In-situ/operando techniques to identify active sites for thermochemical conversion of CO_(2) over heterogeneous catalysts

The catalytic conversion of CO_(2) to fuels or chemicals is considered to be an effective pathway to mitigate the greenhouse effect. To develop new types of efficient and durable catalysts, it is critical to identify the catalytic active sites, surface intermediates, and reaction mechanisms to reveal the relationship between the active sites and catalytic performance. However, the structure of a heterogeneous catalyst usually dynamically changes during reaction, bringing a great challenge for the identification of catalytic active sites and reaction pathways. Therefore, in-situ/operando techniques have been employed to real-time monitor the dynamic evolution of the structure of active sites under actual reaction conditions to precisely build the structure–function relationship. Here, we review the recent progress in the application of various in-situ/operando techniques in identifying active sites for catalytic conversion of CO_(2) over heterogeneous catalysts. We systematically summarize the applications of various optical and X-ray spectroscopy techniques, including Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), in identifying active sites and determining reaction mechanisms of the CO_(2) thermochemical conversion with hydrogen and light alkanes over heterogeneous catalysts. Finally, we discuss challenges and opportunities for the development of in-situ characterization in the future to further enlarge the capability of these powerful techniques.

Applications of Raman spectroscopy in two-dimensional materials

At present,two-dimensional(2D)materials have shown great application potential in numerous fields based on their physical chemical and electronic properties.Raman spectroscopy and de-rivative techniques are effective tools for characterizing 2D materials.Raman spectroscopy conveys lots of knowledge on 2D materials,including layer number,doping type,strain and interlayer coupling.This review summarized advanced applications of Raman spectroscopy in 2D materials.The challenges and possible applied directions of Raman spectroscopy to 2D materials are discussed in detail.

An Initial Analysis of a Strongly Lensed QSO Candidate Identified by LAMOST

From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.

Overview of the LAMOST-Kepler project

The NASA Kepler mission obtained long-term high-quality photometric observations for a large number of stars in its original field of view from 2009 to 2013.To provide reliable stellar parameters in a homogeneous way,the LAMOST telescope began to carry out low-resolution spectroscopic observations for as many stars as possible in the Kepler field in 2012.By June 2018,238386 low-resolution spectra with SNRg≥6 had been collected for 155623 stars in the Kepler field,enabling the determination of atmospheric parameters and radial velocities,as well as spectral classification of the target stars.This information has been used by astronomers to carry out research in various fields,including stellar pulsations and asteroseismology,exoplanets,stellar magnetic activity and flares,peculiar stars and the Milky Way,binary stars,etc.We summarize the research progress in these fields where the usage of data from the LAMOST-Kepler(LK)project has played a role.In addition,time-domain medium-resolution spectroscopic observations have been carried out for about 12000 stars in four central plates of the Kepler field since 2018.The currently available results show that the LAMOST-Kepler medium resolution(LKMRS)observations provide qualified data suitable for research in additional science projects including binaries,high-amplitude pulsating stars,etc.As LAMOST is continuing to collect both low-and mediumresolution spectra of stars in the Kepler field,we expect more data to be released continuously and new scientific results to appear based on the LK project data.

Method of composing two-dimensional scanned spectra observed by the New Vacuum Solar Telescope

In this paper we illustrate the technique used by the New Vacuum Solar Telescope（NVST）to increase the spatial resolution of two-dimensional（2D）solar spectroscopy observations involving two dimensions of space and one of wavelength.Without an image stabilizer at the NVST,large scale wobble motion is present during the spatial scanning,whose instantaneous amplitude can reach 1.3′′due to the Earth’s atmosphere and the precision of the telescope guiding system,and seriously decreases the spatial resolution of 2D spatial maps composed with scanned spectra.We make the following effort to resolve this problem：the imaging system（e.g.,the Ti O-band）is used to record and detect the displacement vectors of solar image motion during the raster scan,in both the slit and scanning directions.The spectral data（e.g.,the Hαline）which are originally obtained in time sequence are corrected and re-arranged in space according to those displacement vectors.Raster scans are carried out in several active regions with different seeing conditions（two rasters are illustrated in this paper）.Given a certain spatial sampling and temporal resolution,the spatial resolution of the composed 2D map could be close to that of the slit-jaw image.The resulting quality after correction is quantitatively evaluated with two methods.A physical quantity,such as the line-of-sight velocities in multiple layers of the solar atmosphere,is also inferred from the re-arranged spectrum,demonstrating the advantage of this technique.

Capsella bursa-pastoris extract as an eco-friendly inhibitor on the corrosion of Q235 carbon steels in 1 mol·L^(-1) hydrochloric acid

The corrosion inhibition effect of Capsella bursa-pastoris extracts(CBE) for Q235 carbon steels in 1 mol·L-1hydrochloric acid solution was studied using electrochemical methods, environmental scanning electron microscopy(SEM) and Raman microscopy analysis. The polarization plots indicate that CBE serves as an effective, mixedtype inhibitor. Linear polarization resistance shows that increasing CBE concentration and temperature results in increased inhibition ef ficiency. The highest inhibition ef ficiency can reach 97% when adding 60 mg·L-1CBE,which is better than some reported plant extracts under the similar environment. The adsorption of CBE molecules is found to obey the Langmuir adsorption isotherm. Some thermodynamic and kinetic parameters for the adsorption process, such as the adsorption equilibrium constant(K), free energy of adsorption(ΔG ads), activation energy of corrosion reaction(E a) and the heat of adsorption(Q ads), are calculated and discussed. SEM and Raman microscopy analysis also demonstrate the formation of a CBE inhibition film on the metal surface.

Radial velocity measurements from LAMOST medium-resolution spectroscopic observations: a pointing towards the Kepler field

Radial velocity is one of the key measurements in understanding the fundamental properties of stars, stellar clusters and the Galaxy. A plate of stars in the Kepler field was observed in May of 2018 with the medium-resolution spectrographs of LAMOST, aiming to test the performance of this new system which is the upgraded equipment of LAMOST after the first five-year regular survey. We present our analysis on the radial velocity measurements(RVs) derived from these data. The results show that slight and significant systematic errors exist among the RVs obtained from the spectra collected by different spectrographs and exposures, respectively. After correcting the systematic errors with different techniques, the precision of RVs reaches ～1.3,～1.0,～0.5 and ～0.3 km s^(-1) at S/Nr = 10, 20, 50 and 100, respectively. Comparing with the RVs of standard stars from the APOGEE survey, our RVs are calibrated with a zero-point shift of～7 km s^(-1). The results indicate that the LAMOST medium-resolution spectroscopic system may provide RVs with a reasonable accuracy and precision for the selected targets.

Mapping of Compositional Diversity and Chronological Ages of Lunar Farside Multiring Mare Moscoviense Basin:Implications to the Middle Imbrian Mare Basalts

The Mare Moscoviense is an astonishing rare flatland multi-ring basin and one of the recognizable mare regions on the Moon's farside.The mineralogical,chronological,topographical and morphological studies of the maria surface of the Moon provide a primary understanding of the origin and evolution of the mare provinces.In this study,the Chandrayaan-1 M^(3)data have been employed to prepare optical maturity index,FeO and TiO^(2)concentration,and standard band ratio map to detect the mafic indexes like olivine and pyroxene minerals.The crater size frequency distribution method has been applied to LROC WAC data to obtain the absolute model ages of the Moscoviense basin.The four geological unit ages were observed as 3.57 Ga(U-2),3.65 Ga(U-1),3.8 Ga(U-3)and 3.92 Ga(U-4),which could have been formed between the Imbrian and Nectarian epochs.The M^(3)imaging and reflectance spectral parameters were used to reveal the minerals like pyroxene,olivine,ilmenite,plagioclase,orthopyroxene-olivine-spinel lithology,and olivine-pyroxene mixtures present in the gabbroic basalt,anorthositic and massive ilmenite rocks,and validated with the existing database.The results show that the Moscoviense basin is dominated by intermediate TiO^(2)basalts that derived from olivine-ilmenite-pyroxene cumulate depths ranging from 200 to 500 km between 3.5 Ga and 3.6 Ga.

Measuring fiber position errors from spectral data

Precise fiber positioning is crucial to a wide field, multi-fiber spectroscopic survey such as the Guoshoujing Telescope （the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST）. are based on CCD photographic and Nowadays, most position error measurements image processing techniques. These methods only work for measuring errors orthogonal to the telescope optical axis, but there are also errors that lie parallel to the optical axis of the telescope, such as defocusing, and errors caused by the existing deviation angle between the optical axes of a fiber and the telescope. Directly measuring the two latter types of position errors is difficult for an individual fiber, especially during observations. Possible sources of fiber position errors are discussed in brief for LAMOST. By constructing a model of magnitude loss due to the fiber position error for a point source, we propose an indirect method to calculate both the total and systematic position errors for each individual fiber from spectral data. Restrictions and applications of this method are also discussed.

Microstructures and speciation of radionuclides in natural environment studied by advanced spectroscopy and theoretical calculation

The environmental behavior of radionuclides is mainly dependent on their speciation and microstructures at solid particles.The speciation and microstructures of radionuclides at molecular level can be achieved from advanced spectroscopy techniques and theoretical calculations.In this perspective,we give a brief introduction of the advanced X-ray absorption fine structure(XAFS) technique and theoretical calculation in the analysis of the speciation and microstructures of radionuclides in the natural environment,which is crucial to evaluate the physicochemical behavior of radionuclides in the environment.

The coupling effect characterization for van der Waals structures based on transition metal dichalcogenides

van der Waals(vdW)heterostructures based on two-dimensional(2D)materials holding design-by-demand features offer astonishing opportunities to construct novel electronics and optoelectronics devices due to the vdW force interaction between their stacked components.At the atomically thin confinement,vdW heterostructure not only exhibits unprecedented properties as an entire counterpart,but also provides unique platforms to manipulate the vdW interfacial behaviors.Therefore,developing characterization techniques to comprehensively understand the coupling effect on structure-property-performance relationship of vdW heterostructures is crucial for fundamental science and practical applications.Here,we focus on the most widely studied 2D semiconductor transition metal dichalcogenides(TMDCs)and systematically review significant advances in characterizing the material and interfacial coupling effect of the related vdW heterostructures.Specially,we will discuss microscopy techniques for unveiling the structure-property relationship of vdW heterostructures and optical spectroscopy measurements for analyzing vdW interfacial coupling effect.Finally,we address some promising strategies to optimize characterization technologies for resolving vdW heterostructures,including coupling multiple characterization technologies,improving temporal and spatial resolution,developing fast,efficient,and non-destructive techniques and introducing artificial intelligence.