Vibrational properties of silicon nanopowders are discussed with reference to Raman spectroscopic measurements. The powders were produced in a low pressure rf plasma from the cluster induced agglomeration of positive ...Vibrational properties of silicon nanopowders are discussed with reference to Raman spectroscopic measurements. The powders were produced in a low pressure rf plasma from the cluster induced agglomeration of positive ions formed during the dissociation of silane. Influence of thermal treatment and the crystallization phenomena of the powder were studied. Raman spectroscopic measurements reveal size quantization effects for the particles as well as the existence of partially ordered regions in the apparently amorphous primary particles. The crystalline and amorphous volume fraction in the material were calculated from the relative spectraI intensities. The results obtained in these experiments are consistent with the observations from recent high resolution transmission electron microscopy studies of these powders展开更多
Infrared spectra of (n-C_9H_(19)NH_3)_2CuCl_4 in three solid phases were investigated. It was found that the phase transition at T_(cl)(25℃) arises from the change of the interaction and packing structure of the chai...Infrared spectra of (n-C_9H_(19)NH_3)_2CuCl_4 in three solid phases were investigated. It was found that the phase transition at T_(cl)(25℃) arises from the change of the interaction and packing structure of the chain. The phase transition at T_(c2)(34℃)is related to the change of a partial conformational order-disorder. The GTC or GTG' and small concentration of TG structure near CH_3 group exist in phase Ⅲ (above 38℃).展开更多
A series of new dansylamide derivatives have been synthesized and the specific bindingaffinity of such fluorophores to nucleic acids has been investigated by using absorption, circulardichroism (CD), fluorescence and ...A series of new dansylamide derivatives have been synthesized and the specific bindingaffinity of such fluorophores to nucleic acids has been investigated by using absorption, circulardichroism (CD), fluorescence and atomic force microscopy (AFM). The results indicate that thepositive charge of the ligand and the stacking between the dansy1 part of the ligand and theDNA base pair may play an important role when binding to polynucleotides.展开更多
The vibrational spectra of both pure DPPC liposomes and DPPC multilayers reconstituted with Ge-132 are reported as a function of temperature from 290 to 330K.The results show that the addition of Ge-132 results in sup...The vibrational spectra of both pure DPPC liposomes and DPPC multilayers reconstituted with Ge-132 are reported as a function of temperature from 290 to 330K.The results show that the addition of Ge-132 results in suppression of the pretransition behavior and reduction of temperature of the main transition for reconstituted system.The results also show that the degree of rigidity of the acyl chain in the presence of Ge-132 is lower than that in pure DPPC dispersion within the investigated temperature range.展开更多
The molecular interactions between Nd^(3+), Gd^(3+)and Yb^(3+) and DPPC in multibilayer have been studied by Fourier transform infrared spectroscopy. The results show that incorporations of the lanthanide ions conside...The molecular interactions between Nd^(3+), Gd^(3+)and Yb^(3+) and DPPC in multibilayer have been studied by Fourier transform infrared spectroscopy. The results show that incorporations of the lanthanide ions considerably shift the gel to liquid-crystal phase transition to higher temperatures. The incorporations of Gd^(3+) and Yb^(3+) obviously reduce the cooperations of the transition. The phosphate region of the spectra indicates that the Ln^(3+) binding to DPPC forms DPPC-Ln^(3+)complex and the Lna^(3+)binding is not dependent on the phase state of DPPC. The C-H stretching region of the spectra suggests that the incorporation of Ln^(3+)increases the conformational order of DPPC both in gel and in liquid-crystal phase as a result of the reduction of gauche rotamers.展开更多
The detection of the microwave-discharged species of methyl iodide by HeI photoelectron spectroscopy(UPS)is reported for the first time.The UPS spectra of I_2 and HI molecules clearly appeared in the spectrum of micro...The detection of the microwave-discharged species of methyl iodide by HeI photoelectron spectroscopy(UPS)is reported for the first time.The UPS spectra of I_2 and HI molecules clearly appeared in the spectrum of microwave-discharged species of methyl iodide,The mechanism of the change of methyl iodide under microwave discharge was proposed,The result provides the basis for understanding depletion of the ozone shell of the atomsphere by halogenated methane.展开更多
Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded forma...Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.展开更多
An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI＋Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states ...An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI＋Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments （PDMs） and the spin-orbit （SO） matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of （2）1//2 state. Finally, the transition properties from the （2）1//2, （1）3//2 and （3）1//2 states to the ground state X2∑＋1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes.展开更多
The interaction between a cationic dye Methylene Blue(MB)and an anionic surfactant sodium dodecyl sulfate(SDS)with the presence of Cd2+was investigated spectrophotometrically in a certain concentration range.The spect...The interaction between a cationic dye Methylene Blue(MB)and an anionic surfactant sodium dodecyl sulfate(SDS)with the presence of Cd2+was investigated spectrophotometrically in a certain concentration range.The spectrophotometric measurements of dye-metal ion-surfactant system were carried out.The results indicated that the SDS concentration had a significant influence on the dye spectrum,while the addition of Cd2~hardly caused change of the maximum value of absorbance.According to this observation,we concluded that electrostatic and hydrophobic interaction between dye and surfactant occurred up to a certain level,and the homo-ions Cd2+almost exerted no effect on the dye-surfactant complexation,establishing a theoretical foundation for simultaneous removal of organic dye and heavy metal using foam fractionation.Meanwhile,the effects of their interaction on foam performance were investigated.The results showed that the addition of Cd2+favored the tendency to ameliorate foam properties just contrary to MB.The feasibility of foam separation for dye and heavy metal removal from simulated wastewater was also confirmed using a continuous foam fractionator.In the simultaneous removal process,with the initial SDS concentration ranging from 0.5 to 5.0 retool/L,the maximum removal efticiencies of MB and Cd2+were obtained as 99.69%and 99.61%,respectively.The enrichment ratios were reduced from 24.34 to 7.65 for MB and from 22.01 to 3.35 for Cd2+.展开更多
Fourier transform infrared (FTIR) spectroscopy has beenextensively employed in flotation research. The work done by theauthor and co-workers has been reported. A comparison has been madeamong the different FTIR spectr...Fourier transform infrared (FTIR) spectroscopy has beenextensively employed in flotation research. The work done by theauthor and co-workers has been reported. A comparison has been madeamong the different FTIR spectroscopic techniques, e.g., transmissionFTIR spectroscopy, diffuse reflectance infrared Fourier transform(DRIFT) spectroscopy, and attenuated total reflectance (ATR) FTIRspectroscopy.展开更多
Aluminum organic coprecipitates play important roles in the transport of oxyanions in soil environment.A new polynuclear aluminum organomineral precipitate(Al13-oxalate precipitate) was prepared to investigate the ads...Aluminum organic coprecipitates play important roles in the transport of oxyanions in soil environment.A new polynuclear aluminum organomineral precipitate(Al13-oxalate precipitate) was prepared to investigate the adsorption behavior of arsenate and phosphate on noncrystalline aluminum precipitates.Important thermodynamic parameters for adsorption reaction were evaluated using macroscopic adsorption data and equations.The result showed that,the adsorption reaction basically is a diffusion process.FTIR spectroscopic studies have provided evidence for the formation of two different types of complexes in substrate,protonated bidentate and deprotonated bidentate complexes at pH 4 and pH≥6,respectively.The classic competitive adsorption and XPS studies both indicated that phosphate has stronger chemical interaction with substrate than arsenate.The findings of XPS studies revealed that the precipitate substrate can act as Lewis acid when adsorbing oxyanions.展开更多
^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petrolife...^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petroliferous basin India. It is found that iron is mainly distributed in high spin Fe^3＋and Fe^2＋ state in clay minerals. The plot of Fe^2＋/（Fe^2＋＋ Fe^3＋） indicates the presence of poor redox conditions in the samples.Results obtained are also compared with those already reported in the literature. This comparison shows that there may exist a correlation between prospecting of the basin, the redox environment in sediments and the nature of iron bearing minerals distributed in the sedimentary sequence.展开更多
The discovery of high temperature superconductivity in single-layer FeSe/SrTiO3 provides a new platform for ex- ploring superconductivity and pursuing higher Tc （superconducting transition temperature） through fabri...The discovery of high temperature superconductivity in single-layer FeSe/SrTiO3 provides a new platform for ex- ploring superconductivity and pursuing higher Tc （superconducting transition temperature） through fabricating artificial heterostructures. In this paper, we review the recent progress in studying and tuning the interfacial superconductivity in single-layer FeSe, through the combined in-situ spectroscopic studies and atomic-scale engineering. By fabricating arti- ficial heterostructures, various interfacial factors were tuned, and the corresponding evolutions of electronic structure and superconducting gap behavior were investigated. These studies enrich the current understanding on the interfacial superconductivity, and provide clues for further enhancing Tc through interface engineering.展开更多
The FT-IR and FT-Raman spectra of complexes (C5H5)2TiCl2(Ⅰ), (C5H4Me)2TiCl2 (Ⅱ) and (C5HMe4)2TiCl2(Ⅲ) have been obtained and discussed. The FT-Raman spectral data pro- vide some new vibrational information about co...The FT-IR and FT-Raman spectra of complexes (C5H5)2TiCl2(Ⅰ), (C5H4Me)2TiCl2 (Ⅱ) and (C5HMe4)2TiCl2(Ⅲ) have been obtained and discussed. The FT-Raman spectral data pro- vide some new vibrational information about complexes (Ⅰ), (Ⅱ) and (Ⅲ). The assignments of cyclopentadienyl vibrational modes and skeletal vibrational modes have been made.展开更多
XRD, IR, NMR and a 'tracer method' are used to investigate two hydrated sodium aluminates. It has been found that the compositions of these two compounds are 4Na2O-Al2O-3-12H2O and Na2O-Al2O3-2.5H2O, respecttv...XRD, IR, NMR and a 'tracer method' are used to investigate two hydrated sodium aluminates. It has been found that the compositions of these two compounds are 4Na2O-Al2O-3-12H2O and Na2O-Al2O3-2.5H2O, respecttvely. The aluminate anion in the former consists of condensed AlO4 tetrahedra.展开更多
Mechanical alloying (MA) was employed to produce supersaturated solid solutions of Fe1-xCux,which is virtually immiscible under an equilibrium condition at ambjent temperature. The X-ray diffraction results show that ...Mechanical alloying (MA) was employed to produce supersaturated solid solutions of Fe1-xCux,which is virtually immiscible under an equilibrium condition at ambjent temperature. The X-ray diffraction results show that the solutions formed in the concentration ranges of x≤0.1 5 and x≥0.40 are of bcc structure of iron and fcc structure of copper. respectively. For the region in between.however, the alloy obtained is a mixture of bcc plus fcc phases. The Mossbauer spectrum of the solid solution of a single phase could be fitted by two sub-spectra with hyperfine magnetic fields of 200 and 250 kOe. respectively. suggesting that there must exist two forms of coordination in the solution. While to fit the spectrum for the solution with mixed structu re. three Sub-spectra. including a spectrum of α-Fe, should be used. The variation of the Mossbauer spectra of Fe60Cu40 with milling time as well as annealing temperature was systematically studied. This may be ascribed to the changes of the number of nearest neighboring atoms of iron in the processes of formation and decomposition of the solid solution during milling and annealing展开更多
Nanocrystalline CdSe thin film prepared by chemical solution deposition was imaged in air with a scanning tunnelling microscope(STM). Scanning tunnelling current spectroscopy(STS) was taken at a fixed tip - sample sep...Nanocrystalline CdSe thin film prepared by chemical solution deposition was imaged in air with a scanning tunnelling microscope(STM). Scanning tunnelling current spectroscopy(STS) was taken at a fixed tip - sample separation. Tunnelling current(i) - voltage(v) curve and differential conductance spectrum show an n-type schottky rectifying behaviour and yield a direct measure of band gap energy. An increase of bandgap energy (1.8 - 2.1eV) was measured indicating energy quantization of this particular thin film.,展开更多
The complex of Eu（IH） with 1-（6-hydroxy- 1-naphthyl）- 1,3-butanedione （HNBD） was prepared for the first time and characterized by elemental analysis, IR, UV, fluorescence spectrum, and DTA-TG-DTG techniques. The...The complex of Eu（IH） with 1-（6-hydroxy- 1-naphthyl）- 1,3-butanedione （HNBD） was prepared for the first time and characterized by elemental analysis, IR, UV, fluorescence spectrum, and DTA-TG-DTG techniques. The IR and UV-visible spectra showed that Eu（Ⅲ） ion was coordinated to the HNBD ligand. The fluorescence spectrum showed the presence of Eu^3＋ characteristic emission. The TG-DTA-DTG curves showed that the thermal decomposition of the anhydrous complex was a two-stage process and the final residue was Eu2O3. The thermal decomposition kinetic parameters of the complex were evaluated from TG-DTG data by using three kinds of integral methods （Coat-Redfem equation, Horowitz and Metzger equation, Madhusudanan-Krishnan-Ninan equation）. The kinetic parameters of the first stage are E^＊ = 164.02 kJ.moll, A = 1.31 × 10^15 s^-l, AS^＊= 42.27 J·K^-l·mol^-l, △H^＊ = 159.51 kJ·mol^-l, △G^＊= 136.54 kJ·mol^-l, and n = 3.1, those of the second stage are E^＊= 128.52 kJ·mol^-l, A = 1.44× 106 s^-1, △S^＊= - 136.89 J·K^-l·mol^-l, △H^＊ = 120.41 kJ·mol^-l, △G^＊= 283.85 kJ·mol^-l, and n = 1.1.展开更多
The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A ...The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A drastic quenching of fluorescence from the Ru(bpy)_3^(2+) subunit by the covalently attached quencher sub- unit Ni(cyclam)^(2+) was observed for complex 3,and the mechanism was discussed.展开更多
In its cationic,trivalent form,Chromium(Cr)it is a micronutrient,and exhibits low environmental mobility.In hexavalent form,however,it is a human carcinogen and also highly mobile.Climate is a key environmental factor...In its cationic,trivalent form,Chromium(Cr)it is a micronutrient,and exhibits low environmental mobility.In hexavalent form,however,it is a human carcinogen and also highly mobile.Climate is a key environmental factor controlling weathering rates and stability of primary and secondary Cr-bearing minerals.Knowledge of Cr oxidation state and mineral residence is therefore essential to estimating the risk posed by Cr in serpentinites,chromite mine wastes,and soils developed on these parent materials.X-ray absorption spectroscopy(XAS)is currently the best available technique for determination of the relative abundance of Cr(III)and Cr(VI)in situ(that is,without digestion of solid phases).A brief review of relevant XAS studies of is presented below,focusing on studies in tropical climates1,as they will be most relevant to eastern Cuba’s extensively serpentinized ophiolite belt.Cr(III)-bearing spinels are usually the dominant and most refractory Cr host in ultramafic rocks.Previous XAS studies2 indicate that in tropical climates,Cr-spinels weather rapidly to form Cr(III)-bearing secondary Fe(III)(hydr)oxides(goethite,hematite).Manganese(Mn)is also enriched in ultramafic rocks2;as Mn(IV),it can also co-precipitate with Fe(III)(hydr)oxides,or form its own secondary(hydr)oxides.A previous study found up to 20%Cr(VI)in in a tropical,serpentine soil that contained substantial Mn,and a strong correlation between the*amounts of Cr(VI)and Mn(IV)in the soil profile2.Theresults of several XAS studies suggest that a close association of Mn(IV)and Cr(III)in secondary Fe(hydr)oxides is necessary for oxidation of Cr(III)to Cr(VI)via electron transfer reactions with Mn(IV);however,additional XAS studies have shown that organic matter3and Cr-bearing aluminosilicates4 may also be important sources of Cr(III)to the environment under specific conditions.The stability and fate of Cr has not been studied in detail for these two host phase types,to the best of our knowledge.Access to XAS facilities to perform Cr geochemical experiments is limited and will only become more so in the future.We are working to develop and apply(micro)Raman spectroscopy to evaluate Cr oxidation state and mineral residence(in crystalline and amorphous materials).In addition to standard Raman scattering,we are employing resonance Raman(785 nm laser)to enhance signal from Cr(VI)-bearing phases and laser-stimulated photoluminescence to identify Cr(III)associated with Al-rich alteration products展开更多
文摘Vibrational properties of silicon nanopowders are discussed with reference to Raman spectroscopic measurements. The powders were produced in a low pressure rf plasma from the cluster induced agglomeration of positive ions formed during the dissociation of silane. Influence of thermal treatment and the crystallization phenomena of the powder were studied. Raman spectroscopic measurements reveal size quantization effects for the particles as well as the existence of partially ordered regions in the apparently amorphous primary particles. The crystalline and amorphous volume fraction in the material were calculated from the relative spectraI intensities. The results obtained in these experiments are consistent with the observations from recent high resolution transmission electron microscopy studies of these powders
文摘Infrared spectra of (n-C_9H_(19)NH_3)_2CuCl_4 in three solid phases were investigated. It was found that the phase transition at T_(cl)(25℃) arises from the change of the interaction and packing structure of the chain. The phase transition at T_(c2)(34℃)is related to the change of a partial conformational order-disorder. The GTC or GTG' and small concentration of TG structure near CH_3 group exist in phase Ⅲ (above 38℃).
文摘A series of new dansylamide derivatives have been synthesized and the specific bindingaffinity of such fluorophores to nucleic acids has been investigated by using absorption, circulardichroism (CD), fluorescence and atomic force microscopy (AFM). The results indicate that thepositive charge of the ligand and the stacking between the dansy1 part of the ligand and theDNA base pair may play an important role when binding to polynucleotides.
文摘The vibrational spectra of both pure DPPC liposomes and DPPC multilayers reconstituted with Ge-132 are reported as a function of temperature from 290 to 330K.The results show that the addition of Ge-132 results in suppression of the pretransition behavior and reduction of temperature of the main transition for reconstituted system.The results also show that the degree of rigidity of the acyl chain in the presence of Ge-132 is lower than that in pure DPPC dispersion within the investigated temperature range.
文摘The molecular interactions between Nd^(3+), Gd^(3+)and Yb^(3+) and DPPC in multibilayer have been studied by Fourier transform infrared spectroscopy. The results show that incorporations of the lanthanide ions considerably shift the gel to liquid-crystal phase transition to higher temperatures. The incorporations of Gd^(3+) and Yb^(3+) obviously reduce the cooperations of the transition. The phosphate region of the spectra indicates that the Ln^(3+) binding to DPPC forms DPPC-Ln^(3+)complex and the Lna^(3+)binding is not dependent on the phase state of DPPC. The C-H stretching region of the spectra suggests that the incorporation of Ln^(3+)increases the conformational order of DPPC both in gel and in liquid-crystal phase as a result of the reduction of gauche rotamers.
文摘The detection of the microwave-discharged species of methyl iodide by HeI photoelectron spectroscopy(UPS)is reported for the first time.The UPS spectra of I_2 and HI molecules clearly appeared in the spectrum of microwave-discharged species of methyl iodide,The mechanism of the change of methyl iodide under microwave discharge was proposed,The result provides the basis for understanding depletion of the ozone shell of the atomsphere by halogenated methane.
文摘Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11564019,11574114,11147158,91221301 and 11264020the Natural Science Foundation of Jilin Province under Grant No 20150101003JC
文摘An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI＋Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments （PDMs） and the spin-orbit （SO） matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of （2）1//2 state. Finally, the transition properties from the （2）1//2, （1）3//2 and （3）1//2 states to the ground state X2∑＋1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes.
基金supported by the National Natural Science Foundation of China (No. 50608028,50808073,50978088,51008121,51039001)the New Century Excellent Talents in University from the Ministry of Education of China (No. NCET-08-0180,NCET-08-0181)
文摘The interaction between a cationic dye Methylene Blue(MB)and an anionic surfactant sodium dodecyl sulfate(SDS)with the presence of Cd2+was investigated spectrophotometrically in a certain concentration range.The spectrophotometric measurements of dye-metal ion-surfactant system were carried out.The results indicated that the SDS concentration had a significant influence on the dye spectrum,while the addition of Cd2~hardly caused change of the maximum value of absorbance.According to this observation,we concluded that electrostatic and hydrophobic interaction between dye and surfactant occurred up to a certain level,and the homo-ions Cd2+almost exerted no effect on the dye-surfactant complexation,establishing a theoretical foundation for simultaneous removal of organic dye and heavy metal using foam fractionation.Meanwhile,the effects of their interaction on foam performance were investigated.The results showed that the addition of Cd2+favored the tendency to ameliorate foam properties just contrary to MB.The feasibility of foam separation for dye and heavy metal removal from simulated wastewater was also confirmed using a continuous foam fractionator.In the simultaneous removal process,with the initial SDS concentration ranging from 0.5 to 5.0 retool/L,the maximum removal efticiencies of MB and Cd2+were obtained as 99.69%and 99.61%,respectively.The enrichment ratios were reduced from 24.34 to 7.65 for MB and from 22.01 to 3.35 for Cd2+.
文摘Fourier transform infrared (FTIR) spectroscopy has beenextensively employed in flotation research. The work done by theauthor and co-workers has been reported. A comparison has been madeamong the different FTIR spectroscopic techniques, e.g., transmissionFTIR spectroscopy, diffuse reflectance infrared Fourier transform(DRIFT) spectroscopy, and attenuated total reflectance (ATR) FTIRspectroscopy.
基金funded jointly by the National Natural Science Foundation of China (Grant No. 41002128)the Open Research Project of State Key Laboratory of Coal Resource & Mining Safety (SKLCRSM09KFB05)Doctorial Research Fund of Southwest University of Science and Technology (09ZX7115)
文摘Aluminum organic coprecipitates play important roles in the transport of oxyanions in soil environment.A new polynuclear aluminum organomineral precipitate(Al13-oxalate precipitate) was prepared to investigate the adsorption behavior of arsenate and phosphate on noncrystalline aluminum precipitates.Important thermodynamic parameters for adsorption reaction were evaluated using macroscopic adsorption data and equations.The result showed that,the adsorption reaction basically is a diffusion process.FTIR spectroscopic studies have provided evidence for the formation of two different types of complexes in substrate,protonated bidentate and deprotonated bidentate complexes at pH 4 and pH≥6,respectively.The classic competitive adsorption and XPS studies both indicated that phosphate has stronger chemical interaction with substrate than arsenate.The findings of XPS studies revealed that the precipitate substrate can act as Lewis acid when adsorbing oxyanions.
文摘^57Fe Mossbauer spectroscopic study was carried out on the organic rich sedimentary samples collected at different depth intervals from newly drilled test well Chinnewala Tibba-1（CT-1） located in Jaisalmer Petroliferous basin India. It is found that iron is mainly distributed in high spin Fe^3＋and Fe^2＋ state in clay minerals. The plot of Fe^2＋/（Fe^2＋＋ Fe^3＋） indicates the presence of poor redox conditions in the samples.Results obtained are also compared with those already reported in the literature. This comparison shows that there may exist a correlation between prospecting of the basin, the redox environment in sediments and the nature of iron bearing minerals distributed in the sedimentary sequence.
基金supported by the National Natural Science Foundation of China and the National Basic Research Program of China(Grant Nos.2012CB921402,2011CB921802,and 2011CBA00112)
文摘The discovery of high temperature superconductivity in single-layer FeSe/SrTiO3 provides a new platform for ex- ploring superconductivity and pursuing higher Tc （superconducting transition temperature） through fabricating artificial heterostructures. In this paper, we review the recent progress in studying and tuning the interfacial superconductivity in single-layer FeSe, through the combined in-situ spectroscopic studies and atomic-scale engineering. By fabricating arti- ficial heterostructures, various interfacial factors were tuned, and the corresponding evolutions of electronic structure and superconducting gap behavior were investigated. These studies enrich the current understanding on the interfacial superconductivity, and provide clues for further enhancing Tc through interface engineering.
基金Supported by the National Natural Science Foundation of China.
文摘The FT-IR and FT-Raman spectra of complexes (C5H5)2TiCl2(Ⅰ), (C5H4Me)2TiCl2 (Ⅱ) and (C5HMe4)2TiCl2(Ⅲ) have been obtained and discussed. The FT-Raman spectral data pro- vide some new vibrational information about complexes (Ⅰ), (Ⅱ) and (Ⅲ). The assignments of cyclopentadienyl vibrational modes and skeletal vibrational modes have been made.
文摘XRD, IR, NMR and a 'tracer method' are used to investigate two hydrated sodium aluminates. It has been found that the compositions of these two compounds are 4Na2O-Al2O-3-12H2O and Na2O-Al2O3-2.5H2O, respecttvely. The aluminate anion in the former consists of condensed AlO4 tetrahedra.
文摘Mechanical alloying (MA) was employed to produce supersaturated solid solutions of Fe1-xCux,which is virtually immiscible under an equilibrium condition at ambjent temperature. The X-ray diffraction results show that the solutions formed in the concentration ranges of x≤0.1 5 and x≥0.40 are of bcc structure of iron and fcc structure of copper. respectively. For the region in between.however, the alloy obtained is a mixture of bcc plus fcc phases. The Mossbauer spectrum of the solid solution of a single phase could be fitted by two sub-spectra with hyperfine magnetic fields of 200 and 250 kOe. respectively. suggesting that there must exist two forms of coordination in the solution. While to fit the spectrum for the solution with mixed structu re. three Sub-spectra. including a spectrum of α-Fe, should be used. The variation of the Mossbauer spectra of Fe60Cu40 with milling time as well as annealing temperature was systematically studied. This may be ascribed to the changes of the number of nearest neighboring atoms of iron in the processes of formation and decomposition of the solid solution during milling and annealing
文摘Nanocrystalline CdSe thin film prepared by chemical solution deposition was imaged in air with a scanning tunnelling microscope(STM). Scanning tunnelling current spectroscopy(STS) was taken at a fixed tip - sample separation. Tunnelling current(i) - voltage(v) curve and differential conductance spectrum show an n-type schottky rectifying behaviour and yield a direct measure of band gap energy. An increase of bandgap energy (1.8 - 2.1eV) was measured indicating energy quantization of this particular thin film.,
基金financially supported by the Important Foundation of the Educational Commission of Hubei Province (No. Z200622001)the Natural Science Foundation of the Educational Commission of Hubei Province, China (No. J200522002)
文摘The complex of Eu（IH） with 1-（6-hydroxy- 1-naphthyl）- 1,3-butanedione （HNBD） was prepared for the first time and characterized by elemental analysis, IR, UV, fluorescence spectrum, and DTA-TG-DTG techniques. The IR and UV-visible spectra showed that Eu（Ⅲ） ion was coordinated to the HNBD ligand. The fluorescence spectrum showed the presence of Eu^3＋ characteristic emission. The TG-DTA-DTG curves showed that the thermal decomposition of the anhydrous complex was a two-stage process and the final residue was Eu2O3. The thermal decomposition kinetic parameters of the complex were evaluated from TG-DTG data by using three kinds of integral methods （Coat-Redfem equation, Horowitz and Metzger equation, Madhusudanan-Krishnan-Ninan equation）. The kinetic parameters of the first stage are E^＊ = 164.02 kJ.moll, A = 1.31 × 10^15 s^-l, AS^＊= 42.27 J·K^-l·mol^-l, △H^＊ = 159.51 kJ·mol^-l, △G^＊= 136.54 kJ·mol^-l, and n = 3.1, those of the second stage are E^＊= 128.52 kJ·mol^-l, A = 1.44× 106 s^-1, △S^＊= - 136.89 J·K^-l·mol^-l, △H^＊ = 120.41 kJ·mol^-l, △G^＊= 283.85 kJ·mol^-l, and n = 1.1.
文摘The spectroscopic properties for a recently synthesized hetero-metallo- binuclear complex Ru(bpy)_2 (bpy-cyclam-Ni)^(4+)(3)and its related complexes 1 and 2 were investigated by UV-vis and emission spectral methods.A drastic quenching of fluorescence from the Ru(bpy)_3^(2+) subunit by the covalently attached quencher sub- unit Ni(cyclam)^(2+) was observed for complex 3,and the mechanism was discussed.
文摘In its cationic,trivalent form,Chromium(Cr)it is a micronutrient,and exhibits low environmental mobility.In hexavalent form,however,it is a human carcinogen and also highly mobile.Climate is a key environmental factor controlling weathering rates and stability of primary and secondary Cr-bearing minerals.Knowledge of Cr oxidation state and mineral residence is therefore essential to estimating the risk posed by Cr in serpentinites,chromite mine wastes,and soils developed on these parent materials.X-ray absorption spectroscopy(XAS)is currently the best available technique for determination of the relative abundance of Cr(III)and Cr(VI)in situ(that is,without digestion of solid phases).A brief review of relevant XAS studies of is presented below,focusing on studies in tropical climates1,as they will be most relevant to eastern Cuba’s extensively serpentinized ophiolite belt.Cr(III)-bearing spinels are usually the dominant and most refractory Cr host in ultramafic rocks.Previous XAS studies2 indicate that in tropical climates,Cr-spinels weather rapidly to form Cr(III)-bearing secondary Fe(III)(hydr)oxides(goethite,hematite).Manganese(Mn)is also enriched in ultramafic rocks2;as Mn(IV),it can also co-precipitate with Fe(III)(hydr)oxides,or form its own secondary(hydr)oxides.A previous study found up to 20%Cr(VI)in in a tropical,serpentine soil that contained substantial Mn,and a strong correlation between the*amounts of Cr(VI)and Mn(IV)in the soil profile2.Theresults of several XAS studies suggest that a close association of Mn(IV)and Cr(III)in secondary Fe(hydr)oxides is necessary for oxidation of Cr(III)to Cr(VI)via electron transfer reactions with Mn(IV);however,additional XAS studies have shown that organic matter3and Cr-bearing aluminosilicates4 may also be important sources of Cr(III)to the environment under specific conditions.The stability and fate of Cr has not been studied in detail for these two host phase types,to the best of our knowledge.Access to XAS facilities to perform Cr geochemical experiments is limited and will only become more so in the future.We are working to develop and apply(micro)Raman spectroscopy to evaluate Cr oxidation state and mineral residence(in crystalline and amorphous materials).In addition to standard Raman scattering,we are employing resonance Raman(785 nm laser)to enhance signal from Cr(VI)-bearing phases and laser-stimulated photoluminescence to identify Cr(III)associated with Al-rich alteration products
