The exact electromagnetic enhancement mechanism behind SERS,TERS,HERS and SHINERS is one of the issues focused on in the study of enhanced Raman spectroscopy.The three dimensional finite difference time domain method(...The exact electromagnetic enhancement mechanism behind SERS,TERS,HERS and SHINERS is one of the issues focused on in the study of enhanced Raman spectroscopy.The three dimensional finite difference time domain method(3D-FDTD),which is widely used in nanoplasmonic simulations,not only provides us with a powerful numerical tool for theoretical studies of the ERS electromagnetic enhancement mechanism,but also serves as a useful tool for the design of ERS-active systems with higher sensitivities and spectral spatial resolution.In this paper,we first introduce the fundamental principles of FDTD algorithms,and then the size-dependent dielectric function of dispersive metallic material is discussed.A comparative study of FDTD and rigorous Mie evaluations of electromagnetic fields in the vicinity of a system of self-similar nanospheres shows an excellent correlation between the two computational methods,directly confirming the validity and accuracy of 3D-FDTD simulations in ERS calculations.Finally,we demonstrate,using a TERS calculation as an example,that the non-uniform mesh method can be more computationally efficient without loss of accuracy if it is applied correctly.展开更多
Tip-enhanced Raman spectroscopy （TERS） is high-sensitivity and high spatial-resolution optical analytical technique with nanoscale resolution beyond the diffraction limit. It is also one of the most recent advances ...Tip-enhanced Raman spectroscopy （TERS） is high-sensitivity and high spatial-resolution optical analytical technique with nanoscale resolution beyond the diffraction limit. It is also one of the most recent advances in nanoscale chemical analysis. This review provides an overview of the state-of-art inTERS, in-depth information about the different available types of instruments including their （dis）advantages and capabilities. Finally, an overview about recent development in High-Vacuum TERS is given and some challenges are raised.展开更多
By enabling the probing of light-matter interactions at the functionally relevant length scales of most materials, near-field optical imaging and spectroscopy accesses information that is unobtainable with other metho...By enabling the probing of light-matter interactions at the functionally relevant length scales of most materials, near-field optical imaging and spectroscopy accesses information that is unobtainable with other methods. The advent of apertureless techniques, which exploit the ultralocalized and enhanced near-fields created by sharp metallic tips or plasmonic nanoparticles, has resulted in rapid adoption of near-field approaches for studying novel materials and phenomena, with spatial resolution approaching sub-molecular levels. However, these approaches are generally limited by the dominant out-of-plane polarization response of apertureless tips, restricting the exploration and discovery of many material properties. This has led to recent design and fabrication breakthroughs in near-field tips engineered specifically for enhancing in-plane interactions with near-field light components. This mini-review provides a perspective on recent progress and emerging directions aimed at utilizing and controlling in-plane optical polarization, highlighting key application spaces where in-plane near-field tip responses have enabled recent advancements in the understanding and development of new nanostructured materials and devices.展开更多
In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure...In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure drop tmder varied inlet loadings. A laboratoryscale experimental biofilter for gaseous toluene removal was set up and operated for 100 days with inlet toluene concentration ranging from 250 to 2500 mg· m^-2 According to sensitivity analysis based on the model, the VOCs removal efficiency of the biofilter is more sensitive to Henry＇s constant, the specific surface area of the filter bed and the thickness of water layer, while the filter bed pressure drop is more sensitive to biomass yield coefficient and original void fraction. The calculated toluene removal efficiency and bed pressure drop satisfactorily fit the experimental data under varied inlet toluene loadings, which indicates the model in this study can be used to predict VOCs removal and bed pressure drop simultaneously. Based on the model, the effect of mass-transfer parameters on VOCs removal and the stable-run time of a biofilter are analyzed. The results demonstrate that the model can function as a good tool to evaluate the effect of biomass accumulation and optimize the design and operation of biofilters.展开更多
The interaction between a probing tip and an adsorbed molecule can significantly impact the molecular chemical structure and even induce its motion on the surface.In this study,the tip-induced bond weakening,tilting,a...The interaction between a probing tip and an adsorbed molecule can significantly impact the molecular chemical structure and even induce its motion on the surface.In this study,the tip-induced bond weakening,tilting,and hopping processes of a single molecule were investigated by sub-nanometre resolved tip-enhanced Raman spectroscopy(TERS).We used single carbon monoxide(CO)molecules adsorbed on the Cu(100)surface as a model system for the investigation.The vibrational frequency of the C−O stretching mode is always redshifted as the tip approaches,revealing the weakening of the C−O bond owing to tip−molecule interactions.Further analyses of both the vibrational Stark effect and TERS imaging patterns suggest a delicate tilting phenomenon of the adsorbed CO molecule on Cu(100),which eventually leads to lateral hopping of the molecule.While a tilting orientation is found toward the hollow site along the[110]direction of the Cu(100)surface,the hopping event is more likely to proceed via the bridge site to the nearest Cu neighbour along the[100]or[010]direction.Our results provide deep insights into the microscopic mechanisms of tip−molecule interactions and tip-induced molecular motions on surfaces at the single-bond level.展开更多
In order to study the effects of controlled release nitrogen fertilizer （CRNF） application on rapeseed, a simulated experiment was carried out with 3 types of paddy soils in Dongting Lake area for 4 consecutive year...In order to study the effects of controlled release nitrogen fertilizer （CRNF） application on rapeseed, a simulated experiment was carried out with 3 types of paddy soils in Dongting Lake area for 4 consecutive years of applying CRNF under double rice cropping system after planting rapeseed crop in the fallow season. The effects of CRNF application on rapeseed yield, agronomic characters and soil fertility were studied in this paper. The results showed that CRNF application improved the growth of rapeseed plant and increased rapeseed yield of CRNF treatments in the purple calcareous clayed paddy soil （PCS） and alluvial loamy paddy soil （ALS） which respectively increased by 12.2% and 9.8% compared with applying urea, re- spectively. The rapeseed yield in 70% CRNF treatment obviously decreased com- pared with urea treatment. The contents of available N and organic carbon in soil increased by 25.0% and 3.2% in CRNF treatment in the ALS after rapeseed crop, respectively; and available N increased by 13.5% in the PCS. Both rapeseed yield and soil fertility in CRNF treatment and 70% CRNF treatment were lower than those in CK treatment in the reddish yellow clayed paddy soil （RYS）. The results al- so indicated that the functions of CRNF application on rapeseed yield increase and soil nitrogen fertility improvement were very obvious in the PCS and ALS.展开更多
Based on conventional observation data, NCEP reanalysis data, wind profiler radar, Doppler radar, and satellite cloud image data, two times of severe convection weather in the west of Shandong Province during June 13-...Based on conventional observation data, NCEP reanalysis data, wind profiler radar, Doppler radar, and satellite cloud image data, two times of severe convection weather in the west of Shandong Province during June 13-14 in 2016 were analyzed. The results are shown as follows： firstly, the convection on the night of June 13 was stronger than that on the afternoon of June 14. The two times of severe convection weather generated under the circulation background of upper cold vortex. There was northwest air current at high altitudes and warm wet advection at low altitudes. Severe convection weather was triggered by low-level shear lines and surface convergence lines on June 13 and by weak cold air at 700 hPa on June 14 respectively. Secondly, there was certain water vapor transport and convergence before the occurrence of severe convection, and it was warm and wet at low altitudes but dry and cold at high altitudes; there was convergence at low altitudes and divergence at middle and high altitudes. 0 ℃ layer was at about 4 000 m, and-20 ℃ layer was at about 7 000 m. Thirdly, radar echo intensity was larger than 45 dBZ when severe convection happened, and it reached above 60 dBZ at an elevation of 1.5°, while middle strong echo zone overhung weak echo zone at low altitudes. Vertically integrated liquid（VIL） was up to 20 kg/m^2, and mesocyclone generated in strong echo zone; there was bow echo on the night of June 13, and VIL was higher than that on June 14. In wind profiler data, strong vertical wind shear and fluctuation of wind direction had denotative meaning to the occurrence of severe convection weather. Fourthly, hail, gale and other severe convection weather happened in front of long and narrow cold cloud zone and convective cloud clusters as well as in southwestern TBB gradient zone.展开更多
基金supported by the National Natural Science Foundation of China(20703032,10625418,10874233 and 10904171)the National Basic Research Program of China(2009CB930703,2006DFB02020 and 2009CB9-30700)+1 种基金the Natural Science Foundation of Fujian Province of China(E0710028)the Hundred Talents Project of Chinese Academy of Sciences
文摘The exact electromagnetic enhancement mechanism behind SERS,TERS,HERS and SHINERS is one of the issues focused on in the study of enhanced Raman spectroscopy.The three dimensional finite difference time domain method(3D-FDTD),which is widely used in nanoplasmonic simulations,not only provides us with a powerful numerical tool for theoretical studies of the ERS electromagnetic enhancement mechanism,but also serves as a useful tool for the design of ERS-active systems with higher sensitivities and spectral spatial resolution.In this paper,we first introduce the fundamental principles of FDTD algorithms,and then the size-dependent dielectric function of dispersive metallic material is discussed.A comparative study of FDTD and rigorous Mie evaluations of electromagnetic fields in the vicinity of a system of self-similar nanospheres shows an excellent correlation between the two computational methods,directly confirming the validity and accuracy of 3D-FDTD simulations in ERS calculations.Finally,we demonstrate,using a TERS calculation as an example,that the non-uniform mesh method can be more computationally efficient without loss of accuracy if it is applied correctly.
文摘Tip-enhanced Raman spectroscopy （TERS） is high-sensitivity and high spatial-resolution optical analytical technique with nanoscale resolution beyond the diffraction limit. It is also one of the most recent advances in nanoscale chemical analysis. This review provides an overview of the state-of-art inTERS, in-depth information about the different available types of instruments including their （dis）advantages and capabilities. Finally, an overview about recent development in High-Vacuum TERS is given and some challenges are raised.
文摘By enabling the probing of light-matter interactions at the functionally relevant length scales of most materials, near-field optical imaging and spectroscopy accesses information that is unobtainable with other methods. The advent of apertureless techniques, which exploit the ultralocalized and enhanced near-fields created by sharp metallic tips or plasmonic nanoparticles, has resulted in rapid adoption of near-field approaches for studying novel materials and phenomena, with spatial resolution approaching sub-molecular levels. However, these approaches are generally limited by the dominant out-of-plane polarization response of apertureless tips, restricting the exploration and discovery of many material properties. This has led to recent design and fabrication breakthroughs in near-field tips engineered specifically for enhancing in-plane interactions with near-field light components. This mini-review provides a perspective on recent progress and emerging directions aimed at utilizing and controlling in-plane optical polarization, highlighting key application spaces where in-plane near-field tip responses have enabled recent advancements in the understanding and development of new nanostructured materials and devices.
基金This research is supported by the National Natural Science Foundation of China （Grant No. 51378286） and special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control （No. 11Y04ESPCT）.
文摘In this study, a biofiltration model including the effect of biomass accumulation and inert biomass growth is developed to simultaneously predict the Volatile Organic Compounds （VOCs） removal and filter bed pressure drop tmder varied inlet loadings. A laboratoryscale experimental biofilter for gaseous toluene removal was set up and operated for 100 days with inlet toluene concentration ranging from 250 to 2500 mg· m^-2 According to sensitivity analysis based on the model, the VOCs removal efficiency of the biofilter is more sensitive to Henry＇s constant, the specific surface area of the filter bed and the thickness of water layer, while the filter bed pressure drop is more sensitive to biomass yield coefficient and original void fraction. The calculated toluene removal efficiency and bed pressure drop satisfactorily fit the experimental data under varied inlet toluene loadings, which indicates the model in this study can be used to predict VOCs removal and bed pressure drop simultaneously. Based on the model, the effect of mass-transfer parameters on VOCs removal and the stable-run time of a biofilter are analyzed. The results demonstrate that the model can function as a good tool to evaluate the effect of biomass accumulation and optimize the design and operation of biofilters.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFA1500500 and 2016YFA0200600)National Natural Science Foundation of China(Grant No.21790352)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB36000000)the Anhui Initiative in Quantum Information Technologies(Grant No.AHY090000)support from the China National Postdoctoral Program for Innovative Talents(No.BX2021282).
文摘The interaction between a probing tip and an adsorbed molecule can significantly impact the molecular chemical structure and even induce its motion on the surface.In this study,the tip-induced bond weakening,tilting,and hopping processes of a single molecule were investigated by sub-nanometre resolved tip-enhanced Raman spectroscopy(TERS).We used single carbon monoxide(CO)molecules adsorbed on the Cu(100)surface as a model system for the investigation.The vibrational frequency of the C−O stretching mode is always redshifted as the tip approaches,revealing the weakening of the C−O bond owing to tip−molecule interactions.Further analyses of both the vibrational Stark effect and TERS imaging patterns suggest a delicate tilting phenomenon of the adsorbed CO molecule on Cu(100),which eventually leads to lateral hopping of the molecule.While a tilting orientation is found toward the hollow site along the[110]direction of the Cu(100)surface,the hopping event is more likely to proceed via the bridge site to the nearest Cu neighbour along the[100]or[010]direction.Our results provide deep insights into the microscopic mechanisms of tip−molecule interactions and tip-induced molecular motions on surfaces at the single-bond level.
基金Supported by National Key Technology R&D Program Project in the 12~(th) Five-Year Plan:The 3~(rd) Hunan Special Project of Grain Bumper Science and Technology "The Integration and Demonstration of High-yield,Water-saving and Fertilizer-saving Techniques in the South Rice Area of Middle Reaches of Yangtze"(2013BAD07B11)Agro-scientific Research Programs in Public Interest "Study on the Change of Soil Fertility and Fertility Techniques in the Major Grain Producing Areas and the Demonstration"(201203030)International Cooperation Project"Study on the Efficient Nutrient Management Technology of Modern Double Cropping Rice in Hunan Province"(IPNI Hunan-18)~~
文摘In order to study the effects of controlled release nitrogen fertilizer （CRNF） application on rapeseed, a simulated experiment was carried out with 3 types of paddy soils in Dongting Lake area for 4 consecutive years of applying CRNF under double rice cropping system after planting rapeseed crop in the fallow season. The effects of CRNF application on rapeseed yield, agronomic characters and soil fertility were studied in this paper. The results showed that CRNF application improved the growth of rapeseed plant and increased rapeseed yield of CRNF treatments in the purple calcareous clayed paddy soil （PCS） and alluvial loamy paddy soil （ALS） which respectively increased by 12.2% and 9.8% compared with applying urea, re- spectively. The rapeseed yield in 70% CRNF treatment obviously decreased com- pared with urea treatment. The contents of available N and organic carbon in soil increased by 25.0% and 3.2% in CRNF treatment in the ALS after rapeseed crop, respectively; and available N increased by 13.5% in the PCS. Both rapeseed yield and soil fertility in CRNF treatment and 70% CRNF treatment were lower than those in CK treatment in the reddish yellow clayed paddy soil （RYS）. The results al- so indicated that the functions of CRNF application on rapeseed yield increase and soil nitrogen fertility improvement were very obvious in the PCS and ALS.
基金Supported by Key Project of Shandong Meteorological Bureau in 2015(2015sdqxz02)Project of Liaocheng Meteorological Bureau in 2015(2015lcqx11)~~
文摘Based on conventional observation data, NCEP reanalysis data, wind profiler radar, Doppler radar, and satellite cloud image data, two times of severe convection weather in the west of Shandong Province during June 13-14 in 2016 were analyzed. The results are shown as follows： firstly, the convection on the night of June 13 was stronger than that on the afternoon of June 14. The two times of severe convection weather generated under the circulation background of upper cold vortex. There was northwest air current at high altitudes and warm wet advection at low altitudes. Severe convection weather was triggered by low-level shear lines and surface convergence lines on June 13 and by weak cold air at 700 hPa on June 14 respectively. Secondly, there was certain water vapor transport and convergence before the occurrence of severe convection, and it was warm and wet at low altitudes but dry and cold at high altitudes; there was convergence at low altitudes and divergence at middle and high altitudes. 0 ℃ layer was at about 4 000 m, and-20 ℃ layer was at about 7 000 m. Thirdly, radar echo intensity was larger than 45 dBZ when severe convection happened, and it reached above 60 dBZ at an elevation of 1.5°, while middle strong echo zone overhung weak echo zone at low altitudes. Vertically integrated liquid（VIL） was up to 20 kg/m^2, and mesocyclone generated in strong echo zone; there was bow echo on the night of June 13, and VIL was higher than that on June 14. In wind profiler data, strong vertical wind shear and fluctuation of wind direction had denotative meaning to the occurrence of severe convection weather. Fourthly, hail, gale and other severe convection weather happened in front of long and narrow cold cloud zone and convective cloud clusters as well as in southwestern TBB gradient zone.
