摘要:

The infrared spectrum of the perpendicular fundamentalv5of chloroform around 776 cm−1has been studied by applying two high resolution methods. A short range from the central part of the spectrum was measured with a diode laser by using a cold jet sample including chloroform in natural isotopic abundancies. More than 100 rotational lines of12CH35Cl3could be assigned. The whole band region was measured by a Fourier transform spectrometer at a resolution of 0.0010cm−1. In this case an isotopically pure sample of12CH35Cl3was used. Starting from the results of the diode laser investigation more than 2000 lines could be assigned with Jmax= 91 and Kmax= 58. In addition to the infrared spectra, millimetre-wave lines also were measured. A total of 58 lines corresponding toJvalues 22, 23 and 35 at the excited vibration state v5= 1 were assigned and analysed. All the data from three different spectra were simultaneously fitted and, for example, the results v0= 775.961 50(3) cm−1, 98,B5-B0= −0.180171(22) × 10−3cm−1, C5− C0= −0.170 57(15) × 10−3cm−1, and(Cζ)5= 0.047 5294(11) cm−1were obtained.

ISSN:0026-8976    

DOI:10.1080/00268970009483321

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The orientational data of four rigid solutes dissolved in the nematic solvents ZLI1132, EBBA and in a 55wt% ZLI1132 + EBBA mixture have been obtained from proton NMR spectra at different temperatures and used to find a relationship between the solute order in the two nematics and in their mixture. A crossed comparison of the data shows that a simple linear relation, where the normalized weights of the combination are coincident with the molar fractions of ZLI1132 and EBBA in the mixture, gives excellent agreement independently of the solutes and temperatures. Consideration is given to the possibility of a generalization of the results to any mixture of two nematics.

ISSN:0026-8976    

DOI:10.1080/00268970009483322

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The vibrational dynamics of thep-rert-butylcalix[8]arene and the 1:1 inclusion complex C60@p-tert-butylcalix[8]arene are investigated by a combination of inelastic neutron scattering (INS) and MM3 molecular mechanics calculations. The results show that the isolated, single molecule approximation breaks down and is not sufficient to explain the features observed experimentally. The origin of the line broadening in the low energy region is discussed in terms of intermolecular interactions: this effect is sharper in the case of the complex with the C60molecule, due to the high number of co-conformers allowed by the mismatch between the circumferences of the host and the guest. The successful interpretation of the INS spectra validates the use of the model adopted.

ISSN:0026-8976    

DOI:10.1080/00268970009483323

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Density expansion theories are often used, within the density functional formalism, to approximate the Helmholtz free-energy functional of simple classical fluids. An overview of the theoretical framework of density expansion theories is presented. Several density functional theories that employ truncated density expansions are then analysed with attention focused on their thermodynamic properties. It is found that, of these theories, only the commonly used mean-field theory satisfies the Gibbs adsorption equation; the inconsistencies within the other theories arise from truncation of the density expansion without appropriate modification of the expansion coefficients. Other repercussions of truncating the density expansion are discussed.

ISSN:0026-8976    

DOI:10.1080/00268970009483324

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The Fourier transform infrared spectrum of thev11band of ethylene-d4(C2D4) has been recorded with an unapodized resolution of 0.006 cm−1in the frequency range 2150 to 2250cm−1. Thev11band, with a band centre of about 2201 cm−1, was found to be perturbed by the nearbyv2+ v7band centred at about 2235 cm−1by a b-type Coriolis interaction. By fitting a total of 772 infrared transitions ofv11using a Watson's A-reduced Hamiltonian in the Irrepresentation with the inclusion of b-type Coriolis interaction term, two sets of constants, up to quartic distortion constants for thev11= 1 state, and principal rotational constants for thev2+ v7= 1 dark state, were derived. The inertia defect of thev11state was found to be 0.0693 ± 0.0004u Å2.

ISSN:0026-8976    

DOI:10.1080/00268970009483325

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The pure rotational spectrum of the near-spherical oblate symmetric top AsD3has been recorded in the 20–120cm−′ region with a resolution of 2.3 × 10−3m−1employing an FT interferometer. Rotational transitions with 5 ⩽J⩽ 29 and 0 ⩽ X ⩽ 25 of the ground state (GS) and thev2= 1 andv4= 1 excited states have been assigned. Splittings were observed for the GS, 98,K= 3 and 6 levels, theK= 3 levels ofv2and thekl= −2, 1, 4 and 7 levels ofv4.Furthermore thex,yCoriolis coupledv2andv4bands,v02= 654.4149cm−1, andv04= 714.3399 cm−1, have been examined with a resolution of 2.4 × 10−3cm−1, andca.2500 allowed and 336 ‘forbidden’ lines with J′max= 31 and K′max= 28 have been assigned. Appropriately weighted GS data comprising FIR lines, allowed and ‘forbidden’ (up to ΔK = ±6) GS combination differences, mmw data, and ΔJ = 0, ΔK = ±1 distortion moment transitions were fitted together, and GS parameters complete throughHparameters have been determined. Two different reductions of the Hamiltonian, either with ΔK = ±6 (h3) or ΔK = ±3 (ε) off-diagonal elements, have been employed. Equivalence of these reductions up toJ= 22 was established while forJ> 22 the ε reduction is superior. Thev2andv4data have been fitted with two equivalent models based on different reductions of the rovibrational Hamiltonian. In addition to the dominatingx,yCoriolis resonance, ζy240.520, Δ(k − l) = ±3 and ±6 interactions are important and were accounted for by the models. The transition moment ratio|M4: M2|=0.75 has been determined, with a positive sign of the productM2ζy24M4. An improved r0structure, r0(AsD) = 1.51753 Å and α0(DAsD) = 92.000°, has been determined.

ISSN:0026-8976    

DOI:10.1080/00268970009483326

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A31P and13C NMR study of powder and single crystal samples of two phosphoenolpyruvate (PEP) compounds, the tris-ammonium salt monohydrate (NH4)3(PEP)·H2O (1), and the mono-ammonium-salt (NH4)(H2PEP) (2) is presented. The P chemical shielding tensors in 1 are measured by31P single crystal NMR on four minuscule samples and assigned without ambiguity by exploiting the orientation-dependent31P-31p dipolar splittings of the resonance lines. The orientation of the31P chemical shielding tensor is discussed in terms of the C2v— and C3-type distortions of the phosphate PO4-coordination sphere. From13C MAS NMR experiments with31P rotary resonance recoupling on polycrystalline powder samples the orientations of the31P chemical shielding tensors in 1 and 2 are obtained, for 1 in very good agreement with the31P single crystal NMR results. Only some of the orientational parameters of the three13C chemical shielding tensors in the PEP moiety of 1 could be derived from13C MAS NMR experiments with31P rotary resonance recoupling.

ISSN:0026-8976    

DOI:10.1080/00268970009483327

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Monte Carlo (MC) simulation data for additive binary hard sphere mixtures are reported for dilute concentrations of the large sphere. Using a single occupancy linked cell method, binary hard sphere solutions with a size ratio of 5 are simulated at high reduced density and low concentration of the large sphere. Data for the solute-solvent pair distribution function show that at the lowest concentrations of the large sphere simulated, the Boublik-Mansoori-Carnahan-Starling-Leland (BMCSL) equation underestimates the contact value; whereas the recently proposed Henderson-Chan (HC) equation gives a good prediction. For the solute-solute contact value at the colloidal limit, the MC data lie between the two predictions. The BMCSL equation underestimates, while the HC equation overestimates, the correct solute-solute contact value.

ISSN:0026-8976    

DOI:10.1080/00268970009483328

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor