The v-v energy transfer of highly vibrationally excited states (I)──Vibrational quenching of CO(v) by CO_2

The relaxation of the highly vibrationally excited CO (v=1-8) by CO\-2 is studied by time_resolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr\-3 with O\-2 generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v=1-8) to CO 2 molecules are obtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (10 -14 cm 3·molecule -1·s -1), respectively. A two_channel energy transfer model can explain the feature of the quenching of CO(v) by CO 2. For the lower vibrational states of CO, the vibrational energy transfers preferentially to the υ\-3 mode of CO 2. For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the υ\-1 mode of CO 2.     

Polarized Emission of Molecular Film With Lanthanide (Ⅲ) Complex

1 Results In the coordination system by using complexation with organic ligand, the ff emission of lanthanide(Ⅲ) (Ln(Ⅲ)) is induced the excitation energy transfer form the organic chromophore under the light-irradiation. However, there are not so much number of reports to discuss the energy relaxation mechanism in such complexes with Ln(Ⅲ). Recently, we succeeded firstly to estimate the rate constant of the energy transfer between the ligand and Ln(Ⅲ) in Pr(Ⅲ)-phenanthroline analogs[1]. Here, we will di...     

First-principle study of interaction of H2 and H2O molecules with (ZnO)n(n=3?6) ring clusters

A density functional calculation was performed to investigate the impact of hydrogen and water molecules on zinc oxide clusters (ZnO)n=3–6 ··· X, where X=H2 and H2O. The calculated binding energies were corrected for the basis set superposition error (BSSE). The structural parameters and chemical hardness were calculated for the complexes of zinc oxide clusters and guest molecules. The strength values of the interaction between the clusters and the guest molecules were analyzed based on the topological properties of atoms in molecules (AIM) theory of Bade r. The stereo electronic interact ions inside the ZnO clusters were analyzed in detail using the natural bond orbital (NBO) analysis.     

Blue light emission of porous silicon subjected to RTP treatments

Porous silicon samples were treated with the rapid thermal process (RTP) under different circumstances (N2, Ar, O2 and Air). Before and after treatments, the samples were checked by means of photoluminescence (PL) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Four blue light emission peaks were found in the PL spectra of porous silicon samples subjected to the RTP treatments at temperatures above 400℃. The peak positions were found not to vary with the circumstances and temperatures of RTP treatments. It is considered that due to oxidation during the RTP treatments, the pole size of Si crystal in porous silicon decreased, resulting in the blue shift of light emission. Correlated with the Si crystal sizes discontinuous hypothesis and previous researchers' theory calculation, the PL peak positions did not vary with the RTP temperature and circumstances.     

Explicit solvent model for spectral shift of acrolein and simulation with molecular dynamics

By introducing the concept of spring energy of permanent dipole and taking the conforma-tions of solvent molecules into account,the formulas of electrostatic solvation energy in equilibrium and nonequilibrium are derived from the explicit solvent scheme,with the spatial distribution of the discrete permanent charges and induced dipoles of the sol-vent molecules involved. The energy change of sol-ute due to the variation of wave function from the case of vacuum to that in solution is estimated by treating the solvent effect as external field in the it-eration cycles of the self-consistent field. The ex-pression for spectral shift is deduced and applied to the processes of light absorption and emission in solution. According to the new formulations,the av-eraged solvent electrostatic potential/molecular dy-namics program is modified and adopted to investi-gate the equilibrium solvation energy of water mole-cule and spectral shift of acrolein.     

A Novel Calixarene-containing Hyperbranched Aliphatic Polyester Incorporated with Pendant Europium Complexes

1 Results Hyperbranched polymers can be easily functionalized,while the calixarene-rare earth complexes enjoy the advantages of narrow emission bands.It is expected that materials combining their advantages can possess good luminescence properties[1-2].For this reason,in this paper,a novel calixarene-containing hyperbranched aliphatic polyester incorporated with pendant europium complexes (H2O-Cal-Eu) was synthesized and characterized by FTIR,UV and element analysis.DSC measurement shows that the glass-transition temperature (Tg) of H2O-Cal-Eu is 127 ℃,which is higher than the Tg of H2O (30 ℃).TG measurement reveals that H2O-Cal-Eu has a good thermal stability,and there is no weight loss up to 280 ℃.The decomposition temperature (Td) of H2O-Cal-Eu is in the range of 280-500 ℃.The photoluminescence (PL) properties of H2O-Cal-Eu were investigated.As predicted,H2O-Cal was proved to be an excellent energy transfer ligand for Eu3 ,with respect to photoluminescence.H2O-Cal-Eu emitted remarkably strong red luminescence.The luminescence spectra of the solid samples of complex show a narrow half spectral bandwidth of only about 10 nm,which is nearly monochromatic light.Calixarene-containing polymer incorporated with pendant Eu (Ⅲ) complexes H2O-Cal-Eu exhibits great potential as red emitting materials for future generations of electroluminescence devices.     

利用分子束和激光技术研究电子激发态原子、分子的态-态传能(II)--亚稳态原子传能和激发态分子内能量传递

The article presents mainly the study of the changes of rotational angular momentum, electronic spin and nuclear spin in the collision of NH 2() with molecules and the channels of producing the excited NO in the collision of CO(a 3∏) with NO. The mechanism on the E-E energy transfer between rare gas metastable atoms and molecules is also discussed. In addition, the quantum state change in the excited molecules is also considered in the collision with or without intramolecular perturbation.     

NMR and FT-IR analysis of new molecular complex 1-piperidine-carboxylate-piperidinium-H2O

Piperidine absorbs CO2 and H2O contents in air to form a molecular complex： piperidium-1-piperidinecarboxylate-H2O. The structure of the complex was characterized by FT-IR and NMR. The complex is stabilized via five hydrogen bonds between the three components, N…O electrostatic interaction and O…O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Through electron transfer from the carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of free water molecule. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

Theoretical study on stereodynamics of H + NeH+ (v = 0, j = 0) → H2 + + Ne reaction

Stereodynamics of reaction H + NeH+(v = 0,j = 0) → H2+ + Ne is investigated by quasi-classical trajectory method using a new potential energy surface constructed by Lv et al.The distributions of P(r),P(r) and PDDCSs are calculated at four different collision energies.The rotational polarization of product H2+ presents different characters at different collision energies.The product rotational angular momentum vector j’ is not only aligned,but also oriented along the direction perpendicular to the scattering plane.With the increase of collision energy,the rotation of product molecule has a preference of changing from the "in-plane" mechanism to the "out-of-plane" mechanism.Although the title reaction is mainly dominated by the direct reaction mechanism,the indirect mechanism plays a role when the collision energies are low.     

Energy savings and CO2 emission reduction by using geothermal heat pumps

The renewable energy will play significant role in the world primary energy consumption in the future. Geothermal energy is immense with 5000 EJ/yr of technical potential; however, its utilization has been limited to areas with special geological conditions. Geothermal heat pumps (GHPs) are one of the fastest growing applications of renewable energy in the world with annual increases of 10% and much faster in China. Its main advantage is that it uses normal ground or groundwater temperatures (between about 5 and 30℃), which are available in all countries of the world and make geothermal more attractive and practicable. With high Coefficient of Performance (COP) up to 6, GHPs make efficiency of primary energy more than 240% with assumed a 40% of electricity generation efficiency, which means energy savings and CO2 emission reduction. In this paper geothermal and GHP technology is introduced and the energy savings and CO2 emission reduction by GHPs are analyzed.     

Energy transfer process between Eu3+ and wide-band-gap SnO2 nanocrystals in silica films studied by photoluminescence excitation and time-resolved photoluminescence techniques

Eu3+ions embedded in silica thin films codoped with SnO2 nanocrystals were fabricated by sol–gel and spin-coating methods.SnO2 nanocrystals with controllable sizes were synthesized through precisely controlling the Sn concentrations.The influences of doping and annealing conditions on the photoluminescence intensity from SnO2 nanocrystals are systematically investigated.The effective energy transfer from the defect states of SnO2nanocrystals to nearby Eu3+ions has revealed by the selective photoluminescence excitation spectra.The efficiency of the Forster resonance energy transfer is evaluated by the time-resolved photoluminescence measurements,which is about 29.1%based on the lifetime tests of the SnO2emission.     

Heterogeneity of water in UHP eclogites from Bixiling in Dabieshan： Evidence fromgarnet

Garnets in ultrahigh pressure (UHP) eclogites from Bixiling in Dabieshan were investigated by Fourier transform infrared spectrometer (FTIR). The results demonstrate that all garnets contain structural water which occurs as hydroxyl (OH), with contents ranging from 164 to 2034 ppm (H2O wt.) and mostly higher than 500 ppm. Like omphacite which is another major OH-rich mineral in eclogites, garnet is an important carrier that can recycle the surface water into deep mantles. Heterogeneity of water in garnets exists not only among different samples of the same outcrop (～150 m), but also among different crystals of the same sample (～1 cm). This indicates that the mobility of fluids during UHP metamorphism is very limited (possibly on centimeter scales), and that both subduction and exhumation processes of UHP rocks are very fast.     

Up-conversion luminescence of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4

The synthesis and up-conversion luminescent properties of YTaO4：Er^3＋ and YTaO4：Er^3＋/Yb^3＋ are reported for the first time. According to the measurement results of up-conversion spectra, Yb^3＋ co-doping can remarkably enhance the green （^2H11/2/^4S3/2→^4I15/2） and red （^4F9/2→^4I15/2） emissions, but depress the infrared emission （^4I9/2→^4I15/2）. With the increase of the Yb^3＋ concentration, the intensity of green emission increases, after that, when the Yb^3＋ concentration increases continuously, the intensity of green emission decreases, while those of the red and infrared emissions increase and decrease alternately. In addition, the up-conversion mechanisms of Er^3＋ doped and Er^3＋/Yb^3＋ co-doped YTaO4 are also discussed. It is found that the transform of up-conversion mechanism from two-step energy transfer to cooperating sensitization takes place when Yb^3＋ concentration is increased up to 12 mol%. With the further increase of Yb^3＋ concentration, the energy-back-transfer gradually becomes the dominant up-conversion mechanism, which results in the quenching of the green emission and slight increasing of the red and infrared emissions.     

E-E energy transfer rate for the reaction of N_2(a~1Π_g)+CO(X~1∑)→CO(A~1Π)+N_2(X~1∑_g)

The metastable N_2(a~1 Π_g, v~′) is not only one of the most important energy carriers in the discharge of nitrogen, but also one of the most prominent ultraviolet molecular emission source in the ionosphere. Knowledge of its energy transfer processes is important for chemical lasers, atmosphere chemistry and remote sensing applications. In 1972, Golde and     

Synthesis and formation mechanism of micro/nano flower-like MgCO3·5H2O

Micro/nano magnesium carbonate pentahydrate（MgCO3 ·5H2 O） with flower-like morphology was synthesized using magnesite as a substrate and potassium dihydrogen phosphate as an additive. The synthesized samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The influence of pyrolysis time on crystal morphology was explored. The formation mechanism was investigated on the basis of the characterized results and the crystal structure of MgCO3 ·5H2 O. The results showed that the flower-like MgCO3 ·5H2 O was 1.5-3.0 μm in length and 100-500 nm in diameter and was successfully obtained with a pyrolysis time of 30 min. The formation mechanism of flower-like MgCO3 ·5H2 O is suggested to be the selective adsorption of potassium dihydrogen phosphate on the surface. The process of flower-like crystal growth is as follows： amorphous nanoparticles formation, acicular and rod monocrystal formation, flower-like monocrystal formation, and flower-like polymers（MgCO3 ·5H2 O） crystallization. In the MgCO3 ·5H2 O crystal, the magnesium ion presents two different octahedral coordinations corresponding to2 26 Mg（H O）＋and2 2 2 4 23 [Mg（H O）（CO） ]--, and the chemical formula of the crystal is2 2 6 2 4 23 Mg（H O） Mg（H O）（CO）2.     

Synthesis and Property Studies of Transparent Resins Containing Rare Earth Complex Eu(Ⅲ) (TTA)_2(MA)_2 Phen·H_2O

A new rare earth complex Eu(Ⅲ)(TTA)2(MA)2Phen·H2O was synthesized and characterized by element analysis, FTIR, UV, thermal analysis, and fluorescence spectra. The strong fluorescence and high thermal stability of Eu(Ⅲ)(TTA)2(MA)2Phen·H2O were used to modify resin. The copolymer containing europium was prepared by copolymerization of Eu(Ⅲ) and styrene/α-methylacrylic acid, and characterized by FTIR and fluorescence spectra. The fluorescence spectra showed that the copolymer was a sort of materials with good ...     

Influences of the degradation of swamp and alpine meadows on CO2 emission during growing season on the Qinghai-Tibet Plateau

CO2 emission fluxes of two types of ecosystem, swamp meadow and alpine meadow, in the Fenghuo- shan region of the Qinghai-Tibet Plateau were studied by the static chamber-portable infrared chro- matographic method. The results showed that there was large difference in the CO2 emission fluxes between the two ecosystems and in the same ecosystem of different degradation degrees. CO2 emis- sion flux of the swamp meadow gradually decreased with increasing degradation degree, while that of the alpine meadow gradually increased with increasing degradation degree except in May. The CO2 emission flux of undegraded swamp meadow was 65.1%―80.3% higher than that of undegraded alpine meadow; and the CO2 emission flux of moderately degraded swamp meadow was 22.1%―67.5% higher than that of alpine meadow; but the CO2 emission flux of severely degraded alpine meadow was 14.3%―29.5% higher than that of swamp meadow. The soil moisture content and temperature in the upper 5 cm soil layer and above-ground biomass were significantly correlated with the CO2 emission fluxes and regarded as the main environment factors to control the CO2 emission.     

Bioactivity analysis of the Ta (V) doped SiO2–CaO–Na2O–P2O5 ceramics prepared by solid state sintering method

The main objective of the study was to control the degradation rate of material at a higher degradation rate improving the chemical stability of the material. Ta is known to have good chemical resistance, biocompatibility and show no adverse biological response. In the present study, SiO2–Na2O–CaO–P2O5 bioceramics with different Ta2O5 contents was prepared by solid state sintering method at 1000 °C. The as-sintered ceramics were subjected to immersion studies in stimulated body fluid (SBF) for 21 days under static condition and characterized by XRD, FTIR, SEM, and AAS. The findings of the research indicate that the addition of Ta2O5 controlled degradability, and all samples showed sufficient bioactivity.     

The effect of hydrogen-bond in alcoholic solvent on the solvation ultrafast dynamics of oxazine 750 dye

The ultrafast dynamics of oxazine 750 dye was studied in methanol, ethanol, 1-propanol, 1-butanol solvents using the femtosecond time-resolved stimulated emission pumping fluorescence depletion （FS TR SEP FD） technique. The faster decays on the hundreds of femtosecond time scale and the slower decays on the order of picosecond were found. The intramolecular vibrational redistribution （IVR） and the solute-solvent intermolecular photoinduced electron transfer （ET） should account for the faster decay, while the slower decay is attributable to the diffusive solvent relaxation. The results show that the intermolecular hydrogen-bonding network will hinder the rearrangement of the alcoholic molecules in the solvaUon process and the time constants of the slower diffusive solvent relaxation decays are found to increase with the hydrogen-bonding energy in alcoholic solvents.     

Facile cathodic electrosynthesis and characterization of iron oxide nano-particles

Fe2O3 nano-particles have been synthesized by simple cathodic electrodeposition from the low-temperature nitrate bath.The morphology and crystal structure of the obtained oxide powder were analyzed by means of scanning and transmission microscopy(SEM and TEM),X-ray diffraction(XRD) and Fourier transform infrared(FTIR) spectroscopy.Thermal behavior and phase transformation during the heat treatment of as-deposited sample were investigated by differential scanning calorimetry(DSC) and thermogramimetric analysis(TGA).The results showed that the deposited Fe2O3 was composed of the nanoparticles with grain size of approximately 10-60 nm.A serious problem during cathodic electrodeposition of iron oxide was splashing of deposit into electrolyte due to its low adhesion.This problem was tackled by reducing the bath temperature and dielectric constant of solvent.