A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central fre...A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.展开更多
Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Se...Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Setaria italica have been chosen as suitable monocotyledonous models for plants possessing the C4 pathway of photosynthesis including sorghum,maize,sugarcane,switchgrass and Miscanthus×giganteus.Accurate partial least squares regression（PLSR）models to predict S.italica stem composition have been generated,based upon Fourier transform mid-infrared（FTIR）spectra and calibrated with wet chemistry determinations of ground S.italica stem material measured using a modified version of the US National Renewable Energy Laboratory（NREL）acid hydrolysis protocol.The models facilitated a high-throughput screening analysis for glucan,xylan,Klason lignin and acid soluble lignin（ASL）in a collection of 183 natural S.italica variants and clustered them into classes,some possessing unique chemotypes.The predictive models provide a highly efficient screening tool for large scale breeding programs aimed at identifying lines or mutants possessing unique cell wall chemotypes.Genes encoding key catalytic enzymes of the lignin biosynthesis pathway exhibit a high level of conservation with matching expression profiles,measured by RT-q PCR,among accessions of S.italica,which closely mirror profiles observed in the different developmental regions of an elongating internode of S.viridis by RNASeq.展开更多
Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitr...Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitrogen content in petroleum and its products. The calibration models of nitrogen content in crude oils have been established by partial least squares (PLS) method. The results predicted by this method were very close to those determined by standard methods. Compared with standard methods, this method is provided with advantages such as high-speed, simplicity and good-repeat- ability without any needs for pretreatment.展开更多
Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We deve...Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We develop a truly noninvasive,glucose-monitoring technique using midinfrared spectroscopy that does not require blood collection for calibration by applying domain adaptation(DA)using deep neural networks to train a model that associates blood glucose concentration with mid-infrared spectral data without requiring a training dataset labeled with invasive blood sample measurements.For realizing DA,the distribution of unlabeled spectral data for calibration is considered through adversarial update during training networks for regression to blood glucose concentration.This calibration improved the correlation coeffcient between the true blood glucose concentrations and predicted blood glucose concentrations from 0.38 to 0.47.The result indicates that this calibration technique improves prediction accuracy for mid-infrared glucose measurements without any invasively acquired data.展开更多
Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This st...Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.展开更多
This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,t...This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,this paper draws a conclusion that IR has several advantages,including rapid analysis,excellent repeatability and low analysis cost.展开更多
To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the M...To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the MIR range of 3 200-700 cm-1 and NIR range of 9 000-4 000 cm-1.The spectral features in the two regions were analyzed.The MIR spectra of milk were characteristic due to the MIR inherent molecular specificity,whereas the NIR spectra were relatively characterless due to the NIR low selectivity.Partial least squares(PLS)regression models for fat and protein were developed by using both MIR and NIR spectra.MIR data with no pretreatment gave better results than NIR data.The square correlation coefficient(R2)and the root mean square error of prediction(RMSEP)were 0.98 and 0.10 g/dL for fat and 0.97 and 0.11 g/dL for protein.With NIR techniques,satisfactory results were not obtained with raw data.However,NIR data after pretreatment gave similarly good results to the ones using MIR method.This paper indicates that either of the MIR and NIR spectral methods is reliable for the determination of the fat and protein contents.展开更多
In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution witho...In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution without two-beam interference(TBI).Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth.Consequently,during reconstruction,high lateral and axial resolutions are obtained.Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications.In this study,a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated.A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept.We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging,fluorescence microscopy,mid-infrared fingerprinting,astronomical imaging,and fast object recognition applications.展开更多
Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser w...Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules.By applying this feature to the medical fields,less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers.A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation(DFG)between a Nd:YAG and a tunable Cr:forsterite lasers.The MIR-DFG laser was tunable in a wavelength range of 5.5–10μm and generated laser pulses with energy of up to 1.4mJ,a pulse width of 5 ns,and a pulse repetition rate of 10 Hz.Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75μm,which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions.We have developed a non-destructive diagnostic probe with an attenuated total reflection(ATR)prism and two hollow optical fibers.An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser,and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.展开更多
Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spect...Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser;lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.展开更多
The mid-infrared optical frequency comb is a powerful tool for gas sensing.In this study,we demonstrate a simple midinfrared dual-comb spectrometer covering 3±4μm in Li Nb O_(3)waveguides.Based on a low-power fi...The mid-infrared optical frequency comb is a powerful tool for gas sensing.In this study,we demonstrate a simple midinfrared dual-comb spectrometer covering 3±4μm in Li Nb O_(3)waveguides.Based on a low-power fiber laser system,the mid-infrared comb is achieved via intra-pulse difference frequency generation in the Li Nb O_(3)waveguide.We construct pre-chirp management before supercontinuum generation to control spatiotemporal alignment for pump and signal pulses.The supercontinuum is directly coupled into a chirped periodically poled Li Nb O_(3)waveguide for the 3±4μm idler generation.A mid-infrared dual-comb spectrometer based on this approach provides a 100 MHz resolution over25 THz coverage.To evaluate the applicability for spectroscopy,we measure the methane spectrum using the dualcomb spectrometer.The measured results are consistent with the HITRAN database,in which the root mean square of the residual is 3.2%.This proposed method is expected to develop integrated and robust mid-infrared dual-comb spectrometers on chip for sensing.展开更多
We report the development of a static magnetic eld Faraday rotation spectrometer for NO detection.A 5.33μm continuous-wave quantum cascade laser was used as the probing laser.Line absorption at 1875.81 cm^−1(2Π3=2Q(...We report the development of a static magnetic eld Faraday rotation spectrometer for NO detection.A 5.33μm continuous-wave quantum cascade laser was used as the probing laser.Line absorption at 1875.81 cm^−1(2Π3=2Q(3/2),v=1←0)was chosen for the detection.By using a Chernin type multipass cell,a detection precision of 1.15 ppbv(1σ,1s)was achieved with an absorption pathlength of 108 m.This value was reduced to 0.43 ppbv by increasing the data-acquisition time to 15 s.展开更多
Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated ele...Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated electrons in Ga_(2)O_(3) loaded with Cr_(2)O_(3)-Rh cocatalysts was studied using time-resolved mid-infrared spectroscopy.The structure of these Cr_(2)O_(3)-Rh cocatalysts was identified with high-resolution transmission electron microscopy and CO adsorption Fourier-transform infrared spectroscopy,as Rh particles partly covered with Cr_(2)O_(3).The decay dynamics of photogenerated electrons reveals that only the electrons trapped by the Rh particles efficiently participate in the H2 evolution reaction.The loaded Cr_(2)O_(3) promotes electron transfer from Ga_(2)O_(3) to Rh,which accelerates the electron-consuming reaction for H2 evolution.Based on these observations,a photocatalytic water-splitting mechanism for Cr_(2)O_(3)-Rh/Ga_(2)O_(3) photocatalysts has been proposed.The elucidation of the roles of the Cr_(2)O_(3)-Rh cocatalysts aids in further understanding the reaction mechanisms of photocatalytic water splitting and guiding the development of improved photocatalysts.展开更多
The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yie...The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.展开更多
基金Project supported by the National Key Scientific Instrument and Equipment Development,China(Grant No.2014YQ060537)the National Key Research and Development Program,China(Grant No.2016YFC0201103)
文摘A compact prototype based on mid-infrared wavelength modulation spectroscopy（WMS）is developed for the simul-taneous monitoring of NO,NO2,and NH3 in the urban area.Three quantum cascade lasers（QCLs）with central frequencies around 1900.0 cm^-1,1600.0 cm^-1,and 1103.4 cm^-1are used for NO,NO2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.
文摘Cell wall composition in monocotyledonous grasses has been identified as a key area of research for developing better feedstocks for forage and biofuel production.Setaria viridis and its close domesticated relative Setaria italica have been chosen as suitable monocotyledonous models for plants possessing the C4 pathway of photosynthesis including sorghum,maize,sugarcane,switchgrass and Miscanthus×giganteus.Accurate partial least squares regression（PLSR）models to predict S.italica stem composition have been generated,based upon Fourier transform mid-infrared（FTIR）spectra and calibrated with wet chemistry determinations of ground S.italica stem material measured using a modified version of the US National Renewable Energy Laboratory（NREL）acid hydrolysis protocol.The models facilitated a high-throughput screening analysis for glucan,xylan,Klason lignin and acid soluble lignin（ASL）in a collection of 183 natural S.italica variants and clustered them into classes,some possessing unique chemotypes.The predictive models provide a highly efficient screening tool for large scale breeding programs aimed at identifying lines or mutants possessing unique cell wall chemotypes.Genes encoding key catalytic enzymes of the lignin biosynthesis pathway exhibit a high level of conservation with matching expression profiles,measured by RT-q PCR,among accessions of S.italica,which closely mirror profiles observed in the different developmental regions of an elongating internode of S.viridis by RNASeq.
文摘Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitrogen content in petroleum and its products. The calibration models of nitrogen content in crude oils have been established by partial least squares (PLS) method. The results predicted by this method were very close to those determined by standard methods. Compared with standard methods, this method is provided with advantages such as high-speed, simplicity and good-repeat- ability without any needs for pretreatment.
文摘Noninvasive,glucose-monitoring technologies using infrared spectroscopy that have been studied typically require a calibration process that involves blood collection,which renders the methods somewhat invasive.We develop a truly noninvasive,glucose-monitoring technique using midinfrared spectroscopy that does not require blood collection for calibration by applying domain adaptation(DA)using deep neural networks to train a model that associates blood glucose concentration with mid-infrared spectral data without requiring a training dataset labeled with invasive blood sample measurements.For realizing DA,the distribution of unlabeled spectral data for calibration is considered through adversarial update during training networks for regression to blood glucose concentration.This calibration improved the correlation coeffcient between the true blood glucose concentrations and predicted blood glucose concentrations from 0.38 to 0.47.The result indicates that this calibration technique improves prediction accuracy for mid-infrared glucose measurements without any invasively acquired data.
文摘Arson presents a challenging crime scene for fire investigators worldwide. Key to the investigation of suspected arson cases is the analysis of fire debris for the presence of accelerants or ignitable liquids. This study has investigated the application and method development of vapor phase mid-Infrared (mid-IR) spectroscopy using a field portable quantum cascade laser (QCL) based system for the detection and identification of accelerant residues such as gasoline, diesel, and ethanol in fire debris. A searchable spectral library of various ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification of accelerants present in samples using software developed in-house. Measurement of vapors collected from paper material that had been doused with an accelerant followed by controlled burning and then extinguished with water showed that positive identification could be achieved for gasoline, diesel, and ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the sensitivity and discrimination capability that make it well suited for non-destructive crime scene sample analysis. Sampling and measurement can be performed in minutes with this 7.5 kg instrument. This vibrational spectroscopic method required no time-consuming sample pretreatment or complicated solvent extraction procedure. The results of this initial feasibility study demonstrate that this portable fire debris analyzer would greatly benefit arson investigators performing analysis on-site.
文摘This paper aims at testing oxygen and benzene contents in gasoline by mid-infrared spectroscopy.The experimental results prove that infrared spectroscopy(IR)is reliable.Compared with gas chromatography(GC)technology,this paper draws a conclusion that IR has several advantages,including rapid analysis,excellent repeatability and low analysis cost.
基金Supported by National Natural Science Foundation of China(No.30170261)the 10th Five-Year Plan of China(No.2004BA706B12).
文摘To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the MIR range of 3 200-700 cm-1 and NIR range of 9 000-4 000 cm-1.The spectral features in the two regions were analyzed.The MIR spectra of milk were characteristic due to the MIR inherent molecular specificity,whereas the NIR spectra were relatively characterless due to the NIR low selectivity.Partial least squares(PLS)regression models for fat and protein were developed by using both MIR and NIR spectra.MIR data with no pretreatment gave better results than NIR data.The square correlation coefficient(R2)and the root mean square error of prediction(RMSEP)were 0.98 and 0.10 g/dL for fat and 0.97 and 0.11 g/dL for protein.With NIR techniques,satisfactory results were not obtained with raw data.However,NIR data after pretreatment gave similarly good results to the ones using MIR method.This paper indicates that either of the MIR and NIR spectral methods is reliable for the determination of the fat and protein contents.
基金European Union’s Horizon 2020 research and innovation programme under grant agreement No.857627(CIPHR).
文摘In recent years,there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional(3D)information into a two-dimensional intensity distribution without two-beam interference(TBI).Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth.Consequently,during reconstruction,high lateral and axial resolutions are obtained.Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications.In this study,a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated.A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept.We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging,fluorescence microscopy,mid-infrared fingerprinting,astronomical imaging,and fast object recognition applications.
基金supported by Takeda Science Foundation,Japanese Foundation for Research and Promotion of Endoscopy,and Grants-in-Aid for Scientific Research(KAKENHI).
文摘Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared(MIR)wavelength region,selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules.By applying this feature to the medical fields,less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers.A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation(DFG)between a Nd:YAG and a tunable Cr:forsterite lasers.The MIR-DFG laser was tunable in a wavelength range of 5.5–10μm and generated laser pulses with energy of up to 1.4mJ,a pulse width of 5 ns,and a pulse repetition rate of 10 Hz.Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75μm,which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions.We have developed a non-destructive diagnostic probe with an attenuated total reflection(ATR)prism and two hollow optical fibers.An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser,and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.
文摘Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser;lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.
基金supported in part by the National Natural Science Foundation of China(Nos.12204178,12104162,12134004 and 12274141)。
文摘The mid-infrared optical frequency comb is a powerful tool for gas sensing.In this study,we demonstrate a simple midinfrared dual-comb spectrometer covering 3±4μm in Li Nb O_(3)waveguides.Based on a low-power fiber laser system,the mid-infrared comb is achieved via intra-pulse difference frequency generation in the Li Nb O_(3)waveguide.We construct pre-chirp management before supercontinuum generation to control spatiotemporal alignment for pump and signal pulses.The supercontinuum is directly coupled into a chirped periodically poled Li Nb O_(3)waveguide for the 3±4μm idler generation.A mid-infrared dual-comb spectrometer based on this approach provides a 100 MHz resolution over25 THz coverage.To evaluate the applicability for spectroscopy,we measure the methane spectrum using the dualcomb spectrometer.The measured results are consistent with the HITRAN database,in which the root mean square of the residual is 3.2%.This proposed method is expected to develop integrated and robust mid-infrared dual-comb spectrometers on chip for sensing.
基金supported by the National Key Research and Development Program of China(No.2016YFC0202205)the National Natural Science Foundation of China(No.41805104,No.41875151,and No.41627810)+2 种基金the Natural Science Foundation of Anhui Province(No.1508085J03)the Youth Innovation Promotion Association CAS(No.2016383)the CASHIPS Director's Fund(YZJJ2018QN7,BJPY2019B02).
文摘We report the development of a static magnetic eld Faraday rotation spectrometer for NO detection.A 5.33μm continuous-wave quantum cascade laser was used as the probing laser.Line absorption at 1875.81 cm^−1(2Π3=2Q(3/2),v=1←0)was chosen for the detection.By using a Chernin type multipass cell,a detection precision of 1.15 ppbv(1σ,1s)was achieved with an absorption pathlength of 108 m.This value was reduced to 0.43 ppbv by increasing the data-acquisition time to 15 s.
文摘Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated electrons in Ga_(2)O_(3) loaded with Cr_(2)O_(3)-Rh cocatalysts was studied using time-resolved mid-infrared spectroscopy.The structure of these Cr_(2)O_(3)-Rh cocatalysts was identified with high-resolution transmission electron microscopy and CO adsorption Fourier-transform infrared spectroscopy,as Rh particles partly covered with Cr_(2)O_(3).The decay dynamics of photogenerated electrons reveals that only the electrons trapped by the Rh particles efficiently participate in the H2 evolution reaction.The loaded Cr_(2)O_(3) promotes electron transfer from Ga_(2)O_(3) to Rh,which accelerates the electron-consuming reaction for H2 evolution.Based on these observations,a photocatalytic water-splitting mechanism for Cr_(2)O_(3)-Rh/Ga_(2)O_(3) photocatalysts has been proposed.The elucidation of the roles of the Cr_(2)O_(3)-Rh cocatalysts aids in further understanding the reaction mechanisms of photocatalytic water splitting and guiding the development of improved photocatalysts.
文摘The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.
