Electronic structure and infrared spectrum of a W_n C^(0,±) (n = 1-6) cluster

WnC0＇± （n= 1-6） clusters are investigated by using the density functional theory （DFT） at the B3LYP/LANL2DZ level. We find that the neutral, anionic and cationic ground state structures are similar within the same size, and constituted by substituting a C atom for one W atom in the structures of Wn＋1 clusters. The natural bond orbital （NBO） charge analyses indicate that the direction of electron transfer is from the W atom to the 2p orbital of the C atom. In addition, the calculated infrared spectra of the WnC0＇± （n= 2-6） clusters manifest that the vibrational frequencies of neutral, anionic and cationic clusters are similar in a range of 80 cm-1-864 cm-1. The high frequency, strong peak modes are found to be an almost stretched deformation of the carbide atom. Finally, the polarizabilities of WnC0＇± （n= 1-6） clusters are also discussed.

Detection of Chlorpyrifos Residues in Akesu Red Fuji Apple based on Near Infrared Spectrum

[Objective] The paper was to explore a method for detecting chlorpyrifos residues in red Fuji apple. [Method] The original spectral data of apple samples sprayed with different volume fractions of chlorpyrifos were collected using near infrared spectrometer at the band of 4 000-10 000 cm^（-1）. The original spectra were pre-treated by a variety of methods, and partial least squares（PLS） model was established for predictive analysis. [Result] Near infrared spectrum showed sensitivity to apple samples sprayed with different volume fractions of chlorpyrifos, but had low precision on pesticide-free samples. Data of blank control group were further eliminated for modeling prediction. The results showed that the results were the best when pre-treated with first derivative（FD）： R=0.987 9; the square error of prediction（SEP） was 0.173 6; the root-mean-square error of cross-validation（RMSECV） was 0.120 5; and the precision was 0.923 4. [Conclusion] Near infrared spectrum can better predict chlorpyrifos residue, providing a new method for detecting chlorpyrifos residues in Akesu red Fuji apple.

Preparation of Ultrafine SiO2 Powder from Rice Husk and Properties of Its Infrared Spectrum

This paper discussed impact of temperature on the size distribution in preparing ultrafine silica from rice husk.The samples prepared were analyzed with infrared spectrum,and the relation between the particle size and intensity of characteristic absorption peak of IR at center around 1 100 cm-1 was disscussed with the baseline method.Results show that when the temperature is 650 ℃ and roasting time is 11 h,at optimal reaction conditions,the size distribution of the ultrafine silica powder prepared is relatively concentrated,and the average particle size is 199.5 nm.Moreover,the characteristic absorption band of IR is broadening gradually along with particle size decreasing.

Effects of Size and Microstructures on Infrared Spectra of Pyrolusites

Nanofibrous pyrolusite （β-MnO2） was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared （FTIR） spectra showed that A2u mode frequency shifts from 514 cm-1 to 574 cm-1 to 617 cm-1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long＋2 short and 4 short＋2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.

Infrared Spectroscopic and Theoretical Studies on Cobalt(Ⅱ) Complex of Maleinitriledithiolate and 4, 4′-Dimethyl-2, 2′-bipyridine

The complete experimental IR spectra and vibrational analysis of the title complex Co(mnt)(dmbpy) were reported in this paper. The results show that the complex molecule has a planar geometry belonging to point group C 2v and ground electronic state with spin quartet. A new method for analyzing vibrational spectra of complicated molecule is established. The essential of this method is to point out main fixed points and pivotal vibrational units in assignment for each fundamental band. Two new symbols η (heaving along the specified direction) and M (midpoint of a bond or unit) were defined for describing the vibrational modes accurately.

Nanosecond-time-resolved infrared spectroscopic study of fast relaxation kinetics of protein folding by means of laser-induced temperature-jump

Elucidating the initial kinetics of folding pathways is critical to the understanding of the protein folding mechanism. Transient infrared spectroscopy has proved a powerful tool to probe the folding kinetics. Herein we report the construction of a nanosecond laser-induced temperature-jump （T-jump） technique coupled to a nanosecond timeresolved transient mid-infrared （mid-IR） spectrometer system capable of investigating the protein folding kinetics with a temporal resolution of 50 ns after deconvolution of the instrumental response function. The mid-IR source is a liquid N2 cooled CO laser covering a spectral range of 5.0μm （2000 cm^-1）-6.5μm （1540 cm^-1）. The heating pulse was generated by a high pressure H2 Raman shifter at wavelength of 1.9μm. The maximum temperature-jump could reach as high as 26±1℃. The fast folding/unfolding dynamics of cytochrome C was investigated by the constructed system, providing an example.

Identifying Gas-Washing and Water-Washing of Oil Reservoirs by Fluorescence and Infrared Spectra of Single Oil Inclusion

Samples in the two oil fields with reported gas-washing and water-washing were collected for fluid inclusion analysis.Micro-fluorescence and Fourier infrared spectra of single oil inclusions were measured to study the different effects of gas-washing and water-washing on oil compositions.The results show that spectral parameter QF_(535)values of the oils altered by gas-washing were expanded toward decreasing and increasing,respectively.The CH_(2)/CH_(3)distribution range ratio does not expand significantly,but the peak values are averaged.And the distribution of H_(2)O/Alkanes has no change.The QF_(535)values of the oils affected by water-washing increased towards the increase direction,and the distribution ranges of both CH_(2)/CH_(3)and H_(2)O/Alkanes increase significantly.The changes of QF_(535)in light oil reservoirs altered by gas-washing and CH_(2)/CH_(3)in heavy oil reservoirs by water-washing are not obvious.Therefore,two spectral parameter distribution trend charts of light and heavy oil reservoirs are summarized to discriminate the gas-washing and water-washing processes.This study is of great practical significance to utilize fluid inclusion analysis to restructure stages and processes of petroleum accumulation.

Substituent Effect on Infrared Spectra and Thermodynamic Properties of Polynitroamino Substituted Cyclopentane and Cyclohexane

Density functional theory method was employed to study the effect of the nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct polycyclic or caged nitramines. Based on the optimized molecular structures of two groups of monocyclic nitramines at the B3LYP/6-31G^＊＊ level, the infrared （IR） spectra were obtained and assigned by harmonic vibrational analysis. The calculated results agree reasonably with the available experimental data. According to the principles of statistic thermodynamics, thermodynamic properties were derived from the IR spectra, which were linearly correlated with the number of nitroamino groups as well as the temperature. The contributions of nitroamino groups to thermodynamic properties are in accord with the group additivity.

Density Functional Theory Study of Infrared and Ultraviolet Spectra of Urea L-Malic Acid

Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory （DFT）. PBEPBE/6-31＋G（d,p） method, the optimal method for comparing the results from the several DFT methods, was chosen to study the molecular structure. Infrared and ultraviolet-visible spectra were obtained and compared with experiments. The ultraviolet-visible spectrum was also analyzed by the molecular orbital population. The geometries, and the infrared and ultraviolet-visible spectra in water were studied using DFT methods in combination with the polarized continuum model to predict the perturbations by the solvent effect.

Infrared Absorption Spectra of Serpentine Cat's Eye from Sichuan Province of China

Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained.

Studies on Lattice Vibrational Modes of Na_5Eu(WO_4)_4 Single Crystal by Raman Spectrum

Raman and infrared spectra of host luminescent crystal Na_5Eu(WO_4)_4 in several different geometric con- figurations have been investigated.The symmetrical species of lattice vibrational modes of the crystal have been analysed by means of the site group analysis method of group theory.The experimental vibrational modes have been assigned to A_g,B_g,E_g,A_u and E_u of crystal factor group C_(4h).Because the energies of stretching vibrational modes of(WO_4)^(2-)ion groups are very high(in the range of 755～940 cm^(-1)),multiphonon nonradiative transitions of ~5D_2→~5D_1 and ~5D_1→~5D_0 in Eu^(3+)will occur.So it causes Eu^(3+)ions in Na_5Eu(WO_4)_4 to emit ~5D_0→~5F_j(j=1,2,3,4)emissions mainly at room temperature and the emission light of Na_5Eu( WO_4)_4 has high red colour purity.

Crystal microstructure, infrared absorption, and microwave electromagnetic properties of (La_(1-x)Dy_x)_(2/3)Sr_(1/3)MnO_3

The manganite perovskite polycrystal samples of （La1-xDyx）2/3Sr1/3MnO3 （x = 0, 0.1, 0.2, 0.35, and 0.5） doped with Dy were prepared by solid state reaction in atmosphere to measure their X-ray diffraction （XRD） patterns, scanning electric microscope （SEM） images, infrared absorption spectra, and microwave electromagnetic properties. The displacement of the XRD peaks of the samples was found, and the 2θ increases from 0.05o to 0.5o. The grains of undoped La2/3Sr1/3MnO3 not only have the greatest size, but also the most regular shape. The size of the grains decreases as the Dy doping content increases from 0 to 0.5. The infrared absorption spectra of all samples were measured at room temperature. An absorption peak corresponding to the stretching vibration mode of Mn-O bonds appears within the range of 591-629 cm-1. The absorption peak shifts from a higher frequency to a lower one with the decrease of the average ionic radius of A-site. The frequency de- pendence of microwave-absorbing properties, imaginary components of the complex magnetic permeability μ＂ and dielectric permeability ε＂ for all samples was measured at room temperature from 8 to 13 GHz. The results show that the loss of microwave absorption can be attrib- uted to both the magnetic and electric losses. The increase of Dy content not only enhances the microwave absorption but also causes the displacement of the absorption peaks.

Infrared emissivity of transition elements doped ZnO

Infrared emissivity was studied in Zno.99Mo.olO （M is Mn, Fe or Ni） and Znl_xCoxO （x=0.01, 0.02, 0.03 and 0.04） powders synthesized by solid-state reaction at various temperatures. XRD patterns confirm the wurtzite structure of the prepared samples. No peaks of other phases arising from impurities are detected in Mn- and Co-doped ZnO, hut the peaks of ZnFe204 and NiO are observed in Zno.99Feo.010 and Zno.99Nio.o10. The SEM observations indicate that with larger grain sizes than those of Zn0.99Feo.010 and Zno.99Ni0.010, Co-doped ZnO exhibits smooth grain surfaces. The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.010 are much stronger than those in Co-doped ZnO. Co ions are dissolved into the ZnO lattice with Co2＋ state from XPS spectra analysis. The infrared emissivity results imply that the emissivity of Zno.99Ni0.010 is the highest （0.829） and that of Zno.99C00.010 is the lowest （0.784） at 1 200 ℃. The emissivity of Zno.99Co0.010 decreases to the minimum （0.752） at 1 150 ℃ and then increases with growing calcination temperature. As the Co doping content grows, the emissivity of Co-doped ZnO calcined at 1 200 ℃ falls to 0.758 in the molar fraction of 3% and then ascends.

Correlations between trace elements in pyrite and gold mineralization of gold deposits on the North China platform

By studying both the microscopic physical and chemical typomorphic characteristics of typical mineral pyrite samples associated with representative gold deposits on the north-central margin of the North China Platform,this paper seeks to identify macroscopic metallogenic mechanisms of gold deposits and to reveal the formation mechanism of lattice gold in pyrite.Typomorphic characteristics of pyrite reveal that pyrite grain size has a negative correlation with gold content.Cubic pyrite,as the dominant crystal form,contains more gold than pentagonal dodecahedral pyrite.Both pyrite crystal forms and chemical compositions indicate that the replacement style of gold deposit formed in a low saturability,low sulfur fugacity,and at temperatures either much higher or much lower than its best forming temperature;comparatively,that of the quartz vein style of gold deposit occurred under conditions with the best temperature,rich in sulfur,and with high sulfur fugacity.The Au/Ag ratios of the pyrites show that both the replacement and quartz vein styles of deposits are mesothermal and hypothermal,while the Co/Ni ratios of the pyrites indicate that the quartz vein style is of magmatic-hydrothermal origin.The X-ray diffraction intensity of pyrite rich in gold is lower than that of pyrite poor in gold at the quartz vein style.In general,with an increase in gold content in pyrite,the total sum intensityΣI decreases.The pyroelectricity coefficient has a negative correlation trend with the values of(Co+Ni+Se+Te)-As and(Co+Ni+Se+Te)/As.The pyrite pyroelectricity of the replacement style is N-type,indicating that it formed under low sulfur fugacity,while that of the quartz vein style is a mixture of P-N types,indicating that it formed under high sulfur fugacity.On the pyroelectricity-temperature diagram,pyrite of the replacement style is mainly distributed between 200 and 270°C,while that of the quartz vein style varies between 90–118 and274–386°C,demonstrating a multistage forming process.In contrast to previous researchers'conclusions,the authors confirm the existence of lattice gold in pyrites through the use of an electron paramagnetic resonance(EPR)test.Au in the form of Au~+,entering pyrite as an isomorph and producing electron–hole centers,makes the centers produce spin resonance absorption and results in EPR absorption peak II.The intensity of auriferous pyrite absorption peak II has certain direct positive correlations with pyrite gold content.The#I and#III absorption peaks of pyrites possibly result from the existence of Ni^(2+)and/or Cu^(2+).γ1,γ2,andγ3 are the strongest and most typical absorption peaks of the infrared spectra of the pyrites.Generally,with the increase in gold content in the pyrite samples,γ1,γ2,andγ3 tend to shift to higher wavenumbers,and the gold content in the pyrite samples has a positive correlation with their relative absorbance.

Influence of thermal history on conversion of aluminate species in sodium aluminate solution

It is necessary to clarify the influence of thermal history on the conversion of aluminate species in sodium aluminate solution in order to optimize Bayer alumina production. The interconversion of various solution species in the systems was investigated by measuring the infrared spectra of sodium aluminate solution with different compositions after separate heat treatment, dilution and concentration. The results show that increasing temperature or prolonging holding time favors the transformation of Al2O（OH）2- to Al—OH vibration（condensed Al O4 tetrahedral aluminate ion） at about 880 cm-1 and Al（OH）-4. A12O（OH）2-66 and Al—OH tetrahedral dimer ions convert rapidly to Al（OH）-4 during the dilution process; however, the back transformation of Al（OH）-4 to the Al—OH tetrahedral dimer ions can occur in diluted sodium aluminate solution. As for the concentration process, the transformation of Al（OH）-4 to A12O（OH）2-6 and Al—OH tetrahedral dimer ions can take place, while it is relatively difficult to transform to A12O（OH）2-6.

Molecular Dynamics Simulations of Silica Nanotube： Structural and Vibrational Properties Under Different Temperatures

Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental

Characteristics of coal re-oxidation based on microstructural and spectral observation

In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining,scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructure and chemical reaction of functional groups of eight coal samples at different ranks.Result shows that after initial oxidation,the surface morphology of pore are different,and the porosity of coal is increased and the oxygen adsorption capacity of coal is improved.The change of coal molecular structure and presence of a large amount of active oxygen-containing functional groups lead to increasing tendency of coal to further oxidation.In addition,the higher lever of the initial oxidation is,the easier the re-oxidation occurs.

Adsorption kinetics and thermodynamics of sodium butyl xanthate onto bornite in flotation

In this paper,the effect of sodium butyl xanthate(NaBX)adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic.The flotation results demonstrated that the recovery was the highest when pH was 9 in NaBX solution(4×10^?5 mol/L).The adsorption kinetics showed the reaction of NaBX on the bornite conformed to the second order kinetic equation;it belonged to the multimolecular layer adsorption of Freundlich model;the maximum adsorption rate constant was 0.30 g/(10^?6 mol·min),and the equilibrium adsorption capacity was 2.70×10^?6 mol/g.Thermodynamic calculation results indicated that the adsorption process was spontaneous chemisorption,and the adsorption products of NaBX on bornite surface were cupric butyl xanthate,ferric butyl xanthate and dixanthogen,which were confirmed by infrared spectrum measurements.

Spontaneous coal combustion producing carbon dioxide and water

Gas products from the process of coal oxidization and spontaneous combustion have been studied at different temperatures with FTI spectroscopic tests. With temperatures rising to about 30~100 ℃, water and carbon dioxide gas were formed and from about 105~150 ℃, carbon monoxide was produced. Using the DFT B3LYP method with a 6-311G basis set, the reaction system, where spontaneous combustion between coal and oxygen occurs and produces water and monoxide, has been studied, with the geometric configuration for all stagnation points on the potential reaction energy surface optimized. With a frequency analysis and an IRC method, transient formations were tested. Our results indicate that in the reaction of coal oxidization and spontaneous com-bustion producing carbon dioxide and water, oxygen molecules attack carbon atoms of the terminal of the propyl alcohol group on the lateral chain of benzene rings, which causes this propyl alcohol group to produce the acid (-CH2-CH2-COOH) group and water. This acid group continues its break up into carbon dioxide and the (-CH2-CH3) ethyl group. We have come to the conclusion that this water-and-carbon dioxide-production reaction is spontaneous, based on the observation of the energy released by the reaction.

Rheological Phase Synthesis and Characterization of Copper Monosalicylate

A new structural copper (II) monosalicylate, Cu(OC6H4C02)·H20, was synthesized by the rheological phase reaction method from salicylic acid and copper oxide in 1∶1 mole ratio. The structure was characterized by powder X-ray diffraction, IR and thermogravimetry. The Cu(OC6 H4 CC2)·H20 belongs to monoclinic system, with cell dimension:a=2.136 28(67),b=0. 657 84(22),c=l. 594 09(50) nm, β=108.434(25) ,V=2.125 28(83) nm3,Z=12, Dcalc=2.041 kg·L?1,D obs=2.003 kg·L?1. The crystal water was lost at 96–250°C. The determined magnetic moment and magnetic susceptibility were 1. 947 B. M. and 6. 546×10?6 (287. 20 K), respectively.