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The infrared spectrum of a sample containing13C mono-substituted isotopologues of acetylene, H12C13CH, H12C13CD, D12C13CH and D12C13CD has been recorded in the 6130−6800 cm− 1region using a femto-Fourier transform-cavity enhanced absorption spectroscopy (femto-FT-CEAS) apparatus. Three bands for both H12C13CD and D12C13CH were observed and analysed, namely 2ν1− GS and associated hot bands from ν4and ν5. The assignment of the 2ν1overtone already reported in the literature [J.L. Hardwick, Z.T. Martin, M.J. Pilkenton, E.N. Wolf, J. Mol. Spectrosc.243, 10 (2007)] was considerably extended to higherJvalues. For the D12C13CD isotopologue, four bands were analysed, ν1+ ν2+ ν3− GS and associated hot bands fromν4andν5and 2ν1+ ν4+ ν5− GS. [ABSTRACT FROM AUTHOR]

Context. Diacetylene, C4H2, has been identified in several astronomical environments through its infrared spectrum. In contrast, monodeuterated diacetylene (DC4H) has not been detected in space so far owing to the low isotopic abundance of deuterated species but also to the rather poor laboratory spectroscopic characterisation of this molecule. Aims. The aim of this work is to provide accurate spectroscopic parameters for DC4H to achieve reliable predictions for both its spectra at millimetre and infrared wavelengths. Methods. We studied the rotational spectrum of DC4H in the range 85-615 GHz by millimetre-wave spectroscopy and the infrared spectrum below 1000 cm-1 by high-resolution, Fourier-transform spectroscopy. Several pure rotational transitions were recorded in the ground state and in excited vibrational bending states. The three fundamental bands v6, v7, and v8 have been identified and assigned in the infrared spectrum. Results. The rotational transitions were analysed together with the infrared data in a global fit that produces very accurate rovibrational parameters. The observed frequencies and wavenumbers are reported to provide precise guidance for astronomical searches. [ABSTRACT FROM AUTHOR]

Abstract: The 2ν1 (A1) Si−H stretching overtone band of HSiD3 has been recorded at a resolution of ca. 0.009cm−1 between 4200 and 4400cm−1. About 790 ro-vibration transitions of the H28SiD3 isotopologue have been assigned, with J′ up to 24 and K up to 21. The spectrum evidences the existence of several perturbations. The assigned transitions have been analyzed either neglecting or including in the model A1/E Coriolis-type interactions between v 1 =2 and nearby dark states. The standard deviation of all the fits is, however, more than one order of magnitude larger than the estimated experimental precision and is independent of the adopted model. [Copyright &y& Elsevier]

Infrared and Raman spectra of dideuterated acetylene containing one 13C atom, 13C12CD2, have been recorded and analysed to obtain detailed information on the fundamental ν 2 band and associated combination and hot bands. Infrared spectra were recorded at 4 × 10−3 cm−1 resolution in the region 1150−2900 cm−1, which contains combination and hot bands from the ground and the bending v 4 = 1 and v 5 = 1 states. The Q-branches of the ν 2 fundamental and associated hot bands (ν 2 + ν 4 − ν 4, ν 2 + ν 5 − ν 5, ν 2 + 2ν 4 − 2ν 4, ν 2 + 2ν 5 − 2ν 5 and ν 2 + ν 4 + ν 5 − (ν 4 + ν 5)) were recorded using inverse Raman spectroscopy, with an instrumental resolution of about 3 × 10−3 cm−1. In addition, the observation of the 2ν 2 − ν 2 Raman band was carried out populating the v 2 = 1 state by stimulated Raman pumping. In total, 11 Raman and 9 infrared bands were analysed, involving all the l-vibrational components of the excited stretching−bending manifolds up to v t  = v 4 + v 5 = 2. A simultaneous analysis of all infrared and Raman assigned transitions has been performed on the basis of a theoretical model which takes into account the rotation and vibration l-type resonances within each vibrational manifold and the Darling−Dennison anharmonic resonance between the ν 2 + 2ν 4 and ν 2 + 2ν 5 states. The parameters obtained reproduce the assigned transition wavenumbers with a standard deviation of the same order of magnitude as the experimental uncertainty. [ABSTRACT FROM PUBLISHER]

Abstract: The high-resolution infrared spectrum of two partially deuterated isotopologues of acetylene, H12C13CD and H13C12CD, has been recorded by Fourier transform spectroscopy in the range 450–1850cm−1. The bending fundamental bands and a number of overtone, combination and hot bands have been identified for both isotopomers. In total, 17 vibrational bands for H12C13CD and 18 bands for H13C12CD were analyzed, involving all the l-vibrational components of the excited bending states up to νt = ν 4 + ν 5 =2. The data pertaining to each molecule were analyzed together with the pure rotational transitions recorded in the millimeter- and sub-millimeter-wave frequency ranges and the ν 5 ← ν 4 band available in the literature. The model Hamiltonian adopted for the analysis takes into account the usual vibration and rotation l-type resonances. The ground state and 9 vibrationally excited states have been characterized for each isotopomer. The spectroscopic parameters obtained from the fits reproduce 1617 transitions for H12C13CD and 1613 transitions for H13C12CD, with standard deviations of the fit equal to 0.00038cm−1 and 0.00032cm−1, respectively. [Copyright &y& Elsevier]

Abstract: High resolution infrared spectra of 121SbHD2 and 123SbHD2 have been studied in the region of , the Sb–H stretching fundamental, from 1780 to 1990cm−1. The stretching overtone band of 123SbHD2, located in the 3640–3790cm−1 range, has also been investigated. The SbHD2 molecule is an asymmetric rotor of Cs symmetry with the asymmetry parameter κ =0.61. The band is of hybrid type, formed by strong C-type and weak B-type transitions, and almost unperturbed. For 123SbHD2, 2092 transitions have been assigned: 70% of these belong to the C component, the other 30% are of B-type. The assigned transitions have been fitted using a Watson type S-reduced Hamiltonian in the representation, with a standard deviation of the fit σ =0.45×10−3 cm−1. In order to determine the ground state parameters all possible ground state combination differences (GSCD) have been generated from the transitions. In total, 3942 GSCD up to = 27, =25, and =20 have been fitted with σ =0.52×10−3 cm−1. Only C-type transitions have been observed in the weak overtone band. The 556 assigned transitions have been fitted with σ =2.6×10−3 cm−1 using the same Hamiltonian as for . In the band of 121SbHD2 771 C-type transitions have been assigned, and the spectroscopic constants obtained from a fit with σ =0.70×10−3 cm−1. Using 618 GSCD the ground state spectroscopic constants of 121SbHD2 have been derived with σ =1.0×10−3 cm−1. The molecular parameters for the ground and the states of the two isotopologues agree well. The quartic theoretical ab initio force field of SbH3 has been used to predict all relevant spectroscopic parameters for 123SbHD2, 121SbHD2, 123SbH2D, and 121SbH2D. Relations between the harmonic frequencies and between the anharmonicity constants obtained in the expanded local mode theory, for the XH3 →XH2D/XHD2 isotopic substitution, have been compared with those obtained in the present study. [Copyright &y& Elsevier]

Abstract: The high resolution infrared spectrum of the mono-isotopic species 123SbD3 has been studied in the regions of the first and second Sb–D stretching overtones, from 2600 to 2800cm−1 and from 3900 to 4100cm−1, respectively. In both regions only two almost degenerate bands of similar intensity have been observed, one parallel and the other perpendicular, corresponding to the low-lying states in the manifolds of the excited vibrational states. These bands have been identified as 2ν 1(A 1)/ν 1 + ν 3(E) in the first overtone and 3ν 1(A 1)/2ν 1 + ν 3(E) in the second overtone band system. About 1700 transitions with have been assigned to the 2ν 1(A 1)/ν 1 + ν 3(E) and about 700 with to the 3ν 1(A 1)/2ν1+ ν 3(E) dyad. The transitions assigned to each dyad have been fitted simultaneously since the A 1/E excited states are affected by strong Coriolis and k-type perturbations treated explicitly in the model. Eventually, the extent to which the parameters resulting from the analyses fulfill the local mode theory requirements has been evaluated. Differently from SbH3, the deuterated species does not reach true local mode behavior, even in the second overtone. [Copyright &y& Elsevier]

Abstract: The high-resolution infrared spectra of the monoisotopic species F35Cl16O3, F37Cl16O3, F35Cl18O3 and F37Cl18O3 have been studied in the region of the 2ν5 overtones, from 1100 to 1200cm−1. Both the parallel and the perpendicular components are clearly observed in the spectra, their origins differing by about 0.4cm−1. In each spectrum about 2000 transitions have been assigned, 35% of them belonging to . The parallel and perpendicular bands in each manifold have been analyzed separately since no evidence of perturbations has been observed. The rovibration parameters of the v5 =2, l 5 =0 and v5 =2, excited states have been obtained. For the four species combining the and band origins with those of the ν 5 fundamentals the harmonic wavenumbers, , and the x 55 and g 55 anharmonicity constants have also been derived. [Copyright &y& Elsevier]

Abstract: The second CH stretching overtone of cyanoacetylene, HC3N, near 9700cm−1 has been recorded by Fourier Transform Spectroscopy (FTS) and by Intracavity Laser Absorption Spectroscopy (ICLAS) with a Vertical External Cavity Surface Emitting Laser (VECSEL). In total thirteen bands have been identified in the highly congested spectra and rotationally assigned. Their rovibrational spectroscopic parameters have been obtained from a fit of the line centers. [Copyright &y& Elsevier]

Forty cold bands and 29 hot bands are reported from the high resolution Fourier transform (FT) absorption spectrum of 13CH12CH, all leading to vibrational states located between 6750 and 9500 cm-1. Each of these bands has been vibrationally assigned and rotationally analysed. The band centres (νc), vibrational term values (Gv) and rotational constants are listed. [ABSTRACT FROM AUTHOR]

Abstract: The high resolution infrared spectra of monoisotopic F35Cl18O3 and F37Cl18O3 have been studied in the region of the ν 4 fundamentals, centered at 1278.3 and 1263.3cm−1, respectively. Large perturbations are observed in both bands due to a Fermi type anharmonic resonance with the ν 2 + ν 5 combination bands, centered at 1270.7cm−1 in F35Cl18O3 and 1257.3cm−1 in F37Cl18O3. In particular, they affect the kl >0 levels of the v 4 =1 and v 2 = v 5 =1 states which cross at kl ⩾18 in F35Cl18O3 and kl ⩾3 in F37Cl18O3, due to the opposite values of and . The Δl =Δk =±2 and Δl =0, Δk =±3 essential resonances are also effective in the excited states of the dyad in F35Cl18O3, while in F37Cl18O3 only the Δl =Δk =±2 one is active. In the spectrum of F35Cl18O3 3423 transitions have been assigned, 10% of them belonging to ν 2 + ν 5. The rovibrational parameters and the interaction constants between the v 4 =1 and v 2 = v 5 =1 levels have been obtained. The depertubed band origins of ν 4 and ν 2 + ν 5 are 1277.310567(165) and 1271.753733(195)cm−1, respectively, and the anharmonic resonance constant is 2.804416(153)cm−1. For F37Cl18O3, 3022 transitions have been assigned, 38% belonging to the ν 2 + ν 5 combination band. The depertubed band origins are 1260.856338(123) and 1259.872338(134)cm−1, for ν 4and ν 2 + ν 5 and the constant is 2.9350669(405)cm−1. The equilibrium geometry of perchloryl fluoride, r e (ClO)=139.7(3)pm, r e (ClF)=161.0(5)pm, and α e (OClO)=115.7(4)degree, has been determined using the A e and B e equilibrium constants of the four symmetric isotopologues of perchloryl fluoride, F35/37Cl16O3 and F35/37Cl18O3. [Copyright &y& Elsevier]

Abstract: The ν 1(A1), Si–H stretching, ν 2(A1) and ν 4(E), Si–D stretchings, fundamental bands of HSiD3 have been recorded at an effective resolution of ca. 0.003cm−1 between 2080 and 2280cm−1 and between 1480 and 1720cm−1, respectively. Ro-vibrational transitions of the H28SiD3 isotopologue have been assigned in the two spectral ranges, about 700 belonging to ν 1, with J′ up to 25 and K up to 21, and about 1600 to the ν 2/ν 4 dyad, with J′ up to 24 and K′ up to 19. The spectra of all the bands evidence the existence of several perturbations. The transitions of ν 1 have been analyzed either neglecting or including in the model A1/E Coriolis-type interactions with nearby dark states. The υ 2 =1 and υ 4 =1 states have been fitted simultaneously taking into account several ro-vibrational interactions between them and, in addition, with the υ 5 =2, l =0 component, and with few other close dark states. The standard deviation of the fit for both ν 1 and the ν 2/ν 4 dyad is, however, more than one order of magnitude larger than the estimated experimental precision and is independent on the adopted model. [Copyright &y& Elsevier]

Abstract: The infrared spectra of the 2ν 1, 2ν 2 and 2ν 3 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 2120cm−1 (2ν 1), from 1390 to 1430cm−1 (2ν 2) and from 1070 to 1100cm−1 (2ν 3). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v 1 =2, v 2 =2 and v 3 =2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067cm−1. The 2ν 1 overtones of F35Cl16O3 and F37Cl16O3 are perturbed by an A 1/E Coriolis resonance between the v 1 =2 state and one E component of the v 4 =1, v 6 =2 manifold. The 2ν 2 of F37Cl18O3 is perturbed by the same kind of interaction involving the v 1 = v 6 =1 (E) state, at about 1396cm−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 x 11, x 22, x 33 of all the studied isotopologues of FClO3, x 46 of F35Cl16O3, x 46 + g 46 of F37Cl16O3 and x 16 of F37Cl18O3, have been derived. [Copyright &y& Elsevier]

A total of 3155 vibration-rotation line positions providing accurate information on all known vibration-rotation states up to 3000 cm-1 in 12C2H2 were gathered from the literature. An additional 966 lines were assigned on new spectra. The full data set was simultaneously fitted using an appropriate Hamiltonian, with 85 refined parameters. A dimensionless standard deviation equal to 0.86, accounting for 92% of the lines, was achieved. The vibrational transition dipole moment of the υ5 = 1 ← υ4 = 1 band observed in the far-infrared was estimated to be |μ5←4| = 0.55 D with 20% accuracy, from absolute intensity measurements for a few Q-branch lines. [ABSTRACT FROM AUTHOR]

Abstract: The high resolution infrared spectrum of mono-isotopic F37Cl16O3 has been studied in the regions of ν 1, ν 2, ν 4 and ν 2 + ν 5 bands, centered at 1060.20, 707.16, 1301.71 and 1292.15cm−1, respectively. The ν 1 and ν 2 parallel bands are unperturbed so their analysis was straightforward and 3355 and 2433 transitions were assigned, respectively. The band origins, the rotational and centrifugal molecular constants in the v 1 =1 and v 2 =1 states have been determined, with standard deviation of the fits σ =0.00019 and 0.00018cm−1. The ν 4 fundamental is affected by an anharmonic resonance with the ν 2 + ν 5 combination band. The kl >0 sublevels cross at kl ⩾27 because of the opposite values of and . The anharmonic resonance constant cm−1 has been derived. The Δl =Δk =±2 and Δl =0, Δk =±3 essential resonances have been found to be effective in ν 4, while in ν 2 + ν 5 only the Δl =Δk =±2 one was active. A total of 5721 transitions have been assigned, 25% of them belonging to ν 2 + ν 5. The rovibrational parameters and the interaction constants of F37Cl16O3 have been obtained. The standard deviation of the fit is 0.0006cm−1, six times the estimated data precision. The equilibrium geometry of perchloryl fluoride has been determined from the A e and B e constants of F35Cl16O3 and F37Cl16O3. Using the A 0 and B 0 constants of all the symmetric species the r 0 geometry has also been derived. [Copyright &y& Elsevier]

The infrared spectrum of 13CH12CH has been recorded in the 9500–10000 cm−1 wavenumber region by Fourier transform spectroscopy. Twelve Σ+–Σ+ and one ‘perturbation allowed’ Δ–Σ+ cold bands, and four Π–Π hot bands have been identified. All these bands have been rotationally analysed and vibrationally assigned. They mainly involve triple excitations of the CH stretching modes. The relative intensities have been measured. Local interaction patterns are identified and discussed. Line wavenumbers from the two strongest bands observed in the range are listed. [ABSTRACT FROM AUTHOR]

The infrared spectrum of 13CH12CH has been recorded in the 9500–10000 cm−1 wavenumber region by Fourier transform spectroscopy. Twelve Σ+–Σ+ and one ‘perturbation allowed’ Δ–Σ+ cold bands, and four Π–Π hot bands have been identified. All these bands have been rotationally analysed and vibrationally assigned. They mainly involve triple excitations of the CH stretching modes. The relative intensities have been measured. Local interaction patterns are identified and discussed. Line wavenumbers from the two strongest bands observed in the range are listed. [ABSTRACT FROM AUTHOR]

Thirty four cold bands and 37 hot bands are reported from the high resolution FT absorption spectrum of 13 CH 12 CH, all leading to vibrational states located between 3800 and 6750?cm -1 . Each band has been vibrationally assigned and rotationally analysed. The band centres and rotational constants are listed. [ABSTRACT FROM AUTHOR]

The high resolution infrared spectrum of 123 SbD 3 has been recorded in the 20-350 cm -1 range and in the regions of the ν 1 , ν 3 and ν 2 , ν 4 fundamental bands centred at 1350 and 600 cm -1 , respectively. Splitting of the K ′′ = 3, 6 lines have been observed both in the rotation and ro-vibration spectra. A large number of 'perturbation allowed' transitions with selection rules Δ( k - l ) = ± 3, ± 6, and ± 9 have been identified in all fundamental bands. Accurate ground state molecular parameters have been determined by means of a simultaneous fit of the rotational transitions and about 12 000 ground state combination differences from the infrared bands. The A and B reductions of the rotational Hamiltonian provided almost equivalent results. The molecular parameters of the ν i = 1 ( i = 1 - 4) states were obtained as a result of the simultaneous analysis of the ν 1 (A 1 )/ν 3 (E) stretching and of the ν 2 (A 1 )/ν 4 (E) bending dyads. In fact, the corresponding excited states are affected by strong perturbations due to rovibrational interactions of Coriolis and k -type that have been treated explicitly in the model adopted for the analysis. Improved effective ground state and equilibrium geometries were determined for the molecule and compared to those of 123 SbH 3 . Ab initio calculations at the coupled cluster CCSD(T) level with an energy-consistent large-core pseudopotential and large basis sets were carried out to determine the equilibrium structure, the anharmonic force field, and the associated spectroscopic constants of 123 SbH 3 and 123 SbD 3 . The theoretical results are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]