Mossbauer Spectroscopic Studies on a Supersaturated Solid Solution of Fe-Cu Formed by Mechanical Alloying

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

Scanning Tunneling Microscopic and Scanning Tunneling Spectroscopic Studies of Nanocrystalline CdSe Thin Film

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.,

SPECTROSCOPIC STUDIES ON A HETEROMETALLOBINUCLEAR COMPLEX IN WHICH Ru(BPY)_3^(2+)WAS COVALENTLY ATTACHED TO N_i^-(CYCLAM)^(2+)

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.

The Fate of Chromium in Weathered Ultramafic Rocks and Their Derivitative Soils in Cuba: Clues from Spectroscopic Studies

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

IN-SITU TIME-RESOLVED RAMAN SPECTROSCOPIC STUDIES OF SILVER ELECTRODE IN NaSCN SOLUTION

In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained.

CALORIMETRIC AND RAMAN SPECTROSCOPIC STUDIES ON THE INTERACTION OF LANTHANOID IONS WITH DIPALMITOYLPHOSPHATIDYLCHOLINE BILAYER

The interactions of lanthanoid ions with dipalmitoylphosphatidylcholine bilayer were studied by DSC and Raman spectroscopy.The results show that the addition of lanthanoid ions causes a considerable increase of the gel to liquid crystalline transition temperature of phospholipid and a reduction of order of lateral packing and conformation of acyl chains in SUVs.

SPECTROSCOPIC STUDIES OF SEVERAL MESO-SUBSTITUTED ZINC TETRABENZOPORPHYRINS

The electronic spectroscopic properties of several meso-substituted zinc tetrabenzoporphyrins(ZnTBP,ZnTMTBP, ZnTPTBP,ZnTTTBP and ZnTNTBP)have been investigated in toluene.The lifetimes determined showed that the fluorescence of these compounds decay with good double exponentials.

Synthesis,Structure,and Spectroscopic Studies of a Chiral Supramolecular Complex with Excellent Semiconductor Property

A novel chiral copper（Ⅱ） complex with racemic 1,2-diaminocyclohexane and iodide,[Cu（Ⅱ）（1,2-diaminocyclohexane）_3]（I）_2·3H_2O（1） has been synthesized and structurally characterized by X-ray single-crystal diffraction,elemental analysis,infrared spectroscopy,Raman spectroscopy and thermogravimetric analysis. In complex 1,the CuⅡ ion was coordinated by six nitrogen atoms of three 1,2-diaminocyclohexane molecules. The structure of complex 1 can be described as a supramolecular 3D-like structure which was formed by intermolecular hydrogen-bonding interactions between mononuclear molecules,uncoordinated water molecules and two iodide anions. UV-vis absorption spectrum and surface photovoltage properties of complex 1 have also been studied.

Fourier Transform Infrared Spectroscopic Studies in Flotation

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.

In-situ spectroscopic studies and interfacial engineering on FeSe/oxide heterostructures: Insights on the interfacial superconductivity

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.

FT-Infrared and FT-Raman Spectroscopic Studies of Complexes (C_5H_5)_2TiCl_2,(C_5H_4Me)_2TiCl_2 and (C_5HMe_4)_2TiCl_2

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.

COMPOSITION AND SPECTROSCOPIC STUDIES OF HYDRATED SODIUM ALUMINATE COMPOUNDS

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.

Preparation and spectroscopic, and thermal decomposition kinetic studies of europium(Ⅲ) complex [Eu(HNBD)_3] (HNBD: 1-(6-hydroxy-1-naphthyl)-1,3-butanedione)

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.

Spectroscopic studies of dye-surfactant interactions with the co-existence of heavy metal ions for foam fractionation

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＋.

Spectroscopic and macroscopic studies of the adsorption of arsenate and phosphate on polynuclear aluminum organomineral precipitates

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.

Role of Bridge-bonded Formate in Formic Acid Dehydration to CO at Pt Electrode： Electrochemial in-situ Infrared Spectroscopic Study

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.

Raman Spectroscopic Study of Silicon Nanopowders

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

INFRARED SPECTROSCOPIC STUDY OF STRUCTURE TRANSITION IN THE PEROVSKITE-TYPE LAYER COMPOUND: (n-C_9H_(19_NH_3)_2CuCl_4

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℃).

Spectroscopic Study of the Interactionbetween New Fluorescent Dyes with Nucleic Acids

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.

VIBRATIONAL SPECTROSCOPIC STUDY OF THE INTERACTION BETWEEN Ge-132 AND DIPALMITOYLPHOSPHATIDYLCHOL INE

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.