The infrared spectrum of C3O2: The interaction between ν7 and the ν2 and ν4 vibrations

The 3ν¹₇, 3ν³₇, and 4ν⁰₇ hot bands of the ν₄ fundamental of C₃O₂ in the 1580 cm^?1 region were analyzed from tunable diode laser spectra and the ground state to ν₄ + 2ν⁰₇ band at 1644 cm^?1 from Fourier transform spectra (FTS). The molecular constants for all of the v₄ 1 ← 0 bands as well as the intensity of the ν₀ + 2ν⁰₇ sum band relative to the ν₄ fundamental were in agreement with the predictions of the model of Weber and Ford. FTS spectra at 0.05 cm^?1 resolution were obtained of the sum and difference bands of ν₂ with ν₇ in the 750–900 cm^?1 region. Sharp Q branches occur for each ν₇ state in the sum bands, but only a number of R-branch bandheads and no recognizable Q branches in the difference bands. Assignments of the sum band Q branches through v₇ = 6 were made and molecular constants were determined for the ν₂ + ν¹₇ ← 0 transition at 819.7 cm^?1. The ν₇ potential function in the v₂ = 1 state was found to have a 1.2 cm^?1 barrier with a minimum at α = 4.9°, where 2α is the angular deviation from linearity. The Q-branch positions predicted from the calculated energy levels fit those observed within several cm^?1.     

A Vibrational Spectroscopic Study of the Sulfate Mineral Glauberite

The mineral glauberite is one of many minerals formed in evaporite deposits. The mineral glauberite has been studied using a combination of scanning electron microscopy with energy dispersive X-ray analysis and infrared and Raman spectroscopy. Qualitative chemical analysis shows a homogeneous phase, composed by sulfur, calcium, and sodium. Glauberite is characterized by a very intense Raman band at 1002 cm^?1 with Raman bands observed at 1107, 1141, 1156, and 1169 cm^?1 attributed to the sulfate ν₃ antisymmetric stretching vibration. Raman bands at 619, 636, 645, and 651 cm^?1 are assigned to the ν₄ sulfate bending modes. Raman bands at 454, 472, and 486 cm^?1 are ascribed to the ν₂ sulfate bending modes. The observation of multiple bands is attributed to the loss of symmetry of the sulfate anion. Raman spectroscopy is superior to infrared spectroscopy for the determination of glauberite.     

Vibrational Spectroscopic Characterization of the Sulphate-Carbonate Mineral Burkeite: Implications for Evaporites

Burkeite formation is important in saline evaporites and in pipe scales. Burkeite is an anhydrous sulphate-carbonate with an apparent variable anion ratio. Such a formula with two oxyanions lends itself to vibrational spectroscopy. Two symmetric sulphate stretching modes are observed, indicating at least at the molecular level the nonequivalence of the sulphate ions in the burkeite structure. The strong Raman band at 1065 cm^?1 is assigned to the carbonate symmetric stretching vibration. The series of Raman bands at 622, 635, 645, and 704 cm^?1 are assigned to the ν₄ sulphate bending modes. The observation of multiple bands supports the concept of a reduction in symmetry of the sulphate anion from T _d to C _3v or even C _2v.     

Simultaneous Analysis of Rovibrational and Rotational Spectra of thev5= 1 andv8= 1 Vibrational Levels of Propyne

The microwave and submillimeter wave spectra of propyne between 17 and 358 GHz were measured and the rotational transitions in thev₈= 1 excited vibrational state of the CH₃rocking vibration were assigned. About 1050 wavenumbers of the ν₈vibration–rotation fundamental band and about 600 wavenumbers of the ν₅fundamental band of the[formula]stretching vibration were assigned from the infrared spectrum between 910 and 1130 cm⁻¹which was used previously (G. Graneret al., J. Mol. Spectrosc.161,80–101 (1993)) in the analysis of the combinationv₉=v₁₀= 1 and thev₁₀= 3 overtone levels (ν₉being the[formula]bending and ν₁₀the[formula]bending vibrations). The rovibrational and rotational data corresponding to the two fundamental levels were analyzed simultaneously in least-squares fits using a model which treats together all the vibrational levels in the region around 1000 cm⁻¹with their strong anharmonic and vibration–rotation resonances. The refined parameters reproduce the infrared and submillimeter wave data of thev₅= 1 level with standard deviations of 0.32 × 10⁻³cm⁻¹and 59 kHz, respectively, while for thev₈= 1 level the standard deviations were 0.41 × 10⁻³cm and 290 kHz. The refined parameters of the combination and overtone levels provide reliable predictions for future submillimeter wave studies.     

The Stimulated Raman Spectrum of Cyanogen

The Raman spectrum of cyanogen¹²C₂¹⁴N₂has been investigated at nearly Doppler resolution by means of the Stimulated Raman technique. The regions around theQbranches of the ν₁(2330 cm⁻¹) and ν₂(845 cm⁻¹) vibrations have been recorded. Besides the fundamentals, hot bands arising fromv₅= 1,v₅= 2, andv₄= 1 have been observed. The spectra have been analyzed, and rotational constants for the excited states have been obtained. Computer simulations of the Raman contours have been carried out as a test of the assignments.     

A Vibrational Spectroscopic Study of the So-Called Healing Mineral Papagoite CaCuAlSi2O6(OH)3

ABSTRACT

Papagoite is a silicate mineral named after an American Indian tribe and was used as a healing mineral. Papagoite CaCuAlSi₂O₆(OH)₃ is a hydroxy mixed anion compound with both silicate and hydroxyl anions in the formula. The structural characterization of the mineral papagoite remains incomplete. Papagoite is a four-membered ring silicate with Cu²⁺ in square planar coordination.

The intense sharp Raman band at 1053 cm^?1 is assigned to the ν₁ (A _1g) symmetric stretching vibration of the SiO₄ units. The splitting of the ν₃ vibrational mode offers support to the concept that the SiO₄ tetrahedron in papagoite is strongly distorted. A very intense Raman band observed at 630 cm^?1 with a shoulder at 644 cm^?1 is assigned to the ν₄ vibrational modes.

Intense Raman bands at 419 and 460 cm^?1 are attributed to the ν₂ bending modes.

Intense Raman bands at 3545 and 3573 cm^?1 are assigned to the stretching vibrations of the OH units. Low-intensity Raman bands at 3368 and 3453 cm^?1 are assigned to water stretching modes. It is suggested that the formula of papagoite is more likely to be CaCuAlSi₂O₆(OH)₃ · xH₂O. Hence, vibrational spectroscopy has been used to characterize the molecular structure of papagoite.     

Vibrational Spectroscopic Characterization of the Arsenate Mineral Barahonaite: Implications for the Molecular Structure

The mineral barahonaite is in all probability a member of the smolianinovite group. The mineral is an arsenate mineral formed as a secondary mineral in the oxidized zone of sulphide deposits. We have studied the barahonaite mineral using a combination of Raman and infrared spectroscopy. The mineral is characterized by a series of Raman bands at 863 cm^?1 with low wavenumber shoulders at 802 and 828 cm^?1. These bands are assigned to the arsenate and hydrogen arsenate stretching vibrations. The infrared spectrum shows a broad spectral profile. Two Raman bands at 506 and 529 cm^?1 are assigned to the triply degenerate arsenate bending vibration (F ₂, ν₄), and the Raman bands at 325, 360, and 399 cm^?1 are attributed to the arsenate ν₂ bending vibration. Raman and infrared bands in the 2500–3800 cm^?1 spectral range are assigned to water and hydroxyl stretching vibrations. The application of Raman spectroscopy to study the structure of barahonaite is better than infrared spectroscopy, probably because of the much higher spatial resolution.     

Torsional tunneling splittings in the v4 = 1 excited torsional state of Si2H6: analysis of hot bands accompanying fundamental transitions in the high resolution infrared spectrum

The (ν₄?+?ν₆)???ν₄, (ν₄?+?ν₈)???ν₄ and (ν₄?+?ν₉)???ν₄ hot infrared systems of disilane (Si₂H₆) have been analysed at high resolution, and the values of the relative vibration–rotation–torsion parameters have been determined. The torsional splitting is about 0.500?cm^?1 in the ν₄ and ν₄?+?ν₆ states, and decreases strongly in the vibrationally degenerate upper states ν₄?+?ν₈ (about 0.0272?cm^?1 on average) and ν₄?+?ν₉ (about 0.3019?cm^?1), consistent with theoretical predictions. Comparison between the vibrational wavenumbers of cold transitions and hot transitions originating in the excited torsional state v₄?=?1 allows one to determine the change of the fundamental torsional frequency ν₄ caused by the excitation of small amplitude vibrations. A remarkable increase in ν₄ of about 8.599?cm^?1 is found in the v₉?=?1 state (E_1d SiH₃-rocking mode, asymmetric to inversion in the staggered geometry), and this corresponds to an increase in the torsional barrier height in this excited fundamental vibrational state by about 48.77?cm^?1. The mechanism responsible for the decrease of the torsional splittings in the degenerate vibrational states is briefly outlined by means of second-order perturbation theory, using torsion-hindered vibrational basis functions of E_1d and E_2d symmetries for the degenerate modes.     

The infrared spectrum of 12C2HD: the bending states up to υ4 +υ5 =3

The infrared spectrum of ¹²C₂HD has been recorded at high resolution between 450 and 2100?cm^?1 by Fourier transform spectroscopy. The ν₄ and ν₅ bending fundamental bands together with overtones, combination bands and associated hot bands involving modes up to υ_tot?=?υ₄?+?υ₅?=?3 have been identified. Altogether, 43 vibrational bands have been analysed, leading to the spectroscopic characterization of the ground state and of 18 vibrationally excited states. They include all the components of the vibrational manifolds up to υ_tot?=?3, with the exception of the υ₄?=?3, ??=?±3 state. A simultaneous fit of all the assigned transitions has been performed. The adopted model includes vibration and rotation ?-type interaction resonances. The determined spectroscopic parameters reproduce the assigned wavenumber transitions with RMS values close to the estimated experimental uncertainties.     

High-resolution Fourier-transform infrared spectroscopy of the ν1 and ν8 fundamental bands of sulphur tetrafluoride (SF4)

The vibration-rotation spectra of the ν₁ and ν₈ fundamental bands of ³²SF₄ have been observed using Fourier-transform infrared spectroscopy. The band centre of the c-type ν₁ symmetric sulphur-equatorial-fluorine stretching vibration was observed at 891.6 cm^?1 and that for the b-type ν₈ asymmetric sulphur-equatorial-fluorine stretching vibration at 864.6 cm^?1. In total, 2044 rovibrational transitions have been assigned. Analysis of the spectra showed that the rotational states of the ν₁ = 1 and ν₈ = 1 upper vibrational levels are coupled by an a-type Coriolis interaction. This coupling has been treated both using perturbation theory and by the explicit inclusion of an appropriate Hamiltonian matrix element in a combined fit of the data for both bands. Spectroscopic parameters have been determined for the ground, ν₁ = 1 and ν₈ = 1 vibrational levels. Weaker transitions resulting from difference bands and the fundamental bands of the ³⁴SF₄ isotopomer have been identified but could not be assigned, because of the density of lines in the room-temperature spectrum. The possibility that discrepancies between the observed and predicted spectra of the ν₁ fundamental may result from either a Coriolis interaction with the states of another vibrational level, or the effects of intramolecular exchange of axial and equatorial fluorine atoms is considered. The discussion is supported by theoretical calculations which show that the likely path for intramolecular exchange is via a C _4v transition state.     

High resolution infrared synchrotron study of CH2D81Br: ground state constants and analysis of the ν5, ν6 and ν9 fundamentals

The high resolution infrared absorption spectrum of CH₂D⁸¹Br has been recorded by Fourier transform spectroscopy in the range 550–1075?cm^?1, with an unapodized resolution of 0.0025?cm^?1, employing a synchrotron radiation source. This spectral region is characterized by the ν₆ (593.872?cm^?1), ν₅ (768.710?cm^?1) and ν₉ (930.295?cm^?1) fundamental bands. The ground state constants up to sextic centrifugal distortion terms have been obtained for the first time by ground-state combination differences from the three bands and subsequently employed for the evaluation of the excited state parameters. Watson's A-reduced Hamiltonian in the I^r representation has been used in the calculations. The ν ₆?=?1 level is essentially free from perturbation whereas the ν ₅?=?1 and ν ₉?=?1 states are mutually interacting through a-type Coriolis coupling. Accurate spectroscopic parameters of the three excited vibrational states and a high-order coupling constant which takes into account the interaction between ν₅ and ν₉ have been determined.     

A Raman spectroscopic study of the different vanadate groups in solid‐state compounds—model case: mineral phases vésigniéite [BaCu3(VO4)2(OH)2] and volborthite [Cu3V2O7(OH)2·2H2O]

Raman spectroscopy has been used to study vanadates in the solid state. The molecular structure of the vanadate minerals vésigniéite [BaCu₃(VO₄)₂(OH)₂] and volborthite [Cu₃V₂O₇(OH)₂·2H₂O] have been studied by Raman spectroscopy and infrared spectroscopy. The spectra are related to the structure of the two minerals. The Raman spectrum of vésigniéite is characterized by two intense bands at 821 and 856 cm⁻¹ assigned to ν₁ (VO₄)³⁻ symmetric stretching modes. A series of infrared bands at 755, 787 and 899 cm⁻¹ are assigned to the ν₃ (VO₄)³⁻ antisymmetric stretching vibrational mode. Raman bands at 307 and 332 cm⁻¹ and at 466 and 511 cm⁻¹ are assigned to the ν₂ and ν₄ (VO₄)³⁻ bending modes. The Raman spectrum of volborthite is characterized by the strong band at 888 cm⁻¹, assigned to the ν₁ (VO₃) symmetric stretching vibrations. Raman bands at 858 and 749 cm⁻¹ are assigned to the ν₃ (VO₃) antisymmetric stretching vibrations; those at 814 cm⁻¹ to the ν₃ (VOV) antisymmetric vibrations; that at 508 cm⁻¹ to the ν₁ (VOV) symmetric stretching vibration and those at 442 and 476 cm⁻¹ and 347 and 308 cm⁻¹ to the ν₄ (VO₃) and ν₂ (VO₃) bending vibrations, respectively. The spectra of vésigniéite and volborthite are similar, especially in the region of skeletal vibrations, even though their crystal structures differ. Copyright © 2011 John Wiley & Sons, Ltd.     

The infrared spectrum of 12C2HD: the stretching–bending combination bands in the 1800–4700 cm−1 region

The infrared spectrum of ¹²C₂HD has been observed between 1800 and 4700?cm^?1 by Fourier transform spectroscopy. The ν₁, ν₂ and ν₃ absorption bands and the associated hot and combination bands involving the bending modes up to υ_t?=?υ₄?+?υ₅?=?2 have been investigated. Altogether, 60 vibrational bands were analysed, leading to the spectroscopic characterization of 31 vibrationally excited states. Several perturbations have been observed, but the transitions involving the perturbing states have not been detected. As a consequence, an appropriate treatment of the vibrational or ro-vibrational interactions has not been possible. A tentative assignment of the perturbing states has been proposed. Eventually, global fits for each fundamental vibration and its associated cold and hot bands have been performed.     

The infrared spectrum of 13C2H2 in the 60–2600 cm−1 region: bending states up to v 4 + v 5 = 4

The vibration–rotation spectra of ¹³C substituted acetylene, ¹³C₂H₂, have been recorded in the region between 60 and 2600?cm^?1 at an effective resolution ranging from 0.001 to 0.006?cm^?1. Three different instruments were used to collect the experimental data in the extended spectral interval investigated. In total 9529 rotation vibration transitions have been assigned to 101 bands involving the bending states up to v _tot?=?v ₄?+?v ₅?=?4, allowing the characterization of the ground state and of 33 vibrationally excited states. All the bands involving states up to v _tot?=?3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model, larger discrepancies between observed and calculated values have been obtained for transitions involving states with v _tot?=?4. These could be satisfactorily reproduced only by adopting a set of effective constants for each vibrational manifold, in addition to the previously determined parameters, which were constrained in the analysis.     

High resolution FTIR study of the ν5 and ν6 bands of CH2D35Cl: analysis of resonances and determination of ground and upper state constants

The isotopically pure form of methyl chloride, CH₂D³⁵Cl, was synthesized and investigated by Fourier transform infrared spectroscopy with an unapodized resolution of 0.004?cm^?1 in the range 650–900?cm^?1, the region of the lowest fundamentals ν₅ (827?cm^?1) and ν₆ (714?cm^?1). These distinct bands have been analysed in detail in the P-, Q- and R-branches. In spite of their expected a/b-hybrid nature, both envelopes show the peculiar characteristic of only a-type bands of near prolate asymmetric top molecules. Ground state parameters have been determined for the first time through ground state combination differences from both bands. Parameters of the excited vibrational states and coupling constants have been obtained using a model which accounts for c-type Coriolis interaction and ΔK_a?=?±?2 anharmonic resonance.     

The Infrared Spectrum of CCH2: The Bending States up to v4+v5=4

The vibration-rotation spectra of ¹³C monosubstituted acetylene, ¹²C¹³CH₂, have been recorded in the region between 450 and 3200 cm⁻¹ with an effective resolution ranging from 0.004 to 0.006 cm⁻¹. A total of about 5300 rovibrational transitions have been assigned to 53 bands involving the bending states up to v_t=v₄+v₅=4, allowing the characterization of the ground state and of 30 vibrationally excited states. All the bands involving states up to v_t=3 have been analyzed simultaneously by adopting a model Hamiltonian which takes into account the vibration and rotation l-type resonances. The derived spectroscopic parameters reproduce the transition wavenumbers with a RMS value of the order of the experimental uncertainty. Using the same model larger discrepancies between observed and calculated values have been obtained for transitions involving states with v_t=4. These could be satisfactorily reproduced by only adopting, in addition to the previously determined parameters which were constrained in the analysis, a set of effective constants for each vibrational manifold.     

The infrared spectrum of DCCF in the 320–850 cm−1 region: bending states up to υ4+υ5 = 3

Infrared spectra of deuterated monofluoroacetylene, DCCF, have been recorded in the region between 320 and 850 cm^?1 at an effective resolution ranging from 0.0024 to 0.0031 cm^?1. In total, 6650 rotation vibration transitions were assigned to 37 bands involving the bending states with v₄ + v₅ and |l₄+l₅|, respectively, up to 3, allowing the characterisation of the ground state and of 18 vibrationally excited states. The vν₅ bending fundamental has been studied for the first time. In addition, the difference band v₃ ← v₄ has been detected and analysed. All the assigned transitions have been fitted simultaneously by adopting a model Hamiltonian that takes into account the vibration and rotation l?type resonances. Rotational transitions in the ground and in bending excited states reported in the literature have been included in the global analysis. The set of 57 derived spectroscopic parameters reproduces 6130 infrared and 90 microwave and millimetre?wave transitions satisfactorily with root mean square values of 5.3 × 10^?4 cm^?1 and 77 kHz, respectively.     

The ν6, ν8 3ν4+ν12 infrared system of Si2H6 under high resolution: rotational and torsional analysis

A Fourier transform infrared spectrum of disilane has been measured at a Doppler limited resolution, and analysed in the region of the ν₆ and ν₈ fundamentals, from about 800 to 1020cm^?1. The torsional splittings are not resolved in the ν₆ band, showing that the splittings in the ν₆ = 1 state and in the ground state are almost identical. The torsional splittings in the reasonably unperturbed regions of the ν₈ fundamental are about 0.0146cm^?1, and a detailed rotation-torsion analysis shows that the intrinsic splittings in the ν₈ = 1 state are smaller than in the ground state by this amount. An intrinsic torsional splitting about 0.0150 cm^?1 is estimated in the vibrational ground state and in the ν₆ = 1 state, and almost vanishing in the ν₈ = 1 state (about 0.0004cm^?1), with a barrier height around 407cm^?1. This is in agreement with the expectation from theory. The ν₈ band, beyond a moderate x, y-Coriolis coupling with ν₆, is affected by several perturbations, also selective in the torsional components. The 3ν₄ + v¹² combination, with three quanta of the torsional mode excited and large torsional splittings, is the main perturber, causing both Fermi and Coriolis resonances in several regions of the spectrum. The vibrational origins of all four torsional components of 3ν₄ + v¹² were determined. Other perturbative effects are attributed to the systems 2ν₃ + ν₄, and ν₄ + 24₉(E + A). The spectrum was numerically analysed, and the relevant vibration-rotation-torsion parameters were determined.     

High-resolution rovibrational analysis of vibrational states of A2 symmetry of the dideuterated methane CH2D2: the levels ν 5 and ν 7 + ν 9

The infrared spectrum of the CH₂D₂ molecule has been measured in the region 900–1500?cm^?1 on a Bomem DA002 Fourier transform spectrometer with a resolution of 0.0024?cm^?1 (FWHM, unapodized). Transitions belonging to the hot bands ν ₇?+?ν₉?ν ₇, ν₇?+?ν₉? ν ₉, ν₅?+?ν₇?ν₅, and ν₅?+?ν₉?ν₅ were extracted from the recorded spectra to determine the rovibrational energies of the A₂ symmetry vibrational states (v ₇?=?v ₉?=?1) at 2329.698?cm^?1 and (v ₅ ?=?1) at 1331.409?cm^?1. Vibrational energies as well as rotational and centrifugal distortion parameters of the (v ₇?=?v ₉=1) and (v ₅?=?1) states were determined that reproduce the experimental rovibrational energy levels of the (v ₇?=?v ₉?=?1) and (v ₅?=?1) vibrational states with a d _rms deviation of 0.0017 and 0.0006?cm^?1, respectively. The results are discussed in relation to the equilibrium structure of methane, which is redetermined here from the experimental data, and in relation to its potential hypersurface and anharmonic vibrational dynamics.     

High resolution infrared spectrum of the ν4 band of DCCF

The bending vibration-rotation band ν₄ of DCCF was studied. The measurements were carried out with a Fourier spectrometer at a resolution of about 0.03 cm^?1. The constants B₀=0.29141(1)cm^?1, α₄=?5.02(2)×10^?4cm^?1, q₄=4.52(3)×10^?4cm^?1, and D₀=9.2(4)×10^?8cm^?1 were derived. The rotational analysis of the “hot” bands 2ν₄(Δ) ← ν₄(II) and 2ν₄(Σ⁺) ← ν₄(II) was performed. In addition, the “hot” bands ν₄ + ν₅ ← ν₅ were assigned. A set of vibrational constants involved was derived.