The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 ...The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.展开更多
F-B co-doped TiO_(2)nanosheets with exposed anatase(001)facets were synthesized via a one-pot solvothermal method,and their photocatalytic hydrogen evolution performance was investigated.Characterization results confi...F-B co-doped TiO_(2)nanosheets with exposed anatase(001)facets were synthesized via a one-pot solvothermal method,and their photocatalytic hydrogen evolution performance was investigated.Characterization results confirm that this method effectively promotes the growth of the highly active anatase(001)facets and enhances visible and infrared light absorption while inducing oxygen vacancies.Under optimal conditions,the hydrogen evolution reaches 20.57μmol after 10 h of ultraviolet-visible(UV-Vis)light irradiation,exceeding the commercial TiO_(2)nanoparticles Degussa P25 by more than 10 times.These findings highlight the potential of F-B co-doped TiO_(2)nanosheets for efficient photocatalysis.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61405002,91336103,10934010,61535001 and 61078026
文摘The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.
基金National Natural Science Foundation of China(No.81861138040)。
文摘F-B co-doped TiO_(2)nanosheets with exposed anatase(001)facets were synthesized via a one-pot solvothermal method,and their photocatalytic hydrogen evolution performance was investigated.Characterization results confirm that this method effectively promotes the growth of the highly active anatase(001)facets and enhances visible and infrared light absorption while inducing oxygen vacancies.Under optimal conditions,the hydrogen evolution reaches 20.57μmol after 10 h of ultraviolet-visible(UV-Vis)light irradiation,exceeding the commercial TiO_(2)nanoparticles Degussa P25 by more than 10 times.These findings highlight the potential of F-B co-doped TiO_(2)nanosheets for efficient photocatalysis.
