CRYSTAL-STRUCTURE AND INFRARED-SPECTRA OF A LANTHANUM COORDINATION COMPOUND WITH GLYCINE, ([LA(GLY)S-CENTER-DOT-2H2O]CENTER-DOT(CLO4)3)N

A lanthanum coordination compound with glycine {[La(Gly)3.2H2O].(ClO4)3}n (Gly = NH+ 3-CH2-COO-) was synthesized and obtained in the form of single crystals. Its X-ray crystal structure has been determined and the IR spectrum has been studied. Crystallo

INFRARED-SPECTRA OF DIMETHYLPHOSPHATE LANTHANIDE COMPLEXES

The infrared spectra of the crystalline solid samples of rare earth(III) dimethylphosphates Ln(DMP)3 (Ln = La, Ce, Nd) in the range 4000-100 cm-1 are discussed. It is shown that the spectra may be treated by dividing Ln(DMP)3 into two parts, an OP(OCH3)2O bridge and a LnO6 distortion octahedron. The absorption bands above 500 cm-1 may be clearly assigned. However, vibrational assignments in the far-infrared region are tentative.

INFRARED SPECTRA AND CRYSTAL STRUCTURE OF BIS-(DIMETHOXYLPHOSPHATO) COPPER

The title complex has beep synthesized by the reaction of CaCl2, with trimethyl phosphate. Its Infrared spectra from 4000 to 100 cm(-1) measured. The assignment of acme absorption bands was discussed. It is found that the stretching vibrations of bridge groups O-P-O are divided into two groups according to their bond length. The crystal structure of the complex boa been determined from single crystal K-ray diffraction data. The crystals belong to monoclinic system, space group P2(1)/c with cell parameteras, a = 1,0704(4), b = 0.5093(2), c = 1.9737(6)nm, beta = 96.23(3)degrees, V = 1.0696(6)nm(2), Z = 4, final R = 0.044. Copper ion is coordinated to five Rimester oxygen atoms to form a distorted square pyramid. The adjacent copper ions are connected by symmetric and non-symmetric bridge groups of O-P-O, forming an infinite one-dimensional chain coordination polymer.

THERMAL ANALYSIS AND INFRARED SPECTRA OF DIALKYLAMMONIUM TETRAC HLOROCUPRATE

The thermal stability and the solid solid phase transitions in Ills compounds with n = 7-12 have been studied by DSC and TG methods. Comparision with CnZn compounds want made. The nature of three phases of CnCu has been discussed in terms of infrared spectroscopy and the assignment of the phase transitions has been given. The thermal stability of CnCu is lower than that of CnZn and presents an obvious odd even effect. All of these compounds exhibit two solid solid phase transitions in the temperature range of 248-337 K. The peak tempe nature of phase transitions changes regularly. The peak temperature or the main phase transition increases with the chain length. The total transition enthalpies and entropies increase with increasing chain length. When n <= 9, the high temperature phase exists in a partial disorder state. When n >= 10, the high temperature phase exists in a conformational disorder state. The main phase transition and the phase transition at 307.7 K of CnCu may mainly are from the change of the packing structure and the change of the partial conformational order-disorder of alkyl chain, respectively.

Infrared spectra of C2H2 under jet-cooled and para-H2 matrix conditions

In spectra of jet-cooled C2H2 recorded with an FTIR spectrometer, the ν5, ν4 + ν5, ν3 and ν2 + ν4 + ν5 bands all exhibit an intensity distribution corresponding to ∼6 K for rotation, with no evidence of nuclear spin conversion. Spectra of C2H2 isolated in solid p-H2 show no evidence of rotation of C2H2. The strong interaction between ν3 and ν2 + ν4 + ν5 in the gas phase is diminished in solid p-H2. Lines associated with dimer, trimer and tetramer of C2H2 are identified. Spectral features characteristic of solid state acetylene are observed under jet-cooled conditions. © 2007 Elsevier B.V. All rights reserved.

Restricted rotation dynamics and far-infrared spectra of liquid water governed by elastic interactions

A semi-phenomenological model describing wideband dielectric and far-infrared spectra of liquid water was proposed recently by the same authors [J. Mol. Struct. 606 (2002) 9], where a small dipole-moment component changing harmonically with time determines a weak absorption band (termed here the R-band) centred at the wavenumber v similar to 200 cm(-1). In the present work, a rough molecular theory of the R-band based on the concept of elastic interactions is given. Stretching and bending of hydrogen bonds cause restricted rotation (RR) of a polar water molecule in terms of a dimer comprising the H- bonded molecules. Analytical expression for the RR frequency nu(str) is derived as a function of the RR amplitude, geometrical parameters and force constants. The density g(nu(str)) of frequency distribution is shown to be centred in the R-band. The spectrum of the dipolar auto-correlation function calculated for this structural-dynamical model is found. A composite model comprising two intermolecular potentials is proposed, which yields for water a good description of the experimental wideband (from 0 to 1000 cm(- 1)) spectra of complex permittivity and of absorption coefficient. The presented interpretation of these spectra is based on a concept that water presents a two-component solution, with components differing by the types of molecular rotation. (C) 2003 Elsevier B.V. All rights reserved.

Analytical calculation of far infrared spectra of ice in terms of a molecular model

Wideband far infrared (FIR) spectra of complex permittivity e(p) of ice are calculated in terms of a simple analytical theory based on the method of dipolar autocorrelation functions. The molecular model represents a revision of the model recently presented for liquid water in Adv. Chem. Phys. 127 (2003) 65. A composite two-fractional model is proposed. The model is characterised by three phenomenological potential wells corresponding to the three FIR bands observed in ice. The first fraction comprises dipoles reorienting in a rather narrow and deep hat-like well; these dipoles generate the librational band centred at the frequency approximate to 880 cm(-1). The second fraction comprises elastically interacting particles; they generate two nearby bands placed around frequency 200 cm(-1). For description of one of these bands the harmonic oscillator (HO) model is used, in which translational oscillations of two charged molecules along the H-bond are considered. The other band is produced by the H-bond stretch, which governs hindered rotation of a rigid dipole. Such a motion and its dielectric response are described in terms of a new cut parabolic (CP) model applicable for any vibration amplitude. The composite hat-HO-CP model results in a smooth epsilon(nu) ice spectrum, which does not resemble the noise-like spectra of ice met in the known literature. The proposed theory satisfactorily agrees with the experimental ice spectrum measured at - 7 degrees C. The calculated longitudinal optic-transverse optic (LO-TO) splitting occurring at approximate to 250 cm(-1) qualitatively agrees with the measured data. (c) 2004 Elsevier B.V. All rights reserved.

Specific and unspecific interactions in polar fluids in view of wideband dielectric far-infrared spectra

A simple molecular analytical theory of dielectric relaxation in strongly polar fluids is considered in terms of a semi- phenomenological approach. Theoretical spectra epsilon(v), a(v) of complex permittivity and absorption coefficient are fully determined by a form of intermolecular potential well, in which a dipole reorients. In a recent publication by VI. Gaiduk, O.F. Nielsen, and T.S. Perova [J. Molliq 95 (1002) 1-25] the wideband spectra of liquid H2O and D2O were described in terms of a composite model comprising the rectangular and the cosine squared potential wells. Much better results are achieved in this work, where the rectangular well is replaced by a well with a rounded bottom termed the hat-curved well. The spectrum of the auto-correlation function (ACF) is calculated for such a potential. The proposed theory of a composite model, comprising hat-curved and parabolic wells, is applied for liquid water. This model is capable for describing the Debye relaxation region, the second relaxation region in the submillimeter wavelength range, and the far infra-red (FIR) e(v), a(v) spectra, where an intense librational band and an additional weak band are placed, respectively, near 700 cm(-1) and 200 cm(-1). The latter band reflects the features of so-called specific (viz. directly related to H-bonds) interactions and the former band reflects the features of unspecific interactions. The physical mechanisms connected with these types of interactions are discussed in terms of two relevant types of water structure (types of molecular rotation). The proposed theory is also applied to a non-associated liquid in terms of one hat-curved potential well. (C) 2004 Elsevier B.V. All rights reserved.

The Type Ic SN 2007gr: a census of the ejecta from late-time optical-infrared spectra

Nebular spectra of supernovae (SNe) offer an unimpeded view of the inner region of the ejecta, where most nucleosynthesis takes place. Optical spectra cover most, but not all, of the emitting elements and therefore offer only a partial view of the products of the explosion. Simultaneous optical-infrared spectra, on the other hand, contain emission lines of all important elements, from C and O through to the intermediate mass elements (IME) Mg, Si, S, Ca and to Fe and Ni. In particular, Si and S are best seen in the IR. The availability of IR data makes it possible to explore in greater detail the results of the explosion. SN 2007gr is the first Type Ic SN for which such data are available. Modelling the spectra with a non-local thermodynamic equilibrium (NLTE) code reveals that the inner ejecta contain similar to 1M(circle dot) of material within a velocity of approximate to 4500 km s(-1). The same mass of Ni-56 derived from the light-curve peak (0.076M(circle dot)) was used to power the spectrum, yielding consistent results. Oxygen is the dominant element, contributing similar to 0.8M(circle dot). The C/O ratio is

Signatures of delayed detonation, asymmetry, and electron capture in the mid-infrared spectra of supernovae 2003hv and 2005df

We present mid-infrared (5.2-15.2 mu m) spectra of the Type Ia supernovae (SNe Ia) 2003hv and 2005df observed with the Spitzer Space Telescope. These are the first observed mid-infrared spectra of thermonuclear supernovae, and show strong emission from fine-structure lines of Ni, Co, S, and Ar. The detection of Ni emission in SN 2005df 135 days after the explosion provides direct observational evidence of high-density nuclear burning forming a significant amount of stable Ni in a SN Ia. The SN 2005df Ar lines also exhibit a two-pronged emission profile, implying that the Ar emission deviates significantly from spherical symmetry. The spectrum of SN 2003hv also shows signs of asymmetry, exhibiting blueshifted [Co (III)], which matches the blueshift of [Fe (II)] lines in nearly coeval near-infrared spectra. Finally, local thermodynamic equilibrium abundance estimates for the yield of radioactive Ni-56 give M-56Ni approximate to 0.5 M-circle dot, for SN 2003hv, but only M-56Ni approximate to 0.13-0.22 M-circle dot for the apparently subluminous SN 2005df, supporting the notion that the luminosity of SNe Ia is primarily a function of the radioactive 56Ni yield. The observed emission-line profiles in the SN 2005df spectrum indicate a chemically stratified ejecta structure, which matches the predictions of delayed detonation (DD) models, but is entirely incompatible with current three-dimensional deflagration models. Furthermore, the degree that this layering persists to the innermost regions of the supernova is difficult to explain even in a DD scenario, where the innermost ejecta are still the product of deflagration burning. Thus, while these results are roughly consistent with a delayed detonation, it is clear that a key piece of physics is still missing from our understanding of the earliest phases of SN Ia explosions.

Interpreting the near-infrared spectra of the 'golden standard' Type Ia supernova 2005cf

We present nine near-infrared (NIR) spectra of supernova (SN) 2005cf at epochs from -10 to +42d with respect to B-band maximum, complementing the existing excellent data sets available for this prototypical Type Ia SN at other wavelengths. The spectra show a time evolution and spectral features characteristic of normal Type Ia SNe, as illustrated by a comparison with SNe 1999ee, 2002bo and 2003du. The broad-band spectral energy distribution (SED) of SN 2005cf is studied in combined ultraviolet (UV), optical and NIR spectra at five epochs between ~8d before and ~10d after maximum light. We also present synthetic spectra of the hydrodynamic explosion model W7, which reproduce the key properties of SN 2005cf not only at UV-optical as previously reported, but also at NIR wavelengths. From the radiative-transfer calculations we infer that fluorescence is the driving mechanism that shapes the SED of SNe Ia. In particular, the NIR part of the spectrum is almost devoid of absorption features, and instead dominated by fluorescent emission of both iron-group material and intermediate-mass elements at pre-maximum epochs, and pure iron-group material after maximum light. A single P-Cygni feature of Mgii at early epochs and a series of relatively unblended Coii lines at late phases allow us to constrain the regions of the ejecta in which the respective elements are abundant. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Coriolis perturbations in the infrared spectrum of allene

High resolution infrared spectra of the ν9 and ν10 perpendicular fundamentals of the allene molecule are reported, in which the J structure in the sub-bands has been partially resolved. Analysis of the latter shows that the vibrational origin ν9 = 999 cm−1, some 35 cm−1 below previous assignments. The pronounced asymmetry in the intensity distribution of the rotational structure which this assignment implies is shown to be expected theoretically, due to the Coriolis perturbations involved, and it is interpreted in terms of the sign and magnitude of the ratio of the dipole moment derivatives in the two fundamentals. The results of this analysis are shown to be in good agreement with observations on allene-1.1-d2, where similar intensity perturbations are observed, and with an independent analysis of the ν8 band of allene-h4. The A rotational constant of allene-h4 is found to have the value 4.82 ± 0.01 cm−1, and for the molecular geometry we obtain r(CH) = 1.084 A, r(CC) = 1.308 A, and HCH = 118.4°. A partial analysis of the rotational structure of the hot bands (ν9 + ν11 − ν11) and (ν10 + ν11 − ν11) is presented; these provide an example of a strong Coriolis interaction between nearly degenerate A1A2 and B1B2 pairs of vibrational levels. Some localized rotational perturbations in the ν9 and ν10 fundamentals are also noted, and their possible interpretations are discussed.

Coriolis perturbations in the infrared spectrum of diborane

High‐resolution infrared spectra of B2H6 vapor are reported. The sample was prepared from the naturally occurring 11B☒10B isotopic mixture. The rotational structure of the infrared bands has been analysed for Coriolis perturbations due to rotation about the axis of least moment of inertia (the B⋅⋅⋅B axis). The following results have been obtained: (a) interaction between the Type A fundamental ν18 and the inactive fundamental ν5 has been observed, thus confirming the assignment of ν5 at 833 cm—1, giving ∣ ζ5,18Z ∣=0.55±0.05; (b) interaction observed between the Type A combination band (ν10+ν12) at 1283 cm—1 and the inactive combination (ν10+ν7) gives an estimate of the unobserved fundamental ν7 as 850±30 cm—1, and an estimate of ∣ ζ7,12Z ∣=0.6±0.1; (c) the absence of any observed perturbation of the Type C fundamental ν14 at 973 cm—1, suggests, by negative arguments, that either the unobserved fundamental ν9 does not lie in the frequency range 900 to 1100 cm—1, or ∣ ζ9,14Z ∣<0.2. The assignment of the unobserved fundamental vibrations of diborane is discussed in the light of this evidence.