Structure and Two-dimensional Correlation Infrared Spectroscopy Study of a New One-dimensional Chain Compound: (4,4’-Hbpy)_3[NaMo_8O_(26)](4,4’- bpy)_2(H_2O)_4 (bpy = Bipydine)

A novel compound, （4,4＇-Hbpy）3[NaMo8O26]（4,4＇-bpy）2（H2O）4 1 （bpy=bipydine）, was synthesized by the hydrothermal method. Single-crystal X-ray diffraction shows that compound 1 belongs to the monoclinic system, space group C2/m with a=19.1921（5）, b=18.6931（6）, c=9.3821（3） A° β=104.8020（11）°, V=3254.22（17）A°^3 C50H51Mo8N10NaO30, Mr=2062.52, Z=2, F（000）=2016, μ=1.591 mm^-1 and Dc=2.105 g/cm^3. The final R=0.0283 and wR=0.0912 for 3118 observed reflections （I〉20（I））. Compound 1 contains the β-[Mo8O26]^4-anion, sodium ion, 4,4＇-bpy and lattice crystalline water molecules. The β-[MosO26] units link the sodium ion to form a chain structure. The infinitechains of [Na（Mo8O26）]^3- blocks are surrounded by protonized 4,4＇-bpy cations, 4,4＇-bpy and lattice crystalline water molecules. The 2D-IR correlation spectroscopy study indicates that the stretching vibrations of Mo=O occur more preferentially due to the thermal effect. The TGA analysis shows that compound 1 has high thermal stability.

Evolution of Two-Dimensional Correlation Spectroscopy

A number of useful techniques associated with two-dimensional correlation spectroscopy(2DCOS)to improve its performance and utility have been developed in the last 30years.Evolution of these 2DCOS techniques,including some of the very recent developments,is reviewed with examples.Topics include merged or modified asynchronous 2Dcorrelation spectrum,two-dimensional codistribution spectroscopy(2DCDS),Pareto scaling,and null-space projection treatment of spectral dataset.

Review of Raman spectroscopy of two-dimensional magnetic van der Waals materials

Ultrathin van der Waals(vdW)magnets provide a possibility to access magnetic ordering in the two-dimensional(2D)limit,which are expected to be applied in the spintronic devices.Raman spectroscopy is a powerful characterization method to investigate the spin-related properties in 2D vdW magnets,including magnon and spin–lattice interaction,which are hardly accessible by other optical methods.In this paper,the recent progress of various magnetic properties in 2D vdW magnets studied by Raman spectroscopy is reviewed,including the magnetic transition,spin-wave,spin–lattice interaction,symmetry tuning induced by spin ordering,and nonreciprocal magneto-phonon Raman scattering.

USING TWO-DIMENSIONAL TIME RESOLVED LIGHT SCATTERING TO STUDY THE CURE REACTION INDUCED PHASE SEPARATION PROCESS OF EPOXY-AMINE-POLYETHERSULFONE BLEND WITH SECONDARY PHASE SEPARATION

The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns （2D TRLS） has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. （i） During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. （ii） The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. （iii） During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.

Two-dimension fluorescence correlation spectroscopy to characterize the binding of organic ligands with zinc in eutrophic lake

Metal binding of organic ligands can definitely affect its environmental behavior in waters,while information on the binding heterogeneity with different organic ligands is still lacked till now.In this study,the binding of zinc with organic matters associated with cyanobacterial blooms,including dissolved organic matters（DOM） and attached organic matters（AOM）,were studied by using fluorescence quenching titration combined with two-dimensional correlation spectroscopy（2D-COS）.Metal-induced fluorescent quenching was obviously observed both for DOM and AOM,indicating the formation of metal-ligand complexes.Compared with the one-dimensional spectra,2D-COS revealed the sequences of metal-ligand interaction with the following orders：276 nm 〉 232 ran for DOM and232 nm 〉 276 nm for AOM.Furthermore,the modified Stern-Volmer model showed that the binding constant（logKM） of 276 nm in DOM was higher than that of 232 nm（4.93 vs.4.51）,while AOM was characterized with a high binding affinity for 232 nm（log KM：4.83）.The ranks of log KM values were consistent with the sequential orders derived from 2D-COS results both for the two samples.Fluorescence quenching titration combined with 2D-COS was an effective method to characterize the metal-ligand interaction.

高圣草素-7-O-β-D-芹糖基(1→2)-β-D-葡萄糖苷与血清白蛋白相互作用研究

在模拟人体生理条件下,应用紫外吸收光谱、荧光光谱和同步荧光光谱法研究高圣草素-7-O-β-D-芹糖基(1→2)-β-D-葡萄糖苷(HAG)与牛血清白蛋白(BSA)及人血清白蛋白(HSA)的结合作用。结果表明:HAG对BSA和HSA的内源荧光均有显著的猝灭作用,且猝灭机理主要为静态猝灭。HAG与BSA和HSA的结合常数K分别为3.03×104L.mol-1和6.22×104L.mol-1,结合位点数n分别为0.858和0.911,结合距离r分别为2.88 nm和3.09 nm,其作用力以氢键和范德华力为主。利用同步荧光技术考察了HAG对BSA和HSA构象的影响。

Atomscopic of ripple origins for two-dimensional monolayer transition metal dichalcogenides

During the development of ultrathin two-dimensional(2D)materials,the appearance of ripples has been widely observed.However,the formation mechanisms and their influences are still rarely investigated,especially their contributions to the electronic structures and optical properties.To compensate for the knowledge gap,we have carried out comprehensive theoretical studies on the monolayer WSe_(2) with a series of ripple structures from 0 to 12Åin different lattice sizes.The sensitivity of the formation energy,band structures,electronic structures,and optical properties to the ripple structures have been performed systematically for the first time.The formation of ripples in Armchair and zigzag simultaneously are more energetically favorable,leading to more flexible optimizations of the optoelectronic properties.The improved charge-locking effect and extension of absorption ranges indicate the significant role of ripple structures.The spontaneous formation of ripples is associated with orbital rearrangements and structural distortions.This leads to the unique charge carrier correlate inversion between W-5d and Se-4p orbitals,resulting in the pinning of the Fermi level.This work has supplied significant references to understand ultrathin 2D structures and benefit their future developments and applications in high-performance optoelectronic devices.

Generalized two-dimensional correlation near-infrared spectroscopy and principal component analysis of the structures of methanol and ethanol

Liquid state methanol and ethanol under different temperatures have been investigated by FT-NIR(Fourier transform nearinfrared) spectroscopy,generalized two-dimensional(2D) correlation spectroscopy,and PCA(principal component analysis) . First,the FT-NIR spectra were measured over a temperature range of 30-64(or 30-71) °C,and then the 2D correlation spectra were computed.Combining near-infrared spectroscopy,generalized 2D correlation spectroscopy,and references,we analyzed the molecular structures(especially the hydrogen bond) of methanol and ethanol,and performed the NIR band assignments. The PCA method was employed to verify the results of the 2D analysis.This study will be helpful to the understanding of these reagents.

Two-dimensional correlation spectroscopic studies on coordination between carbonyl group of butanone and metal ions

Two dimensional asynchronous spectra were used to characterize coordination between carbonyl group of butanone and metal ions by using an approach proposed in our recent paper.Spectral variation of n-π^＊transition band of carbonyl group is used to probe the coordination even if metal ions does not possess any characteristic peak in spectra.Experimental results indicate that Ca^2＋ and Al^3＋ show considerable ability to coordinate with the carbonyl group of butanone and bring about spectral variation of the n-π-＊transition band,which is manifested by cross peaks in 2D asynchronous spectra.

Application of 2D fluorescence correlation method to investigate the dilution-induced heterogeneous distribution of the bound FMN in azoreductase

AzoR is a homodimeric,flavin mononucleotide（FMN）-containing,NADH-dependent azoreductase from Escherichia coli.In this paper,we investigated the effect of the concentration of both AzoR and R59 G on the spectral behavior of the bound FMN using two-dimensional fluorescence correlation spectra.Two cross peaks（530,490） and（580,530） were observed from the dilution-induced 2D asynchronous correlation map of wt AzoR,while only one cross peak appeared at（600,530） for R59 C mutant.This result indicated that the mutation at site 59 influenced the formation of dilution-induced intermediates.The specific activity of both AzoR and R59 G mutant was unaffected by dilution when the enzyme concentration is below 1 μmol/L,which suggested that no significant dissociation of FMN occurred at low concentrations.Additionally,in order to explore the origin of these intermediates,we carried out a2 D correlation analysis using excitation wavelength-dependent fluorescence emission spectroscopy.The results showed that there coexisted two types of FMN that emitted fluorescence at 530 nm and 500 nm,respectively.Taken together,these results suggested that the 2D method is a very powerful method to identify the heterogeneous distribution of the bound FMN in solution.

pH-induced structural changes of surface immobilized poly (L-lysine) by two-dimensional (2D) infrared correlation study

This paper reports the pH-induced structural changes in the surface immobilized poly（L-lysine）（PLL）film.Two-dimensional（2D） correlation analysis was applied to the Fourier transform infrared（FTIR）spectra of the surface-immobilized PLL film to examine the spectral changes induced by the alternations of the protonation state of the amino group in the side chain.Significant spectral changes in the FTIR spectra of the PLL film were observed between pH 7 and 8.The decrease in the protonation state of the amino group in the side chain induced spectral changes in the amino group as well as conformational changes in the alky]group in the side chain.From pH 1-8,the spectral changes in the amino and alkyl groups in the side chain occurred before those of the amide group in the main chain of the surface immobilized PLL film.

Adsorption of arsenate on lanthanum-impregnated activated alumina:In situ ATR-FTIR and two-dimensional correlation analysis study

Lanthanum modified materials have been widely used for the removal of hazardous anions.In this study,in situ ATR-FTIR and two-dimensional correlation analysis were employed to investigate the adsorption mechanism of arsenate（As（V）） on lanthanum-impregnated activated alumina（LAA）.Our results showed that electrostatic interaction attracted As（V） anions to the LAA surface,and then As（V） could form monodentate configuration on the LAA surface at pH 5-9.The result of 2D-COS showed that two coexistent adsorbed As（V） species,H2AsO4^- and HAsO4^2-,were adsorbed on the LAA surface without specific sequence at different pH conditions,indicating a negligible role of the incorporated protons of As（V） on the adsorption affinity to LAA surface.The results of this study reveal insights into LAA surface complexes on the molecular scale and provide theoretical support to new metal oxides design for efficient arsenic removal.

含三(2-吡啶甲基)胺识别体的荧光化学敏感器核磁共振谱分析

采用二维核磁共振谱技术对新型丹磺酰胺和1,8_萘酰亚胺荧光化学敏感器的结构进行了测定。应用 1H - 1HCOSY、HSQC。

A Porous Organic-inorganic Hybrid Compound Constructed from Polyoxovanadium Borate Anions,Dinuclear Na Sites and Metal-organic Units

A polyoxovanadium borate [Na（H2O）]2[Na（H2O）2]2[Cu（en）2][V12B18O54（OH）6]·（H3O）2·（H2O）18 1（en = ethylenediamine） has been hydrothermally synthesized and characterized by IR,two-dimensional infrared（2D IR） correlation spectroscopy with magnetic and thermal perturba-tion,thermal IR spectroscopy,thermal gravimetric analysis and single-crystal X-ray diffraction.It crystallizes in triclinic,space group P with a = 12.981（3）,b = 13.044（3）,c = 14.208（3） ,α = 63.98（3）,β = 77.17（3）,γ = 14.208（3）°,V = 2001.0（8） 3,Z = 1,Mr = 2518.05,Dc = 2.090 g/cm-1,F（000） = 1255.0,Mu（mm-1） = 1.756,λ（MoKα） = 0.71073 ,R = 0.0625 and wR = 0.1952.In 1,the [V12B18O54（OH）6]8- units are connected by [Cu（en）2]2＋,binuclear Na（1） and Na（2） to form a three-dimensional porous framework.

Layer-dependent signatures for exciton dynamics in monolayer and multilayer WSe2 revealed by fluorescence lifetime imaging measurement

Two-dimensional(2D)transition-metal dichalcogenide(TMD)materials have aroused noticeable interest due to their distinguished electronic and optical properties.However,little is known about their complex exciton properties together with the exciton dynamics process which have been expected to influence the performance of optoelectronic devices.The process of fluorescence can well reveal the process of exciton transition after excitation.In this work,the room-temperature layer-dependent exciton dynamics properties in layered WSe2 are investigated by the fluorescence lifetime imaging microscopy(FLIM)for the first time.This paper focuses on two mainly kinds of excitons including the direct transition neutral excitons and trions.Compared with the lifetime of neutral excitons(<0.3 ns within four-layer),trions possess a longer lifetime(~6.6 ns within four-layer)which increases with the number of layers.We attribute the longer-lived lifetime to the increasing number of trions as well as the varieties of trion configurations in thicker WSe2.Besides,the whole average lifetime increases over 10%when WSe2 flakes added up from monolayer to four-layer.This paper provides a novel tuneable layer-dependent method to control the exciton dynamics process and finds a relatively longer transition lifetime of trions at room temperature,enabling to investigate in the charge transport in TMD-based optoelectronics devices in the future.

The exceedingly strong two-dimensional ferromagnetism in biatomic layer SrRuO_(3)with a critical conduction transition

In recent years,few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional(2D)magnets into next-generation spintronic devices.The SrRuO_(3)monolayer is a rare example of stable 2D magnetism under ambient conditions,but only weak ferromagnetism or antiferromagnetism has been found.The biatomic layer SrRuO_(3)as another environmentally inert 2D magnetic system has been paid less attention heretofore.Here we study both the bi-atomic layer and monolayer SrRuO_(3)in(SrRuO_(3))n/(SrTiO_(3))m(n=1,2)superlattices in which the SrTiO3 serves as a non-magnetic and insulating space layer.Although the monolayer exhibits arguably weak ferromagnetism,we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2μB/Ru,demonstrated by both superconducting quantum interference device(SQUID)magnetometry and element-specific X-ray circular dichroism.Moreover,in the bi-atomic layer SrRuO_(3),we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport,but are much less critical to the ferromagnetism.Our study demonstrates that the bi-atomic layer SrRuO_(3)is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.

Direct evidence of two-dimensional electron gas-like band structures in hafnene

Two-dimensional(2D)honeycomb-like materials have been widely studied due to their fascinating properties.In particular,2D honeycomb-like transition metal monolayers,which are good 2D ferromagnet candidates,have attracted intense research interest.The honeycomb-like structure of hafnium,hafnene,has been successfully fabricated on the Ir(111)substrate.However,its electronic structure has not yet been directly elucidated.Here,we report the electronic structure of hafnene grown on the Ir(111)substrate using angle-resolved photoemission spectroscopy(ARPES).Our results indicate that the presence of spin-orbit coupling and Hubbard interaction suppresses the earlier predicted Dirac cones at the K points of the Brillouin zone.The observed band structure of hafnene near the Fermi level is very simple:an electron pocket centered at theΓpoint of the Brillouin zone.This electron pocket shows typical parabolic dispersion,and its estimated electron effective mass and electron density are approximately 1.8_(me)and 7×10^(14)cm^(-2),respectively.Our results demonstrate the existence of 2D electron gas in hafnene grown on the Ir(111)substrate and therefore provide key information for potential hafnene-based device applications.

ATR-FTIR光谱技术在聚合物膜研究中的应用

红外光谱是聚合物研究中常用的一种表征手段,而衰减全反射红外光谱(ATR-FTIR)更是由于在研究聚合物薄膜方面具有显著的优势而被广泛使用。逐层组装(layer-by-layer assembly)技术是一种常用的组装聚合物超薄膜的方法,ATR-FTIR光谱技术的引入可以在获取膜组装过程中相应信息的同时有效地避免表征过程中对样品的损害。另一方面,ATR-FTIR方法与二维相关光谱技术(two-dimensional correlationspectroscopy,2D correlation spectroscopy)相结合也是研究小分子(主要是水分子)在聚合物薄膜中的渗透行为的有效手段。本文对ATR-FTIR的基本原理和显著特点作了介绍,并以实例阐述该方法在逐层组装技术和水分子在薄膜内渗透行为研究两方面的应用。

鱼粉、豆粕样本-样本二维相关近红外光谱判别

为了探讨利用二维相关近红外光谱法快速判别鱼粉和豆粕饲料原料的可行性,共收集了52个鱼粉、60个豆粕样品,其中34个鱼粉和40个豆粕样品作为定标集,其余18个鱼粉和20个豆粕样品作为独立验证集,用Spectrum400型近红外光谱仪扫描获取光谱,并对其特征峰进行解析。采用样本-样本二维相关分析方法定性判别鱼粉、豆粕,当预处理方法为一阶导数时,判断正确率为100%。与偏最小二乘判别分析方法相比,二者均可正确检测鱼粉、豆粕,其中二维相关方法的建模及验证算法简单、计算量小、运算速度快。

乙醇丙酮体系的广义二维相关近红外光谱分析

利用近红外及二维相关光谱进行了丙酮乙醇两种试剂体系的结构分析。首先检测30~50℃范围内（每隔2℃）的近红外光谱,结合近红外光谱、二维相关光谱及相关文献,对乙醇丙酮体系的分子结构（特别是氢键）进行了分析。近红外光谱的特征峰在一维图上变化不明显,借助于二维相关分析,提高了分辨率和可解释性。特别是分析了两种氢键羟基的存在,发现了烯醇羟基形成氢键及甲基与羰基形成氢键的证据,确定了不同分子结构之间的变化先后顺序,并进行了本体系近红外峰的归属。研究结果将有利于更深刻地理解该类试剂,为其进一步研究和使用提供参考。