2D material of graphene has inspired huge interest in fabricating of solid state gas sensors.In this work,epitaxial graphene,quasi-free-standing graphene,and CVD epitaxial graphene samples on SiC substrates are used t...2D material of graphene has inspired huge interest in fabricating of solid state gas sensors.In this work,epitaxial graphene,quasi-free-standing graphene,and CVD epitaxial graphene samples on SiC substrates are used to fabricate gas sensors.Defects are introduced into graphene using SF6 plasma treatment to improve the performance of the gas sensors.The epitaxial graphene shows high sensitivity to NO2 with response of 105.1%to 4 ppm NO2 and detection limit of 1 ppb.The higher sensitivity of epitaxial graphene compared to quasi-free-standing graphene,and CVD epitaxial graphene was found to be related to the different doping types of the samples.展开更多
Nitrogen-vacancy color centers can perform highly sensitive and spatially resolved quantum measurements of physical quantities such as magnetic field,temperature,and pressure.Meanwhile,sensing so many variables at the...Nitrogen-vacancy color centers can perform highly sensitive and spatially resolved quantum measurements of physical quantities such as magnetic field,temperature,and pressure.Meanwhile,sensing so many variables at the same time often introduces additional noise,causing a reduced accuracy.Here,a dual-microwave time-division multiplexing protocol is used in conjunction with a lock-in amplifier in order to decouple temperature from the magnetic field and vice versa.In this protocol,dual-frequency driving and frequency modulation are used to measure the magnetic and temperature field simultaneously in real time.The sensitivity of our system is about 3.4 nT=√Hz p and 1.3 mK=√Hz p,respectively.Our detection protocol not only enables multifunctional quantum sensing,but also extends more practical applications.展开更多
The Er/Ybco-doped Y2 WO6 phosphors were prepared via high temperature solid method for the first time. The structure was investigated with X-ray diffraction(XRD). The crystal morphology was observed through scanning e...The Er/Ybco-doped Y2 WO6 phosphors were prepared via high temperature solid method for the first time. The structure was investigated with X-ray diffraction(XRD). The crystal morphology was observed through scanning electron microscopy(SEM). Under the excitation of 980 nm diode laser,visible up-conversion(UC) emissions were observed in green and red regions. The luminescence study reveals strong ~4 Sto ~4 Itransition at 545 nm and strong ~4 Fto ~4 Itransition at 657 nm. The relative intensities ratios of red(510-580 nm) to green(640-690 nm) emissions(R) reduce when the samples co-doped with Ybions. The dependence of emission intensity on the pump power indicate that visible UC emissions are governed by two photons, meanwhile three photons process is also involved. For more details, the discussion is made in the energy level diagrams.展开更多
基金supported by the National Natural Science Foundation of China (61674131 and 61306006)
文摘2D material of graphene has inspired huge interest in fabricating of solid state gas sensors.In this work,epitaxial graphene,quasi-free-standing graphene,and CVD epitaxial graphene samples on SiC substrates are used to fabricate gas sensors.Defects are introduced into graphene using SF6 plasma treatment to improve the performance of the gas sensors.The epitaxial graphene shows high sensitivity to NO2 with response of 105.1%to 4 ppm NO2 and detection limit of 1 ppb.The higher sensitivity of epitaxial graphene compared to quasi-free-standing graphene,and CVD epitaxial graphene was found to be related to the different doping types of the samples.
基金supported by the National Natural Science Foundation of China(Nos.12005218 and 52130510).
文摘Nitrogen-vacancy color centers can perform highly sensitive and spatially resolved quantum measurements of physical quantities such as magnetic field,temperature,and pressure.Meanwhile,sensing so many variables at the same time often introduces additional noise,causing a reduced accuracy.Here,a dual-microwave time-division multiplexing protocol is used in conjunction with a lock-in amplifier in order to decouple temperature from the magnetic field and vice versa.In this protocol,dual-frequency driving and frequency modulation are used to measure the magnetic and temperature field simultaneously in real time.The sensitivity of our system is about 3.4 nT=√Hz p and 1.3 mK=√Hz p,respectively.Our detection protocol not only enables multifunctional quantum sensing,but also extends more practical applications.
基金Project supported by the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions(CIT&TCD201404030)Scientific Research Common Program of Beijing Municipal Commission of Education(SQKM201710011009)National Natural Science Foundation of China(21576002,61705003)
文摘The Er/Ybco-doped Y2 WO6 phosphors were prepared via high temperature solid method for the first time. The structure was investigated with X-ray diffraction(XRD). The crystal morphology was observed through scanning electron microscopy(SEM). Under the excitation of 980 nm diode laser,visible up-conversion(UC) emissions were observed in green and red regions. The luminescence study reveals strong ~4 Sto ~4 Itransition at 545 nm and strong ~4 Fto ~4 Itransition at 657 nm. The relative intensities ratios of red(510-580 nm) to green(640-690 nm) emissions(R) reduce when the samples co-doped with Ybions. The dependence of emission intensity on the pump power indicate that visible UC emissions are governed by two photons, meanwhile three photons process is also involved. For more details, the discussion is made in the energy level diagrams.
