High resolution FTIR spectrum of the nu1 band of DCOOD

Accurate spectral information on formic acid has wide application to radioastronomy since it was the first organic acid found in interstellar space. In this work, the infrared absorption spectrum of the nu1 band of deuterated formic acid (DCOOD) has been measured on a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2560-2690 cm(-1) with a resolution of 0.004 cm(-1). A total of 292 infrared transitions have been assigned in this hybrid type A and B band centred at 2631.8736 +/- 0.0004 cm(-1). The assigned transitions have been fitted to give a set of eight rovibrational constants for the nu1 = 1 state with a standard deviation of 0.00078 cm(-1).     

Matrix isolation FTIR spectroscopical study of ethene secondary ozonide

A new method is used for the separation of ethene secondary ozonide (SOZ) from the other products of ethene ozonization reaction. The reaction was performed in the neat films of the reactants at 77 K. Ethene SOZ was separated from other products of the reaction by vacuum distillation at 190–210 K and analyzed by means of the matrix isolation IR absorption spectroscopy. Spectroscopic data from photolysis of the matrix isolated ozonide was used as an argument for assignment of the infrared spectral bands either to ethene SOZ or to other products of the reaction. The spectra of ethene SOZ isolated in the Ar matrix were analyzed by combining experimental results with the theoretical calculations performed at the MP2 6-311+G (3df, 3pd) level. A new assignment of some experimental fundamental bands is proposed taking in to account the Fermi resonance between CH stretch and the five membered ring vibrations. For the first time more than 30 weak infrared absorption bands were observed and assigned to various combination vibrations and overtones. By using new spectral information concerning the overtones and the combination bands it is concluded that the dissociation of unstable ethene SOZ involving breaking of any of the four CO bonds of the five membered ring of ethene SOZ has low probability. Dissociation of the ring starts from breaking of the OO bond.      

High resolution spectroscopy of the nu(3) band of DCOOD

The rotation-vibration spectrum of DCOOD has been recorded in the carbonyl stretch (nu(3)) region. Using a standard S-reduced Watson Hamiltonian in the I(r) representation, 225 lines could be fitted to a vibrational-rotational band. A full set of molecular constants was obtained. The nu(3) band is found to be strongly perturbed in the K(a): 1<--1 and K(a): 2<--2 subband. The perturbation is attributed to a Fermi resonance with the 2nu(8) overtone band and Coriolis coupling to a combination band (nu(4)+nu(7)). The band center is determined to be 1725.1218(1) cm(-1) which is more than 10 cm(-1) shifted compared to previous studies.     

High-resolution infrared study of vinyl fluoride in the 750-1050 cm(-1) region: rovibrational analysis and resonances involving the nu8, nu10, and nu11 fundamentals

The FTIR spectra of CH2[double bond]CHF have been investigated in the nu(8), nu(10), and nu(11) region between 750 and 1050 cm(-1) at a resolution of about 0.002 cm(-1). The nu(8) vibration of symmetry species A' gives rise to an a/b-type hybrid band, while the nu(10) and nu(11) modes of A' ' symmetry produce c-type absorptions. Due to the proximity of their band origins, the three vibrations perturb each other by Coriolis and high-order anharmonic resonances. In particular, the interactions between the nu(8) and nu(10) modes are very strong and widespread with band origins separated by only 1.37 cm(-1). Besides the expected c-type characteristics, the nu(10) band shows a very intense pseudo a-type component caused by the strong first-order Coriolis resonances with the nu(8) state. Furthermore, the 2nu(9) "dark state" was found to be involved in the interacting band systems. The spectral analysis resulted in the identification of 3144, 3235, and 3577 transitions of the nu(8), nu(10), and nu(11) vibrations, respectively. Almost all the assigned data were simultaneously fitted using the Watson's A-reduction Hamiltonian in the Ir representation and the perturbation operators. The model employed includes nine types of resonances within the tetrad nu(8)/nu(10)/nu(11)/2nu(9) and a set of spectroscopic constants for the nu(8), nu(10), and nu(11) fundamentals as well as parameters for the "dark state" 2nu(9), and fourteen coupling terms have been determined.     

Fermi interaction between the nu1 and the nu2+4 nu(s) bands of Ar...DN2(+)

Two rotationally fully resolved vibrational bands have been assigned unambiguously to the linear deuteron bound Ar...DN(2) (+) complex by using ground state combination differences. The ionic complex is formed in a supersonic planar plasma expansion optimized and controlled by a mass spectrometer and is detected in direct absorption using tunable diode lasers and applying production modulation spectroscopy. The band origins are located at 2436.272 cm(-1) and at 2435.932 cm(-1) and correspond to the nu(1) band (NN stretch) and to the nu(2)+4 nu(s) combination band (DN and intermolecular stretch), respectively. The two bands overlap strongly and the large intensity of the combination band is explained in terms of a Fermi interaction. This interaction perturbs the observed transitions, particularly for low J values. Least-squares fitting yields values for the Fermi interaction parameters of F(0)=0.332 cm(-1) and F(J)=-0.001 46 cm(-1) and results in accurate rotational constants. These are discussed both from an experimental and a theoretical point of view.     

Observation of the pi...H hydrogen-bonded ternary complex, (C(2)H(4))(2)H(2)O, using matrix isolation infrared spectroscopy

FTIR absorption spectra of water-containing ethene:Ar matrices, with compositions of ethene up to 1:10 ethene:Ar, have been recorded. Systematically increasing the concentration of ethene reveals features in the spectra consistent with the known 1:1 ethene:water complex, which subsequently disappear on further increase in ethene concentration. At high concentrations of ethene, new features are observed at 3669 and 3585 cm(-1), which are red-shifted with respect to matrix-isolated nu(3) and nu(1) O-H stretching modes of water and the 1:1 ethene:water complex. These shifts are consistent with a pi...H interaction of a 2:1 ethene:water complex of the form (C(2)H(4)...H-O-H...C(2)H(4)). The analogous (C(2)D(4))(2)H(2)O complex shows little shifting from positions associated with (C(2)H(4))(2)H(2)O, while the (C(2)H(4))(2)D(2)O isotopomer shows large shifts to 2722.3 and 2617.2 cm(-1), having identical nu(3)(H(2)O)/nu(3)(D(2)O) and nu(1)(H(2)O)/nu(1)(D(2)O) values when compared with monomeric water isotopomers. Features at 3626.1 and 2666.2 cm(-1) are also observed and are attributed to (C(2)H(4))(2)HDO. DFT calculations at the B3LYP/6-311+G(d,p) level for each isotopomer are presented, and the predicted vibrational frequencies are directly compared with experimental values. The interaction energy for the formation of the 2:1 ethene:water complex from the 1:1 ethene:water complex is also presented.     

Contribution to the analysis of the predissociated rovibronic structure of the symmetric isotopomers 16O3 and 18O3 of ozone near 10,400 cm-1): [3A2(3(2)(0)) <-- X1A1(0(0)(0))] and 3B2 <-- X1A1

The absorption spectrum of ozone was recorded at low temperatures (down to -135 degrees C) by high resolution Fourier transform spectrometry and intra cavity laser absorption spectroscopy (ICLAS) near 10,400 cm-1. A preliminary analysis of the rotational structure of the absorption spectra of 16O3 and 18O3 shows that this spectral region corresponds to a superposition of two different electronic transitions, one with a very broad rotational structure, showing for the first time the asymmetric stretching frequency mode nu3 of the electronic state 3A2, the other formed by a completely diffuse band, probably the 2(1)(0) band of a new transition due to the triplet electronic state 3B2. Predissociation effects induce large broadening of the rotational lines for the transition centered at 10,473 cm-1 identified as the 3(2)(0) band of the 3A2 <-- X1A1 electronic transition. The rotational structure cannot be analyzed directly but instead the band contour method was used to confirm the symmetry of the transition and to estimate the spectroscopic constants for the 16O isotopomer. The origin of the band is at 10,473 +/- 3 cm-1 and the value of the 16O3(3A2) antisymmetric stretching frequency mode is equal to 460 +/- 2 cm-1. We believe that the diffuse band is due to the 3B2 state and is located at about 10,363 +/- 3 cm-1 for 16O3 and 10,354 +/- 3 cm-1 for 18O3. The isotopic rules confirm the different results obtained for 18O3 and 16O3.     

Absolute line intensities for formic acid and dissociation constant of the dimer

Absolute line intensities in the nu(6) and nu(8) interacting bands of trans-HCOOH, observed near 1105.4 and 1033.5 cm(-1), respectively, and the dissociation constant of the formic acid dimer (HCOOH)(2) have been measured using Fourier transform spectroscopy at a resolution of 0.002 cm(-1). Eleven spectra of formic acid, at 296.0(5) K and pressures ranging from 14.28(25) to 314.0(24) Pa, have been recorded between 600 and 1900 cm(-1) with an absorption path length of 19.7(2) cm. 437 integrated absorption coefficients have been measured for 72 lines in the nu(6) band. Analysis of the pressure dependence yielded the dissociation constant of the formic acid dimer, K(p)=361(45) Pa, and the absolute intensity of the 72 lines of HCOOH. The accuracy of these results was carefully estimated. The absolute intensities of four lines of the weak nu(8) band were also measured. Using an appropriate theory, the integrated intensity of the nu(6) and nu(8) bands was determined to be 3.47 x 10(-17) and 4.68 x 10(-19) cm(-1)(molecule cm(-2)) respectively, at 296 K. Both the dissociation constant and integrated intensities were compared to earlier measurements.     

Observation and rovibrational analysis of the intermolecular NH3 libration band nu9(1) of H3N-HCN

The high-resolution far-infrared absorption spectrum of the gaseous molecular complex H(3)N-HCN is recorded by means of static gas-phase Fourier transform far-infrared spectroscopy at 247 K, using a synchrotron radiation source. The spectrum contains distinct rotational structures which are assigned to the intermolecular NH(3) libration band nu9(1) (nu(B)) of the pyramidal H(3)N-HCN complex. A rovibrational analysis based on a standard semirigid symmetric top molecule model yields the band origin of 260.03(10) cm(-1), together with values for the upper state rotational constant B' and the upper state quartic centrifugal distortion constants D'(J) and D'(JK). The values for the upper state spectroscopic constants indicate that the hydrogen bond in the H(3)N-HCN complex is destabilized by 5% and elongates by 0.010 A upon excitation of a quantum of libration of the hydrogen bond acceptor molecule.     

Diode laser spectroscopy of the nu(8) band of the SF(5)Cl molecule

Diode laser spectra of SF(5)Cl have been recorded in the nu(8) band region at a temperature of ca. 240 K, a pressure of 0.25 mbar and an instrumental bandwidth of ca. 0.001 cm(-1). Four regions have been studied: a first one in the P-branch (906.849-907.687 cm(-1)), a second one in the Q-branch (910.407-910.944 cm(-1)), and two other ones in the R-branch (913.957-914.556 and 917.853-918.705 cm(-1) ). The whole nu(1)/nu(8) dyad of SF(5)35Cl has been previously recorded in the group of Professor H. Burger in Wuppertal, thanks to a Fourier transform infrared spectrometer. These data have thus been combined with our diode laser ones in the aim of refining the analysis. We used an effective Hamiltonian developed up to the fourth order and a set of programs called C(4nu)TDS. One thousand three hundred and forty-six transitions for nu(1), 495 (FTIR: 351; diode laser: 144) transitions for nu(8), and 406 ground state combination differences have been assigned and fitted. A global fit has been obtained with a rms of 0.00081 cm(-1) for the nu(1) band, 0.0012 cm(-1) for the FTIR data of the nu(8) band, 0.00055 cm(-1) for the diode laser data of this same band, and 0.00064 cm(-1) for the ground state. It appears that more data (for instance, using a supersonic jet) are still necessary to obtain a completely satisfactory analysis of the nu(8) region.     

The visible absorption spectrum of OBrO, investigated by Fourier transform spectroscopy

By the utilization of a new laboratory method to synthesize OBrO employing an electric discharge, the visible absorption spectrum of gaseous OBrO has been investigated. Absorption spectra of OBrO have been recorded at 298 K, using a continuous-scan Fourier transform spectrometer at a spectral resolution of 0.8 cm(-1). A detailed vibrational and rotational analysis of the observed transitions has been carried out. The FTS measurements provide experimental evidence that the visible absorption spectrum of OBrO results from the electronic transition C(2A2)-X(2B1). Vibrational constants have been determined for the C(2A2) state (omega(1) = 648.3 +/- 1.9 cm(-1) and omega 2 = 212.8 +/- 1.2 cm(-1)) and for the X(2B1) state (omega 1 = 804.1 +/- 0.8 cm(-1) and omega 2 = 312.2 +/- 0.5 cm(-1)). The vibrational bands (1,0,0), (2,0,0), and (1,1,0) show rotational structure, whereas the other observed bands are unstructured because of strong predissociation. Rotational constants have been determined experimentally for the upper electronic state C(2A2). By modeling the band contours, predissociation lifetimes have been estimated. Further, an estimate for the absorption cross-section of OBrO has been made by assessing the bromine budget within the gas mixture, and atmospheric lifetimes of OBrO have been calculated using a photochemical model.     

Wide temperature range (T = 295 K and 770-1305 K) study of the kinetics of the reactions HCO + NO and HCO + NO2 using frequency modulation spectroscopy

The rate constants for , HCO + NO --> HNO + CO, and , HCO + NO(2)--> products, have been measured at temperatures between 770 K < T < 1305 K behind reflected shock waves and, for the purpose of a consistency check, in a slow flow reactor at room temperature. HCO radicals were generated by 193 nm excimer laser photolysis of diluted gas mixtures containing glyoxal, (CHO)(2), and NO or NO(2) in argon and were monitored using frequency modulation (FM) absorption spectroscopy. Kinetic simulations based on a comprehensive reaction mechanism showed that the rate constants for the title reactions could be sensitively extracted from the measured HCO profiles. The determined high temperature rate constants are k(1)(769-1307 K) = (7.1 +/- 2.7) x 10(12) cm(3) mol(-1) s(-1) and k(2)(804-1186 K) = (3.3 +/- 1.8) x 10(13) cm(3) mol(-1) s(-1). The room temperature values were found to be in very good agreement with existing literature data and show that both reactions are essentially temperature independent. The weak temperature dependence of can be explained by the interplay of a dominating direct abstraction pathway and a complex-forming mechanism. Both pathways yield the products HNO + CO. In contrast to , no evidence for a significant contribution of a direct high temperature abstraction channel was found for . Here, the observed temperature independent overall rate constant can be described by a complex-forming mechanism with several product channels. Detailed information on the strongly temperature dependent channel branching ratios is provided. Moreover, the high temperature rate constant of , OH + (CHO)(2), has been determined to be k(7) approximately 1.1 x 10(13) cm(3) mol(-1) s(-1).     

Infrared diode laser spectroscopy of the deltanu=2 band of AlF

A vibrational-rotational spectrum of the deltanu=2 transitions of a high-temperature molecule AlF was observed between 1,490 and 1,586 cm(-1) with a diode laser spectrometer. Measurements were made on the nu=3-1, 4-2, 5-3 and 8-6 bands at a temperature of 900 degrees C. Measured spectral lines were fitted to effective band constants nu(0), B(nu) and D(nu) for each band. Present measurements were made with only one Pb-salt laser diode. Physical significance of the effective band constants is discussed.     

Study of the H-F stretching band in the absorption spectrum of (CH3)2O...HF in the gas phase

The absorption spectra of the (CH3)2O...HF complex in the range of 4200-2800 cm(-1) were recorded in the gas phase at a resolutions of 0.1 cm(-1) at T = 190-340 K. The spectra obtained were used to analyze their structure and to determine the temperature dependencies of the first and second spectral moments. The band shape of the (CH3)2O...HF complex in the region of the nu1(HF) stretching mode was reconstructed nonempirically. The nu1 and nu3 stretching vibrations and four bending vibrations responsible for the formation of the band shape were considered. The equilibrium geometry and the 1D-4D potential energy surfaces were calculated at the MP2 6-311++G(2d,2p) level with the basis set superposition error taken into account. On the basis of these surfaces, a number of one- and multidimensional anharmonic vibrational problems were solved by the variational method. Solutions of auxiliary 1D and 2D vibrational problems showed the strong coupling between the modes. The energy levels, transition frequencies and intensities, and the rotational constants for the combining vibrational states necessary to reconstruct the spectrum were obtained from solutions of the 4D problem (nu1, nu3, nu5(B2), nu6(B2)) and the 2D problem (nu5(B1), nu6(B1)). The theoretical spectra reconstructed for different temperatures as a superposition of rovibrational bands associated with the fundamental, hot, sum, and difference transitions reproduce the shape and separate spectral features of the experimental spectra. The calculated value of the nu1 frequency is 3424 cm(-1). Along with the frequencies and absolute intensities, the calculation yields the vibrationally averaged values of the separation between the centers of mass of the monomers Rc.-of-m., R(O...F), and r(HF) for different states. In particular, upon excitation of the nu1 mode, Rc.-of-m. becomes shorter by 0.0861 A, and r(HF) becomes longer by 0.0474 A.     

Raman spectroscopy of uranyl rare earth carbonate kamotoite-(Y)

Raman spectroscopy at 298 and 77K has been used to study the mineral kamotoite-(Y), a uranyl rare earth carbonate mineral of formula Y(2)(UO(2))(4)(CO(3))(3)(OH)(8).10-11H(2)O. The mineral is characterised by two Raman bands at 1130.9 and 1124.6 cm(-1) assigned to the nu(1) symmetric stretching mode of the (CO(3))(2-) units, while those at 1170.4 and 862.3 cm(-1) (77K) to the deltaU-OH bending vibrations. The assignment of the two bands at 814.7 and 809.6 cm(-1) is difficult because of the potential overlap between the symmetric stretching modes of the (UO(2))(2+) units and the nu(2) bending modes of the (CO(3))(2-) units. Only a single band is observed in the 77K spectrum at 811.6 cm(-1). One possible assignment is that the band at 814.7 cm(-1) is attributable to the nu(1) symmetric stretching mode of the (UO(2))(2+) units and the second band at 809.6 cm(-1) is due to the nu(2) bending modes of the (CO(3))(2-) units. Bands observed at 584 and 547.3 cm(-1) are attributed to water librational modes. An intense band at 417.7 cm(-1) resolved into two components at 422.0 and 416.6 cm(-1) in the 77K spectrum is assigned to an Y(2)O(2) stretching vibration. Bands at 336.3, 286.4 and 231.6 cm(-1) are assigned to the nu(2) (UO(2))(2+) bending modes. U-O bond lengths in uranyl are calculated from the wavenumbers of the uranyl symmetric stretching vibrations. The presence of symmetrically distinct uranyl and carbonate units in the crystal structure of kamotoite-(Y) is assumed. Hydrogen-bonding network related to the presence of water molecules and hydroxyls is shortly discussed.     

Infrared laser spectroscopy of jet-cooled carbon clusters: the nu 5 band of linear C9

The nu 5 antisymmetric stretching vibration of 1 sigma+g C9 has been observed using direct infrared diode laser absorption spectroscopy of a pulsed supersonic cluster beam. Twenty-eight rovibrational transitions measured in the region of 2079-2081 cm-1 were assigned to this band. A combined least squares fit of these transitions with previously reported nu 6 transitions yielded the following molecular constants for the nu 5 band: nu 0 = 2 079.673 58(17) cm-1, B"= 0.014 321 4(10) cm-1, and B'=0.014 288 9(10) cm-1. The IR intensity of the nu 5 band relative to nu 6 was found to be 0.108 +/- 0.006. Theoretical predictions for the relative intensities vary widely depending upon the level of theory employed, and the experimental value reported here is in reasonable agreement only with the result obtained from the most sophisticated ab initio calculation considered (CCSD).     

Anharmonic vibrational frequencies and vibrationally averaged structures and nuclear magnetic resonance parameters of FHF-

The anharmonic vibrational frequencies of FHF(-) were computed by the vibrational self-consistent-field, configuration-interaction, and second-order perturbation methods with a multiresolution composite potential energy surface generated by the electronic coupled-cluster method with various basis sets. Anharmonic vibrational averaging was performed for the bond length and nuclear magnetic resonance indirect spin-spin coupling constants, where the latter computed by the equation-of-motion coupled-cluster method. The calculations placed the vibrational frequencies at 580 (nu(1)), 1292 (nu(2)), 1313 (nu(3)), 1837 (nu(1) + nu(3)), and 1864 cm(-1) (nu(1) + nu(2)), the zero-point H-F bond length (r(0)) at 1.1539 A, the zero-point one-bond spin-spin coupling constant [(1)J(0)(HF)] at 124 Hz, and the bond dissociation energy (D(0)) at 43.3 kcal/mol. They agreed excellently with the corresponding experimental values: nu(1) = 583 cm(-1), nu(2) = 1286 cm(-1), nu(3) = 1331 cm(-1), nu(1) + nu(3) = 1849 cm(-1), nu(1) + nu(2) = 1858 cm(-1), r(0) = 1.1522 A, (1)J(0)(HF) = 124+/-3 Hz, and D(0) = 44.4+/-1.6 kcal/mol. The vibrationally averaged bond lengths matched closely the experimental values of five excited vibrational states, furnishing a highly dependable basis for correct band assignments. An adiabatic separation of high- (nu(3)) and low-frequency (nu(1)) stretching modes was examined and found to explain semiquantitatively the appearance of a nu(1) progression on nu(3). Our calculations predicted a value of 186 Hz for experimentally inaccessible (2)J(0)(FF).     

Infrared and infrared emission spectroscopy of the zinc carbonate mineral smithsonite

Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440cm(-1) is assigned to the nu(3) CO(3)(2-) antisymmetric stretching vibration. An additional band is resolved at 1335cm(-1). An intense sharp Raman band at 1092cm(-1) is assigned to the CO(3)(2-) symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442cm(-1) shifting to lower wavenumbers with thermal treatment. A band observed at 870cm(-1) with a band of lesser intensity at 842cm(-1) shifts to higher wavenumbers upon thermal treatment and is observed at 865cm(-1) at 400 degrees C and is assigned to the CO(3)(2-)nu(2) mode. No nu(2) bending modes are observed in the Raman spectra for smithsonite. The band at 746cm(-1) shifts to 743cm(-1) at 400 degrees C and is attributed to the CO(3)(2-)nu(4) in phase bending modes. Two infrared bands at 744 and around 729cm(-1) are assigned to the nu(4) in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO(6) octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991cm(-1) in both the IE and infrared spectra are attributed to combination bands.     

Jet-cooled diode laser spectra of CF3Br in the 9.2 microm region and rovibrational analysis of symmetric CF3 stretching mode

Pulsed slit-jet high resolution (up to 0.0009 cm(-1) FWHM) infrared diode laser spectra of CF(3)Br, with natural isotopic abundance, were obtained in the region around 9.2 microm at the rotational temperature of about 50 K. In addition, diode laser spectra at reduced temperature (200 K) were recorded. We present here the rovibrational analysis of the nu(1) fundamental in the range 1075-1090 cm(-1). The fine structure of many P(J) and R(J) clusters has been well resolved for the first time. The assignment of rovibrational transitions has been accomplished up to K = 27, J = 63 for CFBr and K = 33, J = 62 for CFBr. A total of 636 (CFBr) and 880 (CFBr) lines were used in the final fit and a very accurate set of molecular constants, including the quartic centrifugal distortion coefficients for the v(1) = 1 state of both the bromine isotopologues, was obtained. In addition, spectral features belonging to the nu(1) + nu(6)-nu(6) hot band were unambiguously identified and a set of spectroscopic parameters were determined.