₈, ν₉) bands to yield substantially improved and extended ground state parameters. Using a standard Watson-type Hamiltonian, 8¹ and 9¹ upper state parameters were obtained by fitting about 2000 lines each with σ(fit) ca. 3.5×10⁻⁴ cm⁻¹. The 8¹ and 9¹ states both appear to be unperturbed, as indicated by the agreement of the ground and excited state centrifugal distortion constants.     

12.

Water Spectra in the Region 4200-6250 cm, Extended Analysis of ν₁+ν₂, ν₂+ν₃, and 3ν₂ Bands and Confirmation of Highly Excited States from Flame Spectra and from Atmospheric Long-Path Observations     

S.N. Mikhailenko  VL.G. TyuterevV.I. Starikov  K.K. AlbertB.P. Winnewisser  M. Winnewisser  G. MellauC. Camy-Peyret  R. LanquetinJ.-M. Flaud  J.W. Brault 《Journal of Molecular Spectroscopy》2002,213(2):91-121

Water vapor infrared spectra have been recorded at room temperature in the range 4200-6250 cm⁻¹ at resolutions (FWHM) between 0.0053 and 0.0080 cm⁻¹. The use of a White-type multireflection cell made large pressure × pathlength products possible up to 31.27 mbar×288.5 m. The high signal-to-noise ratio allowed us to observe lines with intensities as small as 10⁻²⁶ cm⁻¹/molecule cm⁻² at T=296 K. Among about 5100 recorded water lines, about half of which are reported for the first time, 2351 lines have been assigned to the second triad of H₂¹⁶O (bands ν₁+ν₂, ν₂+ν₃, and 3ν₂). This has allowed the determination of line positions and corresponding upper rovibrational states with considerably improved accuracy. The assignments of certain highly excited states have been confirmed by the analysis of flame spectra and hot emission spectra. New values of effective Hamiltonian parameters for the upper states {(110), (030), (011)} have been determined. The generating function model was used in the data reduction to account for the anomalously strong centrifugal distortion of the rovibrational levels and resonance interactions. The RMS standard deviation of the least-squares fit of the assigned H₂O data was 5×10⁻³ cm⁻¹ for line positions and 7×10⁻³ cm⁻¹ for energy levels up to J_max=20 and K_a(max)=13. Particular attention was paid to water lines in the transparency window 4200-5000 cm⁻¹, in which existing databases are not sufficient. In this region, 1395 lines of four isotopic species of water have been recorded and over 900 accurate line positions of nine bands of H₂¹⁶O (ν₁, ν₃, 2ν₂, ν₁+ν₂, ν₂+ν₃, 3ν₂, 4ν₂−ν₂, 2ν₂+ν₃−ν₂, ν₁+2ν₂−ν₂) are reported in this range. A comparison of laboratory spectra with long path atmospheric spectra (20 km slant path in the mountains) in this region shows that many lines missing from available spectroscopic compilations (or considerably shifted compared to observations) are important for a proper interpretation of atmospheric observations. A comparison of the observed data with the best available predictions from the molecular electronic potential energy surface is discussed.     

13.

New High-Resolution Analysis of the ν₇ and ν₉ Fundamental Bands of trans-Formic Acid by Fourier Transform Infrared and Millimeter-Wave Spectroscopy     

A PerrinJ.-M Flaud  B BakriJ Demaison  O BaskakovS.V Sirota  M HermanJ.Vander Auwera 《Journal of Molecular Spectroscopy》2002,216(2):203-213

The high-resolution (0.002 cm⁻¹) spectrum of the ν₇ (OCO scissor mode) and ν₉ (COH torsion mode) fundamental bands of trans-formic acid (HCOOH) at 15.8 μm was recorded by Fourier transform infrared spectroscopy. In addition, millimeter-wave transitions within the 7¹ and 9¹ vibrational states were measured in the spectral range 340-600 GHz. Using these new experimental data, an extensive analysis of the ν₇ and ν₉ bands was performed. The model we have used accounts for the strong A- and B-type Coriolis interactions which couple the 7¹ and 9¹ vibrational states and which were already pointed out in the literature [J. C. Deroche, J. Kauppinen and E. Kyrö, J. Mol. Spectrosc.78, 379-394 (1979); E. Willemot, J. Mol. Spectrosc.120, 246-275 (1986)]. The observed levels are fit to within the experimental accuracy leading to the determination of a precise set of band centers of ν₇ and ν₉ at 686.1656 cm⁻¹ and 640.7251 cm⁻¹, respectively, and rotational and Coriolis constants.     

14.

A Combined Frequency Analysis of the ν_3, ν_9, 3ν₄ and the Far-Infrared Bands of Ethane: A Reassessment of the Torsional Parameters for the Ground Vibrational State     

N. Moazzen-Ahmadi 《Journal of Molecular Spectroscopy》2002,214(2):144-151

The lowest frequency parallel fundamental band ν₃ of ethane is Raman active. A stimulated Raman spectrum of the Q branch for this band at a resolution of 0.0055 cm⁻¹ has been measured by D. Bermejo et al. (1992, J. Chem. Phys.97, 7055). The torsion-rotation series in this band with σ=3, where σ=0, 1, 2, and 3 labels the torsional sublevels, is perturbed by over 1 cm⁻¹. The lowest frequency-degenerate fundamental ν₉ is infrared active. A high-resolution (0.0014 cm⁻¹) Fourier transform spectrum of this band has been measured by N. Moazzen-Ahmadi et al. (1999, J. Chem. Phys.111, 9609). The observed torsional splittings for this band are substantially larger than expected from the observed barrier height. Because of a near-degeneracy of the upper level in the ν₉ band with its interacting partner (v₉=0, v₄=3) a perturbation allowed band 3ν₄ has also been observed. We have carried out a combined analysis of ν₃, ν_9, and 3ν₄ together with the far-infrared torsional spectra in the ground vibrational state (gs). A fit to within the experimental error was achieved using 37 parameters. The large torsional splittings in the ν₉ band are attributed to Coriolis-type interactions between the torsional stacks of gs and v₉=1 whereas the large shift for the torsion-rotation series with σ=3 in the ν₃ band is attributed to Fermi-type interactions between the torsional stacks of the gs and v₃=1. The introduction of the Fermi-type interactions causes a considerable change in the leading terms in the torsional Hamiltonian for the gs. These changes are quantitatively explained.     

15.

High-Resolution Infrared Study of PHD₂: The P-H Stretching Bands ν₁ and 2ν₁     

O.N Ulenikov  O.L Petrunina  E.S Bekhtereva  E.A Sinitsin  H BürgerW Jerzembeck 《Journal of Molecular Spectroscopy》2002,215(1):85-92

For the first time the infrared spectrum of PHD₂ was recorded in the region of the PH stretching fundamental ν₁ at 2324.005 cm⁻¹ and the overtone 2ν₁ at 4563.634 cm⁻¹ with a resolution of 4.2×10⁻³ cm⁻¹ and 8.8×10⁻³ cm⁻¹, respectively. In the analyses about 1340 and 1020 transitions were assigned to the corresponding ν₁ and 2ν₁ bands, which provided 316 and 248 upper energies, respectively. Since both the bands are sufficiently isolated, a standard Watson-type Hamiltonian (A-reduction, I^r-representation) was employed. The obtained sets of spectroscopic parameters correlate very well both with each other, and with the corresponding parameters of the ground vibrational state.     

16.

Assignment, fit, and theoretical discussion of the ν₁₀ band of acetaldehyde near 509 cm     

I. Kleiner  N. Moazzen-Ahmadi  T.A. Blake  S.W. Sharpe  J.T. Hougen 《Journal of Molecular Spectroscopy》2008,252(2):214-229

The lowest small-amplitude vibration in acetaldehyde (CH₃CHO) is the in-plane aldehyde scissors mode ν₁₀ at 509 cm⁻¹. This mode lies about 175 cm⁻¹ above the top of the barrier to internal rotation of the methyl group and is relatively well separated from other small-amplitude vibrational states (the next fundamental occurring more than 250 cm⁻¹ higher). It thus provides an excellent example of an isolated small-amplitude fundamental (bright state) embedded in a bath of dark states. Since the bath states at these energies are not too dense, and since they arise purely from states of the large-amplitude torsional vibration of the methyl rotor, a detailed spectroscopic analysis of interactions between the bright state and the bath states should be possible. This paper represents the first step toward that goal. We have assigned several thousand transitions in the ν₁₀ band (J ? 28, K ? 12), and have carried out a simultaneous fit of 2400 of these transitions (J ? 15, K ? 9) with over 8100 transitions to the torsional bath state levels. Three vibration-torsion interactions, which give rise to rather global level shifts of the order of 1 cm⁻¹ in the ν₁₀ levels, have been identified and quantitatively fit. A number of vibration-torsion-rotation interactions, which give rise to localized (avoided-crossing) shifts in ν₁₀ have also been determined. The present analysis indicates the need for reliable spectroscopic information on more of the torsional bath states in the immediate vicinity of the ν₁₀ levels. Possible ways of obtaining such information in future studies are considered.     

17.

First High-Resolution Raman Spectrum and Analysis of the ν₅ Bending Fundamental of SF₆     

V. BoudonD. Bermejo 《Journal of Molecular Spectroscopy》2002,213(2):139-144

The high-resolution Raman spectrum of the Q, R, and S branches of the ν₅ bending fundamental of SF₆ has been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. This is the first study ever performed of a ν₅ band of an XY₆ molecule. It has been analyzed thanks to the HTDS software (http://www.u-bourgogne.fr/LPUB/shTDS.html) developed in Dijon. This contribution should be of help in understanding the role hot bands in the strong absorbing ν₃ region.     

18.

Vibration-Torsion-Rotation Study of the ν₅ State of CH₃CF₃     

S.-X. Wang  J. Schroderus  I. Ozier  N. Moazzen-AhmadiV.-M. Horneman  V.V. IlyushynE.A. Alekseev  A.A. KatrichS.F. Dyubko 《Journal of Molecular Spectroscopy》2002,214(1):69-79

An investigation of the torsion-rotation-vibration energies in the ν₅ vibrational state in CH₃CF₃ has been carried out using infrared and mm-wave spectroscopy. The lowest frequency parallel fundamental band ν₅ near 600 cm⁻¹ has been measured at a resolution of 0.00125 cm⁻¹ with Fourier transform spectroscopy for the two lowest torsional states v₆=0 and 1. The cold band (v₅=1, v₆=0)←(v₅=0, v₆=0) showed no torsional splittings and looked much like a parallel band in a C_3v molecule. The hot band (v₅=1, v₆=1)←(v₅=0, v₆=1) consisted of three distinct subbands, one for each torsional sublevel σ=0, +1, and −1. For the state (v₅=1, v₆=1), the torsional splitting was increased from ∼0.001 cm⁻¹ to ∼0.022 cm⁻¹ by torsion-mediated Fermi-type interaction primarily with the dark state (v₅=0, v₆=5). The effects of this coupling on the spectrum are striking in spite of the fact that the two interacting states are ∼100 cm⁻¹ apart and differ by four units in v₆. The large amplitude character of the state (v₅=0, v₆=5) is seen to be largely responsible for the unusual (k, σ) dependence of the energies in the state (v₅=1, v₆=1). The pure rotational spectrum in the state (v₅=1, v₆=0) has been measured between ∼50 and 370 GHz with Doppler-limited resolution; no σ-splitting was detected. The 3590 infrared and mm-wave frequencies measured here have been analyzed together with the 1494 measurements reported earlier by Wang et al. in an analysis of the vibrational ground state (2001, J. Mol. Spectrosc.205, 146-163). A good fit was obtained here by varying 36 parameters in a Hamiltonian which takes into account the interaction between the torsional stacks of levels for v₅=0 and 1, as well as the (A₁−A₂) splittings measured earlier for v₅=0. The explicit treatment of the interstack interactions is shown to lead to significant changes in the parameters (V_0,3, V_0,6) that characterize the torsional potential for v₅=0. These changes have been explained quantitatively by examining the contact transformation that is implicitly applied when the interstack coupling is neglected.     

19.

High-Resolution FTIR Spectra of CD₂Cl₂: Analysis of the ν₃/ν₇/ν₉ Triad     

Marcel Snels  Giuseppe D'AmicoEl Bachir Mkadmi 《Journal of Molecular Spectroscopy》2002,216(2):191-196

The infrared spectra of isotopically pure CD₂³⁵Cl₂ have been recorded at a resolution of 0.0026 cm⁻¹ (FWHM) in the range 600-1160 cm⁻¹ with a Bruker IFS 120 HR Fourier transform interferometer. The absorption between 670 and 750 cm⁻¹ is due to three fundamentals, ν₃ (weak), ν₇ (very weak), and ν₉ (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between ν₃ and ν₉ and a b-Coriolis term between ν₇ and ν₉. Although no transitions could be observed for the very weak ν₇ band, its band origin could be estimated from the Coriolis interaction with ν₉. From the analysis of about 4200 assigned transitions of the ν₃ and ν₉ bands, excited state constants have been determined up to sextic terms. The Coriolis parameters obtained are compared to those calculated from a harmonic force field.     

20.

A multispectrum analysis of the ν₄ band of CH₄: Widths, shifts, and line mixing coefficients     

M.A.H. Smith  D. Chris Benner  V. Malathy Devi 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(6):952-968

Line positions, Lorentz air-broadened half width and air pressure-induced shift coefficients have been measured for nearly 200 transitions in the ν₄ band of ¹³CH₄ from high-resolution spectra recorded with the McMath-Pierce Fourier transform spectrometer. Three room temperature spectra of ¹³CH₄ used in the previous study of Malathy Devi et al. (Air-broadened Lorentz halfwidths and pressure-induced line shifts in the ν₄ band of ¹³CH₄. Appl. Opt. 1988; 27: 2296-2308) were analyzed together with a large number of additional spectra of self- and air-broadened CH₄ recorded at 210-314 K and one room-temperature spectrum of self-broadened ¹³CH₄. Analyses applying the multispectrum nonlinear least squares fitting technique were performed to retrieve the spectral line parameters. In addition to air-broadened half width and shift coefficients, self-broadened half width and shift coefficients were determined for at least 56 ¹³CH₄ ν₄ transitions. Off-diagonal relaxation matrix element coefficients for air-broadened line mixing were also determined for 28 pairs of P and R transitions in a number of J manifolds, and mixing parameters for self-broadening were also determined for some of these pairs. Temperature-dependences of the pressure-induced shift and mixing parameters for the ¹³CH₄ lines could not be determined from the spectra used in the present analysis, but temperature dependences of the half width coefficients were determined for the strongest transitions. The results of this study are compared with other studies of air- and self-broadened ¹³CH₄ and ¹²CH₄.     

Band	$\text{ν}{}_0$	$\text{A-}\text{B}$	B	C
$\text{ν}{}_1$	3533.1	27.0	—	—
$\text{3ν}{}_1$	10145.79	22.6713	0.368426	0.361722

The (ν1, ν4, ν2+ν3, ν3+ν5) Polyad of D3SiF around 1600 cm, Studied by High-Resolution FTIR Spectroscopy

The ν₁ (A₁, 1578.31 cm⁻¹)/ν₄(E, 1615.17 cm⁻¹) Si-D stretching dyad of D₃SiF has been studied by FTIR spectroscopy with a resolution of 2.4×10⁻³ cm⁻¹. Only weak interactions of Coriolis (ΔK=±1, Δ?=±1) and α resonance (ΔK=±2, Δ?=?1) type between ν₁ and ν₄, and of ? (2,−4) type within ν₄, were revealed. However, the v₁=1 and v₄=1 levels were found to be severely perturbed by the v₃=v₅=1 (E, 1590.37 cm⁻¹) and v₂=v₃=1 (A₁, 1604.25 cm⁻¹) states. These perturbations are observable only near level crossings involving strong Coriolis and α interactions. The energy structure within these perturbers is severely complicated by strong Coriolis and α resonances and by ? (2, 2), ? (2,−1), and ? (2,−4) interactions as already revealed by the ν₂(A₁, 710.16 cm⁻¹) and ν₅ (E, 701.72 cm⁻¹) fundamentals. Interactions of the perturbing states with the ν₁/ν₄ dyad are particularly evident in local crossings. In total, 12 transitions belonging to the dark states and 68 perturbation-allowed transitions within the ν₁/ν₄ dyad have been detected among the more than 5000 transitions that have been assigned for the ν₁/ν₄ dyad, with J_max and K_max of 50 and 30, respectively. Altogether about 85% of the assigned transitions were fitted with a standard deviation of 0.221×10⁻³ cm⁻¹, leading to 61 parameters of the interacting polyad.     

The ν1, ν2, and ν3 bands of carbonyl chlorofluoride (COFCl) at 5.3, 9.1, and 13.1 μm: position and intensity parameters and their use for atmospheric studies

A list of line positions and, for the first time, of line intensities was generated for the ν₁, ν₂, and ν₃ fundamental bands of the ¹²C¹⁶OF³⁵Cl and ¹²C¹⁶OF³⁷Cl isotopologs of carbonyl chlorofluoride, located at 5.3, 9.1, and 13.1 μm, respectively. In addition, for the most abundant isotopolog (¹²C¹⁶OF³⁵Cl) this linelist includes also the contributions from the first two associated hot bands. The parameters included in this database were generated by combining the results of previous experimental analyses and ab initio calculations [Perrin A, Flaud JM, Bürger H, Pawelke G, Sander S, Willner H. First high resolution analysis of the six fundamental bands ν₁, ν₂, ν₃, ν₄, ν₅ and ν₆ of COF³⁵Cl in the 340 to 2000 cm⁻¹ region. J Mol Spectrosc 2001;209:122-232; Demaison J, Perrin A, Bürger H. Ab initio anharmonic force field and equilibrium structure of carbonyl chlorofluoride. J Mol Spectrosc 2003;221:47-56]. For the purpose of the present work, a partial re-investigation of the ν₁ of COF³⁵Cl was performed, together with the first identification of the ν₂ band of COF³⁷Cl.These parameters were generated in order to improve the quality of remote sensing of the atmosphere in the mid-IR. Analyses of atmospheric solar occultation spectra measured by the JPL MkIV interferometer show that the new linelist not only improves the quality of retrievals of COFCl, but also of several other gases whose absorptions overlap those of COFCl.     

Search for νμ and ντ supernova neutrinos with massive liquid-scintillation detectors

Summary In this paper we have estimated the sensitivity of a large-mass liquid-scintillation detector to search for supernova neutrinos of different flavours. Events produced by ν_μ and ν_τ interactions can be identified by looking at the distorsion in the neutrino energy spectrum. We have shown here that, overlapped to the main energy distribution produced by interactions with protons a peak at 15.11 MeV (due to the de-excitation of¹²C^* nuclei excited by neutral-current neutrino interactions) gives a possible signature of these neutrino flavours. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

First Gas Phase Infrared Spectroscopy of F2BOH: High-Resolution Study of the ν8 and ν9 Bands

For the first time the infrared spectrum of F₂BOH in the gas phase has been observed. After optimizing the conditions for the synthesis we have been able to obtain high-resolution (2.4-3.3×10⁻³ cm⁻¹) infrared spectra in the ν₈, ν₉, and ν₄ regions with both natural and ¹¹B monoisotopic material. Analyses of the ν₈ (BF₂ out-of-plane bending) and ν₉ (OH torsion) fundamental bands located at 684.160 and 522.870 cm⁻¹, respectively, for F₂¹¹BOH are presented here. Existing J≤10 microwave transitions were combined with novel ground state combination differences with J≤55 formed from A-type (ν₄) and C-type (ν₈, ν₉) bands to yield substantially improved and extended ground state parameters. Using a standard Watson-type Hamiltonian, 8¹ and 9¹ upper state parameters were obtained by fitting about 2000 lines each with σ(fit) ca. 3.5×10⁻⁴ cm⁻¹. The 8¹ and 9¹ states both appear to be unperturbed, as indicated by the agreement of the ground and excited state centrifugal distortion constants.     

Water Spectra in the Region 4200-6250 cm, Extended Analysis of ν1+ν2, ν2+ν3, and 3ν2 Bands and Confirmation of Highly Excited States from Flame Spectra and from Atmospheric Long-Path Observations

Water vapor infrared spectra have been recorded at room temperature in the range 4200-6250 cm⁻¹ at resolutions (FWHM) between 0.0053 and 0.0080 cm⁻¹. The use of a White-type multireflection cell made large pressure × pathlength products possible up to 31.27 mbar×288.5 m. The high signal-to-noise ratio allowed us to observe lines with intensities as small as 10⁻²⁶ cm⁻¹/molecule cm⁻² at T=296 K. Among about 5100 recorded water lines, about half of which are reported for the first time, 2351 lines have been assigned to the second triad of H₂¹⁶O (bands ν₁+ν₂, ν₂+ν₃, and 3ν₂). This has allowed the determination of line positions and corresponding upper rovibrational states with considerably improved accuracy. The assignments of certain highly excited states have been confirmed by the analysis of flame spectra and hot emission spectra. New values of effective Hamiltonian parameters for the upper states {(110), (030), (011)} have been determined. The generating function model was used in the data reduction to account for the anomalously strong centrifugal distortion of the rovibrational levels and resonance interactions. The RMS standard deviation of the least-squares fit of the assigned H₂O data was 5×10⁻³ cm⁻¹ for line positions and 7×10⁻³ cm⁻¹ for energy levels up to J_max=20 and K_a(max)=13. Particular attention was paid to water lines in the transparency window 4200-5000 cm⁻¹, in which existing databases are not sufficient. In this region, 1395 lines of four isotopic species of water have been recorded and over 900 accurate line positions of nine bands of H₂¹⁶O (ν₁, ν₃, 2ν₂, ν₁+ν₂, ν₂+ν₃, 3ν₂, 4ν₂−ν₂, 2ν₂+ν₃−ν₂, ν₁+2ν₂−ν₂) are reported in this range. A comparison of laboratory spectra with long path atmospheric spectra (20 km slant path in the mountains) in this region shows that many lines missing from available spectroscopic compilations (or considerably shifted compared to observations) are important for a proper interpretation of atmospheric observations. A comparison of the observed data with the best available predictions from the molecular electronic potential energy surface is discussed.     

New High-Resolution Analysis of the ν7 and ν9 Fundamental Bands of trans-Formic Acid by Fourier Transform Infrared and Millimeter-Wave Spectroscopy

The high-resolution (0.002 cm⁻¹) spectrum of the ν₇ (OCO scissor mode) and ν₉ (COH torsion mode) fundamental bands of trans-formic acid (HCOOH) at 15.8 μm was recorded by Fourier transform infrared spectroscopy. In addition, millimeter-wave transitions within the 7¹ and 9¹ vibrational states were measured in the spectral range 340-600 GHz. Using these new experimental data, an extensive analysis of the ν₇ and ν₉ bands was performed. The model we have used accounts for the strong A- and B-type Coriolis interactions which couple the 7¹ and 9¹ vibrational states and which were already pointed out in the literature [J. C. Deroche, J. Kauppinen and E. Kyrö, J. Mol. Spectrosc.78, 379-394 (1979); E. Willemot, J. Mol. Spectrosc.120, 246-275 (1986)]. The observed levels are fit to within the experimental accuracy leading to the determination of a precise set of band centers of ν₇ and ν₉ at 686.1656 cm⁻¹ and 640.7251 cm⁻¹, respectively, and rotational and Coriolis constants.     

A Combined Frequency Analysis of the ν3, ν9, 3ν4 and the Far-Infrared Bands of Ethane: A Reassessment of the Torsional Parameters for the Ground Vibrational State

The lowest frequency parallel fundamental band ν₃ of ethane is Raman active. A stimulated Raman spectrum of the Q branch for this band at a resolution of 0.0055 cm⁻¹ has been measured by D. Bermejo et al. (1992, J. Chem. Phys.97, 7055). The torsion-rotation series in this band with σ=3, where σ=0, 1, 2, and 3 labels the torsional sublevels, is perturbed by over 1 cm⁻¹. The lowest frequency-degenerate fundamental ν₉ is infrared active. A high-resolution (0.0014 cm⁻¹) Fourier transform spectrum of this band has been measured by N. Moazzen-Ahmadi et al. (1999, J. Chem. Phys.111, 9609). The observed torsional splittings for this band are substantially larger than expected from the observed barrier height. Because of a near-degeneracy of the upper level in the ν₉ band with its interacting partner (v₉=0, v₄=3) a perturbation allowed band 3ν₄ has also been observed. We have carried out a combined analysis of ν₃, ν_9, and 3ν₄ together with the far-infrared torsional spectra in the ground vibrational state (gs). A fit to within the experimental error was achieved using 37 parameters. The large torsional splittings in the ν₉ band are attributed to Coriolis-type interactions between the torsional stacks of gs and v₉=1 whereas the large shift for the torsion-rotation series with σ=3 in the ν₃ band is attributed to Fermi-type interactions between the torsional stacks of the gs and v₃=1. The introduction of the Fermi-type interactions causes a considerable change in the leading terms in the torsional Hamiltonian for the gs. These changes are quantitatively explained.     

High-Resolution Infrared Study of PHD2: The P-H Stretching Bands ν1 and 2ν1

For the first time the infrared spectrum of PHD₂ was recorded in the region of the PH stretching fundamental ν₁ at 2324.005 cm⁻¹ and the overtone 2ν₁ at 4563.634 cm⁻¹ with a resolution of 4.2×10⁻³ cm⁻¹ and 8.8×10⁻³ cm⁻¹, respectively. In the analyses about 1340 and 1020 transitions were assigned to the corresponding ν₁ and 2ν₁ bands, which provided 316 and 248 upper energies, respectively. Since both the bands are sufficiently isolated, a standard Watson-type Hamiltonian (A-reduction, I^r-representation) was employed. The obtained sets of spectroscopic parameters correlate very well both with each other, and with the corresponding parameters of the ground vibrational state.     

Assignment, fit, and theoretical discussion of the ν10 band of acetaldehyde near 509 cm

The lowest small-amplitude vibration in acetaldehyde (CH₃CHO) is the in-plane aldehyde scissors mode ν₁₀ at 509 cm⁻¹. This mode lies about 175 cm⁻¹ above the top of the barrier to internal rotation of the methyl group and is relatively well separated from other small-amplitude vibrational states (the next fundamental occurring more than 250 cm⁻¹ higher). It thus provides an excellent example of an isolated small-amplitude fundamental (bright state) embedded in a bath of dark states. Since the bath states at these energies are not too dense, and since they arise purely from states of the large-amplitude torsional vibration of the methyl rotor, a detailed spectroscopic analysis of interactions between the bright state and the bath states should be possible. This paper represents the first step toward that goal. We have assigned several thousand transitions in the ν₁₀ band (J ? 28, K ? 12), and have carried out a simultaneous fit of 2400 of these transitions (J ? 15, K ? 9) with over 8100 transitions to the torsional bath state levels. Three vibration-torsion interactions, which give rise to rather global level shifts of the order of 1 cm⁻¹ in the ν₁₀ levels, have been identified and quantitatively fit. A number of vibration-torsion-rotation interactions, which give rise to localized (avoided-crossing) shifts in ν₁₀ have also been determined. The present analysis indicates the need for reliable spectroscopic information on more of the torsional bath states in the immediate vicinity of the ν₁₀ levels. Possible ways of obtaining such information in future studies are considered.     

First High-Resolution Raman Spectrum and Analysis of the ν5 Bending Fundamental of SF6

The high-resolution Raman spectrum of the Q, R, and S branches of the ν₅ bending fundamental of SF₆ has been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. This is the first study ever performed of a ν₅ band of an XY₆ molecule. It has been analyzed thanks to the HTDS software (http://www.u-bourgogne.fr/LPUB/shTDS.html) developed in Dijon. This contribution should be of help in understanding the role hot bands in the strong absorbing ν₃ region.     

Vibration-Torsion-Rotation Study of the ν5 State of CH3CF3

An investigation of the torsion-rotation-vibration energies in the ν₅ vibrational state in CH₃CF₃ has been carried out using infrared and mm-wave spectroscopy. The lowest frequency parallel fundamental band ν₅ near 600 cm⁻¹ has been measured at a resolution of 0.00125 cm⁻¹ with Fourier transform spectroscopy for the two lowest torsional states v₆=0 and 1. The cold band (v₅=1, v₆=0)←(v₅=0, v₆=0) showed no torsional splittings and looked much like a parallel band in a C_3v molecule. The hot band (v₅=1, v₆=1)←(v₅=0, v₆=1) consisted of three distinct subbands, one for each torsional sublevel σ=0, +1, and −1. For the state (v₅=1, v₆=1), the torsional splitting was increased from ∼0.001 cm⁻¹ to ∼0.022 cm⁻¹ by torsion-mediated Fermi-type interaction primarily with the dark state (v₅=0, v₆=5). The effects of this coupling on the spectrum are striking in spite of the fact that the two interacting states are ∼100 cm⁻¹ apart and differ by four units in v₆. The large amplitude character of the state (v₅=0, v₆=5) is seen to be largely responsible for the unusual (k, σ) dependence of the energies in the state (v₅=1, v₆=1). The pure rotational spectrum in the state (v₅=1, v₆=0) has been measured between ∼50 and 370 GHz with Doppler-limited resolution; no σ-splitting was detected. The 3590 infrared and mm-wave frequencies measured here have been analyzed together with the 1494 measurements reported earlier by Wang et al. in an analysis of the vibrational ground state (2001, J. Mol. Spectrosc.205, 146-163). A good fit was obtained here by varying 36 parameters in a Hamiltonian which takes into account the interaction between the torsional stacks of levels for v₅=0 and 1, as well as the (A₁−A₂) splittings measured earlier for v₅=0. The explicit treatment of the interstack interactions is shown to lead to significant changes in the parameters (V_0,3, V_0,6) that characterize the torsional potential for v₅=0. These changes have been explained quantitatively by examining the contact transformation that is implicitly applied when the interstack coupling is neglected.     

High-Resolution FTIR Spectra of CD2Cl2: Analysis of the ν3/ν7/ν9 Triad

The infrared spectra of isotopically pure CD₂³⁵Cl₂ have been recorded at a resolution of 0.0026 cm⁻¹ (FWHM) in the range 600-1160 cm⁻¹ with a Bruker IFS 120 HR Fourier transform interferometer. The absorption between 670 and 750 cm⁻¹ is due to three fundamentals, ν₃ (weak), ν₇ (very weak), and ν₉ (strong). A satisfactory analysis of the observed spectra has been obtained by including a c-Coriolis coupling between ν₃ and ν₉ and a b-Coriolis term between ν₇ and ν₉. Although no transitions could be observed for the very weak ν₇ band, its band origin could be estimated from the Coriolis interaction with ν₉. From the analysis of about 4200 assigned transitions of the ν₃ and ν₉ bands, excited state constants have been determined up to sextic terms. The Coriolis parameters obtained are compared to those calculated from a harmonic force field.     

A multispectrum analysis of the ν4 band of CH4: Widths, shifts, and line mixing coefficients

Line positions, Lorentz air-broadened half width and air pressure-induced shift coefficients have been measured for nearly 200 transitions in the ν₄ band of ¹³CH₄ from high-resolution spectra recorded with the McMath-Pierce Fourier transform spectrometer. Three room temperature spectra of ¹³CH₄ used in the previous study of Malathy Devi et al. (Air-broadened Lorentz halfwidths and pressure-induced line shifts in the ν₄ band of ¹³CH₄. Appl. Opt. 1988; 27: 2296-2308) were analyzed together with a large number of additional spectra of self- and air-broadened CH₄ recorded at 210-314 K and one room-temperature spectrum of self-broadened ¹³CH₄. Analyses applying the multispectrum nonlinear least squares fitting technique were performed to retrieve the spectral line parameters. In addition to air-broadened half width and shift coefficients, self-broadened half width and shift coefficients were determined for at least 56 ¹³CH₄ ν₄ transitions. Off-diagonal relaxation matrix element coefficients for air-broadened line mixing were also determined for 28 pairs of P and R transitions in a number of J manifolds, and mixing parameters for self-broadening were also determined for some of these pairs. Temperature-dependences of the pressure-induced shift and mixing parameters for the ¹³CH₄ lines could not be determined from the spectra used in the present analysis, but temperature dependences of the half width coefficients were determined for the strongest transitions. The results of this study are compared with other studies of air- and self-broadened ¹³CH₄ and ¹²CH₄.