Theoretical study on the vibrational structure of S0 thiophosgene from the origin to dissociation

In this work, using our vibrational variational calculation method and a recently derived refined quartic potential energy surface for S₀ thiophosgene, we have carried out large scale vibrational calculations to analyze the vibrational structure of this electronic state in the whole range of vibrational excitation energies down from the origin and up to the dissociation limit (at ↼20,000 cm^↙1). In the lower excited vibrational range we have achieved satisfactory coincidence of calculated to experimentally measured frequencies, while at the higher vibrational excitations our main objective has been to estimate what part of the available vibrational level density is effectively involved into the vibrational mixing and IVR. The results from our calculations have been compared to the available experimentally obtained dataset (obtained from synchrotron IR, SEP and LIF spectra) as well as to conclusions from the analyses by other authors using local coupling models.     

FTIR and millimeter wave investigation of the 7 and 9 states of formic acid HCOOH and HCOOH

High resolution FTIR spectra of the two overlapping bands ν₇ and ν₉ of the ¹³C species of formic acid have been measured and analyzed. Rotational transitions in the millimeter wave region were measured and included in the analysis. As in the parent species, there is a strong Coriolis interaction between the 7¹ and 9¹ states. The corresponding IR bands of the parent species have been remeasured and new MMW transitions recorded. The analysis of the spectra for the two species provides an opportunity to consider a reduction of the Hamiltonian employed for the analysis of this type of interacting system of states. Parameters with low correlations could be obtained. Several interstellar features coincide with transitions predicted from these parameters.     

Fluorinated copolymers and terpolymers based on vinylidene fluoride and bearing sulfonic acid side‐group

The radical co‐ and terpolymerization of perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride (PFSVE) with 1,1‐difluoroethylene (or vinylidene fluoride, VDF or VF₂), hexafluoropropene (HFP), chlorotrifluoroethylene (CTFE), and bromotrifluoroethylene (BrTFE) is presented. Although PFSVE could not homopolymerize under radical initiation, it could be copolymerized in solution under a radical initiator with VDF, while its copolymerizations with HFP or CTFE led to oligomers in low yields. The terpolymerizations of PFSVE with VDF and HFP, with VDF and CTFE, or with VDF and BrTFE also led to original fluorinated terpolymers bearing sulfonyl fluoride side‐groups. The conditions of co‐ and terpolymerization were optimized in terms of the nature and the amount of the radical initiators, of the nature of solvents (fluorinated or nonhalogenated), and of the initial amounts of fluorinated comonomers. The different mol % contents of comonomers in the co‐ and terpolymers were assessed by ¹⁹F NMR spectroscopy. A wide range of co‐ and terpolymers containing mol % of PFSVE functional monomer ranging from 10 to 70% was produced. The kinetics of copolymerization of VDF with PFSVE enabled to assess the reactivity ratios of both comonomers: r_VDF = 0.57 ± 0.15 and r_PFSVE = 0.07 ± 0.04 at 120 °C. The thermal and physicochemical properties were also studied. Moreover, the glass transition temperatures (T_gs) of poly(VDF‐co‐PFSVE) copolymers containing different amounts of VDF and PFSVE were determined and the theoretical T_g of poly(PFSVE) homopolymer was deduced. Then, the hydrolysis of the ? SO₂F into ? SO₃H function was investigated and enabled the synthesis of fluorinated copolymers bearing sulfonic acid functions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1814–1834, 2007     

α方石英振动光谱的计算

在价力场模型和已公布的α方石英喇曼光谱和红外光谱不完全的观测数据基础上，计算了α方石英振动光谱横模的全部基频和简正模式。基频的计算值和观测值符合较好。预言了至今尚未观测到的对称类Ａ２、Ｂ１各两个基频和Ｂ２的５个基频的位置。给出了α方石英的一组１０个力常数     

Temperature-dependent infrared spectra of torsional vibrations in acetic acid

The mid-IR and near-IR vapor phase spectrum of CH₃COOH was examined with a focus on the regions of the ν₁₇ O-H torsion and the ν₁ O-H stretch. Each region showed a number of peaks that were assigned using previous ab initio work, their temperature dependence, and analysis of the deuterated species of acetic acid (CD₃COOH, CH₃COOD, and CD₃COOD). These assignments correct and improve upon the values currently used in the literature. Many of the peaks were assigned as hot bands associated with either the ν₁₇ O-H torsion or the ν₁ O-H stretch. In addition, the first definitive assignment of the Q-branch of the ν₁ O-H stretch was made. The hot bands were shown to contribute a significant amount of absorption intensity to the ν₁ region at 298 K. An empirical temperature-dependent correction to the total absorption of the ν₁ O-H stretching region as well as an adjusted absolute cross-section for ν₁ are given and suggested for future use.     

The 5νNH and 5νND vibrational bands of partially deuterated ammonia species

Absorption spectra of gaseous samples containing NH₂D and NHD₂ have been measured in the 11 580-11 880 and 15 280-15 610 cm⁻¹ regions, corresponding to the 5ν_ND and 5ν_NH vibrational bands, respectively. Photoacoustic spectroscopy has been utilized for the measurement. The molecular constants of NH₂D in the 5ν_ND state and NHD₂ in the 5ν_NH state have been determined from the analysis of the obtained absorption spectrum. From the comparison of the constants with those of the vibrational ground states, structural changes caused by the stretching excitations have been elucidated. The HND bond angles are decreased by these excitations. The dependence of the molecular constants on the stretching quantum number has also been derived by simple Birge-Sponer and Dunham analyses.     

分子振动计算机模拟

我们用Ｃ语言开发出用于显示分子图形及振动的Ｍｏｌｆｉｇ软件，并为程序配备了多种功能和一个友好的人机交互界面以方便使用。经试用表明，该软件可为我们加强理解分子的振动光谱与结构之间的关系提供了有效的帮助。     

Buckling analysis of non-prismatic columns based on modified vibration modes

In this paper, a new procedure is formulated for the buckling analysis of tapered column members. The calculation of the buckling loads was carried out by using modified vibrational mode shape (MVM) and energy method. The change of stiffness within a column is characterized by introducing a tapering index. It is shown that, the changes in the vibrational mode shapes of a tapered column can be represented by considering a linear combination of various modes of uniform-section columns. As a result, by making use of these modified mode shapes (MVM) and applying the principle of stationary total potential energy, the buckling load of tapered columns can be obtained. Several numerical examples on tapered columns demonstrate the accuracy and efficiency of the proposed analytical method.     

Effect of the nature of mendiaxon–X interactions (X= Na, Cu, H) and the hydrogen bonding on the ν(C=O) behavior: theoretical and spectroscopic study

Theoretical and spectroscopic (IR and Raman) study of different 7-hydroxy-4-methylcoumarin (mendiaxon) systems (mend⁻, mendNa, mendCu, mendH and mendH · 2H₂O) were performed at B3LYP/6-31G(d) and B3LYP/6-31++G(d,p) levels of theory. The geometric and electronic structures as well as the vibrational behavior of the systems studied were discussed: (1) as to the changes that occurred in the anion coumarin ring upon the mend⁻–X⁺ (X⁺ =Na⁺, Cu⁺, H⁺) interactions and (2) as to the changes that occurred in mendH due to hydrogen bondings in mendH · 2H₂O. The largest bond length changes in the anion coumarin ring were obtained for mendH and the smallest ones for mendNa. The bond length changes were mainly produced from the electrostatic effect of the positive charge of X. The induced polarization of the C=O bond upon the mend⁻–X⁺ interactions was found to be opposite to the basic one and it led to shorter C=O bond lengths (higher ν(C=O) frequencies) in the order: mendNa, mendCu and mendH. Conversely, upon the hydrogen bonding the induced polarization of the C=O bond was found in the same direction as the basic one and it produced elongation to the C=O bond length (lower ν(C=O) frequency). On the basis of the correlations found, the ν(C=O) positions in mendNa, mendCu, mendH and mendH · 2H₂O were explained.     

New ground state constants of CH3Cl and CH3Cl from global polyad analysis

A global analysis of the infrared spectrum of chloromethane involving the ground state and the 13 vibrational states lying up to 2600 cm⁻¹ was recently achieved using high resolution Fourier transform spectra of pure isotopomers. More than 20 000 transitions (cold and hot bands) for each isotopomer ¹²CH₃³⁵Cl and ¹²CH₃³⁷Cl have been assigned and fitted with a standard deviation of about 3 × 10⁻⁴ cm⁻¹ close to the experimental precison. As part of this global effort, improved ground state constants up to sextic centrifugal distortion terms have been determined for each isotopomer taking advantage of the numerous allowed and perturtation-allowed transitions simultaneously fitted using our global model. The axial constants could be determined from ΔK ≠ 0 combinations arising from rovibrational local resonances within Polyads 3 and 5.