As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN thr...As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN through depth profiling using 405-,532-,and 638-nm wavelength lasers.The Raman signal intensity of the sapphire substrate at different focal depths is studied to analyze the depth resolution.Based on the shift of the E2 H mode of the GaN epitaxial layer,the interfacial stress for different types of GaN is characterized and calculated.The results show that the maximum interfacial stress appears approximately at the junction of the GaN and the sapphire substrate.Local interfacial stress analysis between the GaN epitaxial layer and the substrate will be very helpful in furthering the applications of GaN devices.展开更多
Confocal Raman microspectroscopy(CRM)is an important tool for analyzing the compositional distribution of cell walls in situ.In this study,we improved the sample preparation method using paraffin-embedded sections com...Confocal Raman microspectroscopy(CRM)is an important tool for analyzing the compositional distribution of cell walls in situ.In this study,we improved the sample preparation method using paraffin-embedded sections combined with hexane dewaxing to obtain high resolution Raman images.We determined that the cell wall components of fiber cells were different from those of ray cells and vessel cells in the xylem of Populus tomentosa.Acetyl bromide and CRM methods produced similar trends when the difference in lignin intensity in the xylem region was compared between transgenic PtrLac4 and wild-type P.tomentosa.However,CRM proved more useful to analyze the lignin distribution in each cell type and distinguished the detailed difference in lignin intensity at the cellular level.Thus,CRM proved to be a useful in situ method to rapidly analyze the spatial variation of lignin content in the xylem of woody plants.展开更多
The understanding of the structure morphology of oil-rich emulsion from enzyme-assisted extraction processing(EAEP)was a critical step to break the oil-rich emulsion structure in order to recover oil.Albeit EAEP metho...The understanding of the structure morphology of oil-rich emulsion from enzyme-assisted extraction processing(EAEP)was a critical step to break the oil-rich emulsion structure in order to recover oil.Albeit EAEP method has been applied as an alternative way to conventional solvent extraction method,the structure morphology of oil-rich emulsion was still unclear.The current study aimed to investigate the structure morphology of oil-rich emulsion from EAEP using 3 D confocal Raman imaging technique.With increasing the enzymatic hydrolysis duration from 1 to 3 h,the stability of oil-rich emulsion was decreased as visualized in the 3 D confocal Raman images that the protein and oil were mixed together.The subsequent Raman spectrum analysis further revealed that the decreased stability of oil-rich emulsion was due to the protein aggregations via SS bonds or protein-lipid interactions.The conformational transfer in protein indicated the formation of a compact structure.展开更多
Non-destructive stress characterization is essential for gate-all-around(GAA)nanosheet(NS)transistors technology,while it is a big challenge to be realized on nanometer-sized GAA devices by using traditional Micro-Ram...Non-destructive stress characterization is essential for gate-all-around(GAA)nanosheet(NS)transistors technology,while it is a big challenge to be realized on nanometer-sized GAA devices by using traditional Micro-Raman spectroscopy due to its light spot far exceeding the device.In this work,a non-destructive stress characterization methodology of confocal Raman spectroscopy was proposed and performed for GAANS device fabrication.Channel stress evolution along the fabrication process was successfully characterized by designing high-density NS array and analyzing the linear scanned spectra in different structures.The related mechanism of stress evolution was systematically studied by Sentaurus process simulation.Additionally,applying this methodology on detecting the bending of suspended NS after channel release process was demonstrated.Therefore,this work might provide a promising solution to realize in-line characterization of channel stress in GAA NS transistors and process monitor of NS channel integrity.展开更多
Surface enhanced Raman spectroscopy(SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particle...Surface enhanced Raman spectroscopy(SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particles produced by spray flash evaporation(SFE). Morphology, size and crystallinity of furosemide/PVP particles are analyzed by scanning electron microscopy(SEM) and X-ray powder diffraction(XRPD). Far-field Raman spectra and confocal far-field Raman maps of furosemide/PVP particles are interpreted based on the far-field Raman spectra of pure furosemide and PVP precursors.Confocal far-field Raman microscopy shows that furosemide/PVP particles feature an intermixture of furosemide and PVP molecules at the sub-micron scale. SERS and surface-enhanced confocal Raman microscopy(SECo RM) are performed on furosemide, PVP and furosemide/PVP composite particles sputtered with silver(40 nm). SERS and SECo RM maps reveal that furosemide/PVP particle surfaces mainly consist of PVP molecules. The combination of surface and bulk sensitive analyses reveal that furosemide/PVP sub-micron particles are formed by the agglomeration of primary furosemide nanocrystals embedded in a thin PVP matrix. Interestingly, both far-field Raman microscopy and SECo RM provide molecular information on a statistically-relevant amount of sub-micron particles in a single microscopic map;this combination is thus an effective and time-saving tool for investigating organic sub-micron composites.展开更多
Deliquescence and efflorescence are the two most important physicochemical processes of aerosol particles. In deliquescence and efflorescence cycles of aerosol particles, many fundamental problems need to be investiga...Deliquescence and efflorescence are the two most important physicochemical processes of aerosol particles. In deliquescence and efflorescence cycles of aerosol particles, many fundamental problems need to be investigated in detail on the molecular level, including ion and molecule interactions in supersaturated aerosols, metastable solid phases that may be formed, and microscopic structures and deliquescence mechanisms of aerosol particles. This paper presents a summary of the progress made in recent investigations of deliquescence and efflorescence processes of aerosol particles by four common spectral techniques, which are known as Raman/electrodynamic balance, Fourier transform infrared/aerosol flow tube, Fourier transform infrared/attenuated total reftection, and confocal Raman on a quartz substrate.展开更多
As a single photon source,silicon vacancy(V_(Si))centers in wide bandgap semiconductor silicon carbide(SiC)are expected to be used in quantum technology as spin qubits to participate in quantum sensing and quantum com...As a single photon source,silicon vacancy(V_(Si))centers in wide bandgap semiconductor silicon carbide(SiC)are expected to be used in quantum technology as spin qubits to participate in quantum sensing and quantum computing.Simultaneously,the new direct femtosecond(fs)laser writing technology has been successfully applied to preparing V_(Si)s in SiC.In this study,6H-SiC,which has been less studied,was used as the processed material.V_(Si) center arrays were formed on the 6H-SiC surface using a 1030-nm-wavelength fs pulsed laser.The surface was characterized by white light microscopy,atomic force microscopy,and confocal photoluminescence(PL)/Raman spectrometry.The effect of fs laser energy,vector polarization,pulse number,and repetition rate on 6H-SiC V_(Si) defect preparation was analyzed by measuring the V_(Si) PL signal at 785-nm laser excitation.The results show that fs laser energy and pulse number greatly influence the preparation of the color center,which plays a key role in optimizing the yield of V_(Si)s prepared by fs laser nanomachining.展开更多
基金the National Natural Science Foundation of China(Grant Nos.51575389 and 51761135106)the National Key Research and Development Program of China(Grant No.2016YFB1102203)+1 种基金the State Key Laboratory of Precision Measuring Technology and Instruments(Pilt1705)the‘111’Project of the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN through depth profiling using 405-,532-,and 638-nm wavelength lasers.The Raman signal intensity of the sapphire substrate at different focal depths is studied to analyze the depth resolution.Based on the shift of the E2 H mode of the GaN epitaxial layer,the interfacial stress for different types of GaN is characterized and calculated.The results show that the maximum interfacial stress appears approximately at the junction of the GaN and the sapphire substrate.Local interfacial stress analysis between the GaN epitaxial layer and the substrate will be very helpful in furthering the applications of GaN devices.
基金funded by the Fundamental Research Funds for the Central Universities(Grant No.2019ZY30)National Natural Science Foundation of China(Grant No.31971618,Grant No.31570582)。
文摘Confocal Raman microspectroscopy(CRM)is an important tool for analyzing the compositional distribution of cell walls in situ.In this study,we improved the sample preparation method using paraffin-embedded sections combined with hexane dewaxing to obtain high resolution Raman images.We determined that the cell wall components of fiber cells were different from those of ray cells and vessel cells in the xylem of Populus tomentosa.Acetyl bromide and CRM methods produced similar trends when the difference in lignin intensity in the xylem region was compared between transgenic PtrLac4 and wild-type P.tomentosa.However,CRM proved more useful to analyze the lignin distribution in each cell type and distinguished the detailed difference in lignin intensity at the cellular level.Thus,CRM proved to be a useful in situ method to rapidly analyze the spatial variation of lignin content in the xylem of woody plants.
基金the financial support received from National Natural Science Foundation of China(No.31430067 and 31601475)China Postdoctoral Science Foundation funded project(No.2017M610200)Heilongjiang Postdoctoral Foundation(No.LBH-Z17011)
文摘The understanding of the structure morphology of oil-rich emulsion from enzyme-assisted extraction processing(EAEP)was a critical step to break the oil-rich emulsion structure in order to recover oil.Albeit EAEP method has been applied as an alternative way to conventional solvent extraction method,the structure morphology of oil-rich emulsion was still unclear.The current study aimed to investigate the structure morphology of oil-rich emulsion from EAEP using 3 D confocal Raman imaging technique.With increasing the enzymatic hydrolysis duration from 1 to 3 h,the stability of oil-rich emulsion was decreased as visualized in the 3 D confocal Raman images that the protein and oil were mixed together.The subsequent Raman spectrum analysis further revealed that the decreased stability of oil-rich emulsion was due to the protein aggregations via SS bonds or protein-lipid interactions.The conformational transfer in protein indicated the formation of a compact structure.
基金supported by the platform for the development of next generation integration circuit technology.
文摘Non-destructive stress characterization is essential for gate-all-around(GAA)nanosheet(NS)transistors technology,while it is a big challenge to be realized on nanometer-sized GAA devices by using traditional Micro-Raman spectroscopy due to its light spot far exceeding the device.In this work,a non-destructive stress characterization methodology of confocal Raman spectroscopy was proposed and performed for GAANS device fabrication.Channel stress evolution along the fabrication process was successfully characterized by designing high-density NS array and analyzing the linear scanned spectra in different structures.The related mechanism of stress evolution was systematically studied by Sentaurus process simulation.Additionally,applying this methodology on detecting the bending of suspended NS after channel release process was demonstrated.Therefore,this work might provide a promising solution to realize in-line characterization of channel stress in GAA NS transistors and process monitor of NS channel integrity.
文摘Surface enhanced Raman spectroscopy(SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particles produced by spray flash evaporation(SFE). Morphology, size and crystallinity of furosemide/PVP particles are analyzed by scanning electron microscopy(SEM) and X-ray powder diffraction(XRPD). Far-field Raman spectra and confocal far-field Raman maps of furosemide/PVP particles are interpreted based on the far-field Raman spectra of pure furosemide and PVP precursors.Confocal far-field Raman microscopy shows that furosemide/PVP particles feature an intermixture of furosemide and PVP molecules at the sub-micron scale. SERS and surface-enhanced confocal Raman microscopy(SECo RM) are performed on furosemide, PVP and furosemide/PVP composite particles sputtered with silver(40 nm). SERS and SECo RM maps reveal that furosemide/PVP particle surfaces mainly consist of PVP molecules. The combination of surface and bulk sensitive analyses reveal that furosemide/PVP sub-micron particles are formed by the agglomeration of primary furosemide nanocrystals embedded in a thin PVP matrix. Interestingly, both far-field Raman microscopy and SECo RM provide molecular information on a statistically-relevant amount of sub-micron particles in a single microscopic map;this combination is thus an effective and time-saving tool for investigating organic sub-micron composites.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20073004, No.20473012, No.20673010, and No.20640420450）, the 111 Project B07012, and the China Postdoctoral Science Foundation （No.20070410466）. The Trans-Century Training Program Foundation for the Talents by the Ministry of Education of China was also gratefully acknowledged.
文摘Deliquescence and efflorescence are the two most important physicochemical processes of aerosol particles. In deliquescence and efflorescence cycles of aerosol particles, many fundamental problems need to be investigated in detail on the molecular level, including ion and molecule interactions in supersaturated aerosols, metastable solid phases that may be formed, and microscopic structures and deliquescence mechanisms of aerosol particles. This paper presents a summary of the progress made in recent investigations of deliquescence and efflorescence processes of aerosol particles by four common spectral techniques, which are known as Raman/electrodynamic balance, Fourier transform infrared/aerosol flow tube, Fourier transform infrared/attenuated total reftection, and confocal Raman on a quartz substrate.
基金supported by the‘111’project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘As a single photon source,silicon vacancy(V_(Si))centers in wide bandgap semiconductor silicon carbide(SiC)are expected to be used in quantum technology as spin qubits to participate in quantum sensing and quantum computing.Simultaneously,the new direct femtosecond(fs)laser writing technology has been successfully applied to preparing V_(Si)s in SiC.In this study,6H-SiC,which has been less studied,was used as the processed material.V_(Si) center arrays were formed on the 6H-SiC surface using a 1030-nm-wavelength fs pulsed laser.The surface was characterized by white light microscopy,atomic force microscopy,and confocal photoluminescence(PL)/Raman spectrometry.The effect of fs laser energy,vector polarization,pulse number,and repetition rate on 6H-SiC V_(Si) defect preparation was analyzed by measuring the V_(Si) PL signal at 785-nm laser excitation.The results show that fs laser energy and pulse number greatly influence the preparation of the color center,which plays a key role in optimizing the yield of V_(Si)s prepared by fs laser nanomachining.
