Absorption spectra of jet-cooled PH2 radicals were recorded in the wavelength range of 465- 555 nm using cavity ringdown spectroscopy. The PH2 radicals were produced in a supersonic jet by pulsed direct current discha...Absorption spectra of jet-cooled PH2 radicals were recorded in the wavelength range of 465- 555 nm using cavity ringdown spectroscopy. The PH2 radicals were produced in a supersonic jet by pulsed direct current discharge of a mixture of PHa and SF6 in argon. Seven vibronic bands with fine rotational structures have been observed and assigned as 0 0^, 2 0^n, and 2 1^n （n=1- 3） bands of the A^2A1- X~ 2B1 electronic transition. Rotational assignments and rotational term values for each band were re-identified, and the molecular parameters including rotational constants, centrifugal distortion constants, and spin-rotation interaction constants were also improved with reasonably high precision. In addition, large perturbations observed in each quantum number of total angular momentum of the a axis level of the excited vibronic states were briefly discussed.展开更多
Background:Lung cancer is one of the most common malignant tumors worldwide.Currently,effective screening methods for early lung cancer are still scarce.Breath analysis provides a promising method for the pre-screenin...Background:Lung cancer is one of the most common malignant tumors worldwide.Currently,effective screening methods for early lung cancer are still scarce.Breath analysis provides a promising method for the pre-screening or early screening of lung cancer.Isoprene is a potential and important breath biomarker of lung cancer.Material and Methods:To investigate the clinical value of isoprene for diagnosing lung cancer patients,a cavity ringdown spectroscopy(CRDS)based near-real time,sensitive analysis method of breath isoprene is developed in our lab.In this paper,92 breath samples from lung cancer patients,17 breath samples from patients with benign lesions,and 107 breath samples from healthy people were collected.Results:Research indicates that breath isoprene concentration is significantly higher in healthy individuals(221:3±122:2 ppbv)than in patients with lung cancer(112:0±36:6 ppbv)and benign lung lesions(127:9±41:2 ppbv).The result of Receiver Operating Characteristic(ROC)curve suggests that the concentration of isoprene is meaningful for the diagnosis of lung cancer(AUC=0:822,sensitivity=63:6%,specificity=90:2%,P<0:01).Conclusion:This study demonstrates that the CRDS breath isoprene analysis system can effectively analyze a large sample of human breath isoprene,and preliminarily confirms the use of breath isoprene as a biomarker for lung diseases.展开更多
The absolute number density of nitrogen dioxide（NO2） seeded in argon is measured with cavity-enhanced laserinduced fluorescence（CELIF） through using a pulsed laser beam for the first time. The cavity ring down（CR...The absolute number density of nitrogen dioxide（NO2） seeded in argon is measured with cavity-enhanced laserinduced fluorescence（CELIF） through using a pulsed laser beam for the first time. The cavity ring down（CRD） signal is acquired simultaneously and used for normalizing the LIF signal and determining the relationship between the measured CELIF signal and the NO2 number density. The minimum detectable NO2 density down to（3.6±0.1）10^8 cm^-3 is measured in 60 s of acquisition time by the CELIF method. The minimum absorption coefficient is measured to be（2.0±0.1）10^-9 cm^-1, corresponding to a noise equivalent absorption sensitivity of（2.2±0.1）10^9 cm.^-1Hz^-1/2. The experimental system demonstrated here can be further improved in its sensitivity and used for environmental monitoring of outdoor NO2 pollution.展开更多
H_(2)S is one of the most important characteristic decomposition components of SF_(6)insulated gas,and the detection of trace H_(2)S is significant for early fault diagnosis of gas insulated electrical equipment.A 157...H_(2)S is one of the most important characteristic decomposition components of SF_(6)insulated gas,and the detection of trace H_(2)S is significant for early fault diagnosis of gas insulated electrical equipment.A 1578 nm wavelength distributed feedback diode laser(DFB-DL)based cavity ring-down spectroscopy(CRDS)experimental platform is developed to monitor the concentrations of H_(2)S in SF_(6)and SF_(6)/N_(2)mixture carrier gas.The detection sensitivity is higher than 1×10^(-6).The absorption cross section parameterσis vital for calculating the concentration.With repeated experiments using standard gas samples,parameterσof H_(2)S in pure SF_(6)and SF_(6)/N_(2)mixture carrier with different mixing ratios is calibrated.Compared with the simulatedσvalues,the influence of carrier gas on the broadening of spectral profile is discussed.The variation of absorption cross sectionσwith different carrier gas mixing ratios is studied as well,so that the calculation of the concentration in the carrier gas of any mixing ratio is possible.Thus,the application of CRDS in trace component detection of gas insulated electrical equipment is promising.展开更多
Cavity ringdown spectroscopy(CRDS),relying on measuring the decay time of photons inside a high-finesse optical cavity,offers an important analytical tool for chemistry,physics,environmental science,and biology.Throug...Cavity ringdown spectroscopy(CRDS),relying on measuring the decay time of photons inside a high-finesse optical cavity,offers an important analytical tool for chemistry,physics,environmental science,and biology.Through the reflection of a slight amount of phase-coherent light back to the laser source,the resonant optical feedback approach effectively couples the laser beam into the optical cavity and achieves a high signal-to-noise ratio.However,the need for active phaselocking mechanisms complicates the spectroscopic system,limiting its primarily laboratory-based use.Here,we report how passive optical feedback can be implemented in a quantum cascade laser(QCL) based CRDS system to address this issue.Without using any phase-locking loops,we reflect a moderate amount of light(–18.2 dB) to a continuous-wave QCL simply using a fixed flat mirror,narrowing the QCL linewidth from 1.2 MHz to 170 kHz and significantly increasing the laser-cavity coupling efficiency.To validate the method's feasibility and effectiveness,we measured the absorption line(P(18e),2207.62 cm^(−1)) of N_(2)O in a Fabry–Perot cavity with a high finesse of ~52000 and an inter-mirror distance of 33 cm.This agile approach paves the way for revolutionizing existing analytical tools by offering compact and high-fidelity mid-infrared CRDS systems.展开更多
腔衰荡光谱技术(Cavity Ring Down Spectroscopy,CRDS)具有高精度和高灵敏度,是一种常应用于微量气体浓度检测的方法,而采用这项技术的关键就是衰荡时间的准确获取。本文为此设计一种基于LabVIEW的腔衰荡信号在线处理系统,实现对衰荡信...腔衰荡光谱技术(Cavity Ring Down Spectroscopy,CRDS)具有高精度和高灵敏度,是一种常应用于微量气体浓度检测的方法,而采用这项技术的关键就是衰荡时间的准确获取。本文为此设计一种基于LabVIEW的腔衰荡信号在线处理系统,实现对衰荡信号的实时采集、平均、拟合、显示和保存。采用外部调制二极管激光器和高反腔搭建CRDS装置,获取实际的衰荡信号,用该系统处理测得的衰荡信号与其他软件的处理结果对比。实验表明,所编写的在线腔衰荡信号处理系统,可实现对衰荡时间的准确获取。展开更多
基金This work was supported by the National Natural Science Foundation of China （No.20673107）, the National Key Basic Research Special Foundation of China （No.2007CB815203）, and the Chinese Academy of Sciences （No.KJCX2-SW-H08）.
文摘Absorption spectra of jet-cooled PH2 radicals were recorded in the wavelength range of 465- 555 nm using cavity ringdown spectroscopy. The PH2 radicals were produced in a supersonic jet by pulsed direct current discharge of a mixture of PHa and SF6 in argon. Seven vibronic bands with fine rotational structures have been observed and assigned as 0 0^, 2 0^n, and 2 1^n （n=1- 3） bands of the A^2A1- X~ 2B1 electronic transition. Rotational assignments and rotational term values for each band were re-identified, and the molecular parameters including rotational constants, centrifugal distortion constants, and spin-rotation interaction constants were also improved with reasonably high precision. In addition, large perturbations observed in each quantum number of total angular momentum of the a axis level of the excited vibronic states were briefly discussed.
基金support provided by The Chinese Academy of Medical Sciences Initiative for Innovative Medicine(2018-I2M-AI-012).
文摘Background:Lung cancer is one of the most common malignant tumors worldwide.Currently,effective screening methods for early lung cancer are still scarce.Breath analysis provides a promising method for the pre-screening or early screening of lung cancer.Isoprene is a potential and important breath biomarker of lung cancer.Material and Methods:To investigate the clinical value of isoprene for diagnosing lung cancer patients,a cavity ringdown spectroscopy(CRDS)based near-real time,sensitive analysis method of breath isoprene is developed in our lab.In this paper,92 breath samples from lung cancer patients,17 breath samples from patients with benign lesions,and 107 breath samples from healthy people were collected.Results:Research indicates that breath isoprene concentration is significantly higher in healthy individuals(221:3±122:2 ppbv)than in patients with lung cancer(112:0±36:6 ppbv)and benign lung lesions(127:9±41:2 ppbv).The result of Receiver Operating Characteristic(ROC)curve suggests that the concentration of isoprene is meaningful for the diagnosis of lung cancer(AUC=0:822,sensitivity=63:6%,specificity=90:2%,P<0:01).Conclusion:This study demonstrates that the CRDS breath isoprene analysis system can effectively analyze a large sample of human breath isoprene,and preliminarily confirms the use of breath isoprene as a biomarker for lung diseases.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504112,91536218,and 11604100)
文摘The absolute number density of nitrogen dioxide（NO2） seeded in argon is measured with cavity-enhanced laserinduced fluorescence（CELIF） through using a pulsed laser beam for the first time. The cavity ring down（CRD） signal is acquired simultaneously and used for normalizing the LIF signal and determining the relationship between the measured CELIF signal and the NO2 number density. The minimum detectable NO2 density down to（3.6±0.1）10^8 cm^-3 is measured in 60 s of acquisition time by the CELIF method. The minimum absorption coefficient is measured to be（2.0±0.1）10^-9 cm^-1, corresponding to a noise equivalent absorption sensitivity of（2.2±0.1）10^9 cm.^-1Hz^-1/2. The experimental system demonstrated here can be further improved in its sensitivity and used for environmental monitoring of outdoor NO2 pollution.
基金supported in part by the National Key R&D Program of China(No.2021YFF0603100)in part by the Leading Innovation and Entrepreneurship Team in Zhejiang Province(No.2019R01014)
文摘H_(2)S is one of the most important characteristic decomposition components of SF_(6)insulated gas,and the detection of trace H_(2)S is significant for early fault diagnosis of gas insulated electrical equipment.A 1578 nm wavelength distributed feedback diode laser(DFB-DL)based cavity ring-down spectroscopy(CRDS)experimental platform is developed to monitor the concentrations of H_(2)S in SF_(6)and SF_(6)/N_(2)mixture carrier gas.The detection sensitivity is higher than 1×10^(-6).The absorption cross section parameterσis vital for calculating the concentration.With repeated experiments using standard gas samples,parameterσof H_(2)S in pure SF_(6)and SF_(6)/N_(2)mixture carrier with different mixing ratios is calibrated.Compared with the simulatedσvalues,the influence of carrier gas on the broadening of spectral profile is discussed.The variation of absorption cross sectionσwith different carrier gas mixing ratios is studied as well,so that the calculation of the concentration in the carrier gas of any mixing ratio is possible.Thus,the application of CRDS in trace component detection of gas insulated electrical equipment is promising.
基金National Natural Science Foundation of China(NSFC)(52122003,62305279),ChinaInnovation and Technology Fund(GHP/129/20SZ)from the Innovation and Technology Commission,Hong Kong SAR,China+1 种基金Collaborative Research Fund(C4002-22Y)General Research Fund(14208221)from the University Grants Committee,Hong Kong SAR,China.
文摘Cavity ringdown spectroscopy(CRDS),relying on measuring the decay time of photons inside a high-finesse optical cavity,offers an important analytical tool for chemistry,physics,environmental science,and biology.Through the reflection of a slight amount of phase-coherent light back to the laser source,the resonant optical feedback approach effectively couples the laser beam into the optical cavity and achieves a high signal-to-noise ratio.However,the need for active phaselocking mechanisms complicates the spectroscopic system,limiting its primarily laboratory-based use.Here,we report how passive optical feedback can be implemented in a quantum cascade laser(QCL) based CRDS system to address this issue.Without using any phase-locking loops,we reflect a moderate amount of light(–18.2 dB) to a continuous-wave QCL simply using a fixed flat mirror,narrowing the QCL linewidth from 1.2 MHz to 170 kHz and significantly increasing the laser-cavity coupling efficiency.To validate the method's feasibility and effectiveness,we measured the absorption line(P(18e),2207.62 cm^(−1)) of N_(2)O in a Fabry–Perot cavity with a high finesse of ~52000 and an inter-mirror distance of 33 cm.This agile approach paves the way for revolutionizing existing analytical tools by offering compact and high-fidelity mid-infrared CRDS systems.
文摘腔衰荡光谱技术(Cavity Ring Down Spectroscopy,CRDS)具有高精度和高灵敏度,是一种常应用于微量气体浓度检测的方法,而采用这项技术的关键就是衰荡时间的准确获取。本文为此设计一种基于LabVIEW的腔衰荡信号在线处理系统,实现对衰荡信号的实时采集、平均、拟合、显示和保存。采用外部调制二极管激光器和高反腔搭建CRDS装置,获取实际的衰荡信号,用该系统处理测得的衰荡信号与其他软件的处理结果对比。实验表明,所编写的在线腔衰荡信号处理系统,可实现对衰荡时间的准确获取。
