Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted c...Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted coastal regions and industrialized areas. We report the development of a Xe arc lamp based near-ultraviolet （335-375 nm） incoherent broad- band cavity enhanced absorption spectroscopy （IBBCEAS） spectrometer for quantitative assessment of OC10 in an atmospheric simulation chamber. The important intermediate compound CH20, and other key atmospheric trace species （NO2） were also simultaneously measured. The instrumental performance shows a strong potential of this kind of IBBCEAS instrument for field and laboratory studies of atmospheric halogen chemistry.展开更多
Direct-comb spectroscopy techniques uses optical frequency combs(OFCs)as spectroscopic light source.They deliver high sensitivity,high frequency resolution and precision in a broad spectral range.Due to these features...Direct-comb spectroscopy techniques uses optical frequency combs(OFCs)as spectroscopic light source.They deliver high sensitivity,high frequency resolution and precision in a broad spectral range.Due to these features,the field has burgeoned in recent years.In this work we constructed an OFC-based cavity-enhanced Fourier-transform spectrometer in the nearinfrared region and used it for a line-shape study of rovibrational transitions of CO perturbed by Ar.The highly sensitive measurements spanned the wavenumber range from 6270 cm^-1 to 6410 cm^-1,which covered both P and R branch of the second overtone band of CO.The spectrometer delivers high-resolution surpassing the Fourier-transform resolution limit determined by interferogram length,successfully removing ringing and broadening effects caused by instrumental line shape function.The instrumental-line-shape-free method and high signal-to-noise ratio in the measurement allowed us to observe collisional effects beyond those described by the Voigt profile.We retrieved collisional line-shape parameters by fitting the speed-dependent Voigt profile and found good agreement with the values given by precise cavity ring-down spectroscopy measurements that used a continuous-wave laser referenced to a stabilized OFC.The results demonstrate that OFC-based cavity-enhanced Fouriertransform spectroscopy is a strong tool for accurate line-shape studies that will be crucial for future spectral databases.展开更多
Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman ef...Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman effect, the pressure shift and the power shift are taken into consideration. The magnitudes of those shifts caused by various effects are evaluated. In order to reproduce the stability of 5.7 × 10^-14 obtained by Edwards, all necessary conditions are given. The results show that when there is a larger external magnetic field, the Zeeman shift could not be neglected, so that the shield should be employed. And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect. The results also show that at least 4-2.5℃ temperature control for cavity can effectively prevent several effects and improve the frequency stability.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.41005017）, the Instrument Developing Project of the Chinese Academy of Sciences （No.YZ201121）, Jiangsu Provincial Natural Science Foundation of China （No.BK2011829）, and the Open Research Fund of Key Laboratory of Atmospheric Composition and Optical Radiation. The support of the Groupement de Recherche International SAMIA between CNRS （National Center for Scientific Research, France）, RFBR （Russian Foundation for Basic Research, Russia）, and CAS （Chinese Academy of Sciences, China） is acknowledged. We thank Dr. Albert A. Ruth at university college cork for the helpful discussion on the Xe lamp source based IBBCEAS.
文摘Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted coastal regions and industrialized areas. We report the development of a Xe arc lamp based near-ultraviolet （335-375 nm） incoherent broad- band cavity enhanced absorption spectroscopy （IBBCEAS） spectrometer for quantitative assessment of OC10 in an atmospheric simulation chamber. The important intermediate compound CH20, and other key atmospheric trace species （NO2） were also simultaneously measured. The instrumental performance shows a strong potential of this kind of IBBCEAS instrument for field and laboratory studies of atmospheric halogen chemistry.
文摘Direct-comb spectroscopy techniques uses optical frequency combs(OFCs)as spectroscopic light source.They deliver high sensitivity,high frequency resolution and precision in a broad spectral range.Due to these features,the field has burgeoned in recent years.In this work we constructed an OFC-based cavity-enhanced Fourier-transform spectrometer in the nearinfrared region and used it for a line-shape study of rovibrational transitions of CO perturbed by Ar.The highly sensitive measurements spanned the wavenumber range from 6270 cm^-1 to 6410 cm^-1,which covered both P and R branch of the second overtone band of CO.The spectrometer delivers high-resolution surpassing the Fourier-transform resolution limit determined by interferogram length,successfully removing ringing and broadening effects caused by instrumental line shape function.The instrumental-line-shape-free method and high signal-to-noise ratio in the measurement allowed us to observe collisional effects beyond those described by the Voigt profile.We retrieved collisional line-shape parameters by fitting the speed-dependent Voigt profile and found good agreement with the values given by precise cavity ring-down spectroscopy measurements that used a continuous-wave laser referenced to a stabilized OFC.The results demonstrate that OFC-based cavity-enhanced Fouriertransform spectroscopy is a strong tool for accurate line-shape studies that will be crucial for future spectral databases.
基金Project supported by the Provincial Natural Science Funds of Shanxi Province, China (Grant No 20041037)the Industrial R&D Programme of Shanxi Province, China (Grant No 2006031118-04)
文摘Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman effect, the pressure shift and the power shift are taken into consideration. The magnitudes of those shifts caused by various effects are evaluated. In order to reproduce the stability of 5.7 × 10^-14 obtained by Edwards, all necessary conditions are given. The results show that when there is a larger external magnetic field, the Zeeman shift could not be neglected, so that the shield should be employed. And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect. The results also show that at least 4-2.5℃ temperature control for cavity can effectively prevent several effects and improve the frequency stability.
