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.     

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.     

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.     

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.     

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):

     

6.

Rotational analysis of 6ν₃ and 6ν₃+ν₂−ν₂ bands of N₂O from ICLAS spectra between 12,760 and 12,900 cm     

R. Milloud  S.A. Tashkun 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(3):553-557

The absorption spectrum of nitrous oxide (N₂O) has been recorded by Intracavity Laser Absorption Spectroscopy between 12,760 and 12,900 cm⁻¹. The rotational analysis led to an improved determination of rovibrational parameters of the 6ν₃ and 6ν₃+ν₂-ν₂ bands of ¹⁴N₂¹⁶O. The high J rotational levels of the (0 0 ⁰6) and (0 1 ¹6) upper states were found perturbed by an anharmonic interaction. Line intensity values of the 6ν₃ band are provided and the main effective dipole moment parameter has been determined.     

7.

HIGH-RESOLUTION ANALYSIS OF THE ν₂+2ν₃ BAND OF HDO          下载免费PDF全文

胡水明  何圣贵  郑晶晶  王湘淮  丁昀  朱清时 《中国物理》2001,10(11):1021-1027

The Fourier transform spectrum of the ν₂+2ν₃ band of the HDO molecule was recorded with a resolution of 0.02 cm^-1. The spectrum was rotational analysed and the spectroscopic parameters of the (0,1,2) state were estimated in terms of Watson's effective rotational Hamiltonian model and also the model in the Padé-Borel approximation form. They reproduce the upper energy levels with an accuracy close to the experimental uncertainty of 0.001 cm^-1.     

8.

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

L.H. CoudertP. Çarçabal  M. ChevalierM. Broquier  M. HeppM. Herman 《Journal of Molecular Spectroscopy》2002,212(2):203-207

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.     

9.

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

F. WintherM. Schönhoff  A. Huckauf  E.B. Mkadmi 《Journal of Molecular Spectroscopy》2002,216(2):374-378

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.     

10.

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

R.Wugt LarsenF. Hegelund  J. CeponkusB. Nelander 《Journal of Molecular Spectroscopy》2002,211(1):127-134

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.     

11.

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

Jeffrey BarberEngelene t.H. Chrysostom  Tony MasielloJoseph W. Nibler  Arthur MakiAlfons Weber  Thomas A. BlakeRobert L. Sams 《Journal of Molecular Spectroscopy》2002,216(1):105-112

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.     

12.

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.     

13.

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.     

14.

Line intensities of the: ν₃, 4ν₂, ν₁+ν₃, 3ν₁ and 2ν₁+2ν₂ bands of OCS molecule     

L. Régalia-Jarlot  A. HamdouniX. Thomas  P. Von der HeydenA. Barbe 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(4):455-470

     

15.

FTIR Study of the ν₁/ν₄ Bands of D₃SiCl near 1600 cm     

K. AkkadN.Ben Sari-Zizi  H. BürgerE.B. MKadmi 《Journal of Molecular Spectroscopy》2002,213(1):35-45

The ν₁ (A₁, 1583.22 cm⁻¹) and ν₄ (E, 1615.33 cm⁻¹) Si-D stretching bands of monoisotopic D₃Si³⁵Cl have been studied by FTIR spectroscopy with a resolution of 3.3×10⁻³ cm⁻¹. We have assigned 2341 rovibrational lines for ν₁ (J_max=70, K_max=19) and 6207 for ν₄ (J_max=75, K_max=27). Both (ΔK=±1, Δ?=±1) and (ΔK=±2, Δ?=?1) interactions connect the v₁=1 and v₄=1 levels, the latter exerting moreover a weak ?(2, 2) interaction. These interactions were taken into account in a nonlinear least-squares fit, refining 29 free parameters with a standard deviation of 0.257×10⁻³ cm⁻¹ over 6722 nonzero-weighted data. Blended lines and about 250 of the 330 lines belonging to the K=11 subband of ν₁ and the KΔK=−6 subband of ν₄ were zero-weighted because they are locally perturbed respectively by the neighboring upper states of the 2ν₃+ν₆ (E, 1561.95 cm⁻¹) and 3ν₃ (A₁, 1604.81 cm⁻¹) bands. Equivalent fits were obtained for altogether three different models obeying constraints according to the theory of unitary equivalent reductions of the rovibrational Hamiltonian. By means of a band contour simulation both the transition moment ratio |M₁:M₄|=0.67 and a positive sign of the Coriolis intensity perturbation were determined.     

16.

Temperature Variations of the Interaction Induced Absorption of CO₂ in the ν₁, 2ν₂ Region: FTIR Measurements and Dimer Contribution     

A.A. Vigasin  Y.I. BaranovG.V. Chlenova 《Journal of Molecular Spectroscopy》2002,213(1):51-56

The temperature variations in collision-induced absorption (CIA) spectra of carbon dioxide in the region of the Fermi doublet are examined. New FTIR CIA spectra are recorded in the temperature range T=206-296 K. The spectra were subject to decomposition in order to separate true dimer contributions to the CIA profile from the base absorption caused by unbound pairs. The use of statistical physics theory allowed for quite nice reproduction of the observed temperature variations of the normalized dimer intensity.     

17.

The Millimeter-Wave Spectrum of Chlorine Nitrate (ClONO₂): The 2ν₉ and ν₇ Vibrational States     

Rebecca A.H. ButlerSieghard Albert  Douglas T. PetkiePaul Helminger  Frank C. De Lucia 《Journal of Molecular Spectroscopy》2002,213(1):8-14

Chlorine nitrate is a molecule of interest in atmospheric studies because of its role as a reservoir species, removing both chlorine and nitrogen species from catalytic cycles of ozone destruction. The ground and ν₉ vibrational states have been previously studied in the millimeter and submillimeter spectral regions. We have now recorded and analyzed the next states that are lowest in energy, the coupled 2ν₉/ν₇ dyad, from 128 through 355 GHz using a fast scan submillimeter spectroscopic technique system.     

18.

The 2ν₁, 2ν₂ and 2ν₃ overtones of FClO₃     

E. Cané  G. Pawelke 《Journal of Molecular Spectroscopy》2007,244(1):24-32

The infrared spectra of the 2ν₁, 2ν₂ and 2ν₃ overtones of perchloryl fluoride, FClO₃, have been recorded at high resolution using monoisotopic pure samples. Four symmetric top species have been investigated: F³⁵Cl¹⁶O₃, F³⁷Cl¹⁶O₃, F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃. The v_i = 2, i = 1, 2, 3 vibrationally excited states are totally symmetric, so these overtones correspond to parallel bands of medium/weak intensity, centered from 2010 to 2120 cm⁻¹ (2ν₁), from 1390 to 1430 cm⁻¹ (2ν₂) and from 1070 to 1100 cm⁻¹ (2ν₃). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v₁ = 2, v₂ = 2 and v₃ = 2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067 cm⁻¹. The 2ν₁ overtones of F³⁵Cl¹⁶O₃ and F³⁷Cl¹⁶O₃ are perturbed by an A₁/E Coriolis resonance between the v₁ = 2 state and one E component of the v₄ = 1, v₆ = 2 manifold. The 2ν₂ of F³⁷Cl¹⁸O₃ is perturbed by the same kind of interaction involving the v₁ = v₆ = 1 (E) state, at about 1396 cm⁻¹. In these bands the resonance is localized on rotational levels with specific J and K values. As a consequence, a few transitions of the perpendicular bands involving the interacting levels could be identified in the spectra. A simultaneous fit of the transitions assigned to the dyads has been performed and the parameters of the excited states have been determined, including the high order Coriolis interaction coefficient . The anharmonic constants x₁₁, x₂₂, x₃₃ of all the studied isotopologues of FClO₃, x₄₆ of F³⁵Cl¹⁶O₃, x₄₆ + g₄₆ of F³⁷Cl¹⁶O₃ and x₁₆ of F³⁷Cl¹⁸O₃, have been derived.     

19.

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule     

Zhabina  E. A.  Onopenko  G. A.  Ulenikov  O. N.  Burger  G.  Jerzembeck  W. 《Russian Physics Journal》2002,45(5):483-487

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

20.

Simultaneous analysis of the 2ν₂, 2ν₅, and ν₂ + ν₅ vibration-rotation bands of CH₃Br     

C Betrencourt-Stirnemann  G Graner  D.E Jennings  W.E Blass 《Journal of Molecular Spectroscopy》1978,69(2):179-198

Previous studies of the parallel bands 2ν₂ and $\text{2ν}{}_5{}^0$ of CH₃Br by the two first authors have been completed by the analysis of the weaker perpendicular band ν₂ + ν₅, centered near 2745 cm^?1. It is well known that the v₂ = 1 and v₅ = 1 states of methylbromide are linked by an x-y-type Coriolis interaction. Therefore, in the 2500–2900-cm^?1 range, the levels

$\text{(v}{}_2\text{=2), (v}{}_5\text{2, l}{}_5\text{=0), (v}{}_5\text{=2, l}{}_5\text{±2), (v}{}_5\text{=v}{}_2\text{=1, l=5±1)}$

are linked by a similar interaction. Least-squares and prediction programs have been written to treat this kind of problems and they have been satisfactorily applied to both isotopic species, CH₃⁷⁹Br and CH₃⁸¹Br. A localized resonance in the K = 0 subband of ν₂ + ν₅ has been shown to be due to the 3ν₃ + ν₆ band. No evidence for a strong Fermi resonance between ν₁ and $\text{2ν}{}_5{}^0$ has been found.     

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

Rotational analysis of 6ν3 and 6ν3+ν2−ν2 bands of N2O from ICLAS spectra between 12,760 and 12,900 cm

The absorption spectrum of nitrous oxide (N₂O) has been recorded by Intracavity Laser Absorption Spectroscopy between 12,760 and 12,900 cm⁻¹. The rotational analysis led to an improved determination of rovibrational parameters of the 6ν₃ and 6ν₃+ν₂-ν₂ bands of ¹⁴N₂¹⁶O. The high J rotational levels of the (0 0 ⁰6) and (0 1 ¹6) upper states were found perturbed by an anharmonic interaction. Line intensity values of the 6ν₃ band are provided and the main effective dipole moment parameter has been determined.     

HIGH-RESOLUTION ANALYSIS OF THE ν2+2ν3 BAND OF HDO

The Fourier transform spectrum of the ν₂+2ν₃ band of the HDO molecule was recorded with a resolution of 0.02 cm^-1. The spectrum was rotational analysed and the spectroscopic parameters of the (0,1,2) state were estimated in terms of Watson's effective rotational Hamiltonian model and also the model in the Padé-Borel approximation form. They reproduce the upper energy levels with an accuracy close to the experimental uncertainty of 0.001 cm^-1.     

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.     

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.     

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.     

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.     

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.     

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.     

FTIR Study of the ν1/ν4 Bands of D3SiCl near 1600 cm

The ν₁ (A₁, 1583.22 cm⁻¹) and ν₄ (E, 1615.33 cm⁻¹) Si-D stretching bands of monoisotopic D₃Si³⁵Cl have been studied by FTIR spectroscopy with a resolution of 3.3×10⁻³ cm⁻¹. We have assigned 2341 rovibrational lines for ν₁ (J_max=70, K_max=19) and 6207 for ν₄ (J_max=75, K_max=27). Both (ΔK=±1, Δ?=±1) and (ΔK=±2, Δ?=?1) interactions connect the v₁=1 and v₄=1 levels, the latter exerting moreover a weak ?(2, 2) interaction. These interactions were taken into account in a nonlinear least-squares fit, refining 29 free parameters with a standard deviation of 0.257×10⁻³ cm⁻¹ over 6722 nonzero-weighted data. Blended lines and about 250 of the 330 lines belonging to the K=11 subband of ν₁ and the KΔK=−6 subband of ν₄ were zero-weighted because they are locally perturbed respectively by the neighboring upper states of the 2ν₃+ν₆ (E, 1561.95 cm⁻¹) and 3ν₃ (A₁, 1604.81 cm⁻¹) bands. Equivalent fits were obtained for altogether three different models obeying constraints according to the theory of unitary equivalent reductions of the rovibrational Hamiltonian. By means of a band contour simulation both the transition moment ratio |M₁:M₄|=0.67 and a positive sign of the Coriolis intensity perturbation were determined.     

Temperature Variations of the Interaction Induced Absorption of CO2 in the ν1, 2ν2 Region: FTIR Measurements and Dimer Contribution

The temperature variations in collision-induced absorption (CIA) spectra of carbon dioxide in the region of the Fermi doublet are examined. New FTIR CIA spectra are recorded in the temperature range T=206-296 K. The spectra were subject to decomposition in order to separate true dimer contributions to the CIA profile from the base absorption caused by unbound pairs. The use of statistical physics theory allowed for quite nice reproduction of the observed temperature variations of the normalized dimer intensity.     

The Millimeter-Wave Spectrum of Chlorine Nitrate (ClONO2): The 2ν9 and ν7 Vibrational States

Chlorine nitrate is a molecule of interest in atmospheric studies because of its role as a reservoir species, removing both chlorine and nitrogen species from catalytic cycles of ozone destruction. The ground and ν₉ vibrational states have been previously studied in the millimeter and submillimeter spectral regions. We have now recorded and analyzed the next states that are lowest in energy, the coupled 2ν₉/ν₇ dyad, from 128 through 355 GHz using a fast scan submillimeter spectroscopic technique system.     

The 2ν1, 2ν2 and 2ν3 overtones of FClO3

The infrared spectra of the 2ν₁, 2ν₂ and 2ν₃ overtones of perchloryl fluoride, FClO₃, have been recorded at high resolution using monoisotopic pure samples. Four symmetric top species have been investigated: F³⁵Cl¹⁶O₃, F³⁷Cl¹⁶O₃, F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃. The v_i = 2, i = 1, 2, 3 vibrationally excited states are totally symmetric, so these overtones correspond to parallel bands of medium/weak intensity, centered from 2010 to 2120 cm⁻¹ (2ν₁), from 1390 to 1430 cm⁻¹ (2ν₂) and from 1070 to 1100 cm⁻¹ (2ν₃). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v₁ = 2, v₂ = 2 and v₃ = 2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067 cm⁻¹. The 2ν₁ overtones of F³⁵Cl¹⁶O₃ and F³⁷Cl¹⁶O₃ are perturbed by an A₁/E Coriolis resonance between the v₁ = 2 state and one E component of the v₄ = 1, v₆ = 2 manifold. The 2ν₂ of F³⁷Cl¹⁸O₃ is perturbed by the same kind of interaction involving the v₁ = v₆ = 1 (E) state, at about 1396 cm⁻¹. In these bands the resonance is localized on rotational levels with specific J and K values. As a consequence, a few transitions of the perpendicular bands involving the interacting levels could be identified in the spectra. A simultaneous fit of the transitions assigned to the dyads has been performed and the parameters of the excited states have been determined, including the high order Coriolis interaction coefficient . The anharmonic constants x₁₁, x₂₂, x₃₃ of all the studied isotopologues of FClO₃, x₄₆ of F³⁵Cl¹⁶O₃, x₄₆ + g₄₆ of F³⁷Cl¹⁶O₃ and x₁₆ of F³⁷Cl¹⁸O₃, have been derived.     

Analysis of the Vibrational-Rotational Structure of 2ν1, ν1 + ν3, and 2ν3 Bands of the D2Se Molecule

The absorption spectrum of the D₂Se molecule in the region of 2₁, ₁ + ₃, and 2₃ absorption bands is registered with a high-resolution Fourier spectrometer and is studied theoretically for a Hamiltonian model with allowance for resonant interactions among (200), (101), and (002) vibrational states.     

Simultaneous analysis of the 2ν2, 2ν5, and ν2 + ν5 vibration-rotation bands of CH3Br

Previous studies of the parallel bands 2ν₂ and $\text{2ν}{}_5{}^0$ of CH₃Br by the two first authors have been completed by the analysis of the weaker perpendicular band ν₂ + ν₅, centered near 2745 cm^?1. It is well known that the v₂ = 1 and v₅ = 1 states of methylbromide are linked by an x-y-type Coriolis interaction. Therefore, in the 2500–2900-cm^?1 range, the levels

$\text{(v}{}_2\text{=2), (v}{}_5\text{2, l}{}_5\text{=0), (v}{}_5\text{=2, l}{}_5\text{±2), (v}{}_5\text{=v}{}_2\text{=1, l=5±1)}$

are linked by a similar interaction. Least-squares and prediction programs have been written to treat this kind of problems and they have been satisfactorily applied to both isotopic species, CH₃⁷⁹Br and CH₃⁸¹Br. A localized resonance in the K = 0 subband of ν₂ + ν₅ has been shown to be due to the 3ν₃ + ν₆ band. No evidence for a strong Fermi resonance between ν₁ and $\text{2ν}{}_5{}^0$ has been found.