An ordered colloidal structure of SiO_(2) spheres of 0.33μm diameter has been formed in distilled water.It is a face-centered cubic structure with a lattice constant of 0.54μm and a volume fraction of 0.48,as determ...An ordered colloidal structure of SiO_(2) spheres of 0.33μm diameter has been formed in distilled water.It is a face-centered cubic structure with a lattice constant of 0.54μm and a volume fraction of 0.48,as determined by the Kossel rings analysis.The light transmission in the[111]direction exhibited a dip located at 11600cm^(-1).A plane wave expansion method is used to calculate the lowest gap at the L point.The gap center coincides quite well with the measured transmission dip.展开更多
The Trapping force on Rayleigh particles in an optical tweezers system with an oil immersion objective is calculated by an electromagnetic model.The results indicate that the stability of particles trapped will be aff...The Trapping force on Rayleigh particles in an optical tweezers system with an oil immersion objective is calculated by an electromagnetic model.The results indicate that the stability of particles trapped will be affected by spherical aberration,which is caused by refractive difference between objective oil and water solution,when the specimen manipulated is suspended in a water solution.The trapping force and depth of potential well will decrease and the minimum of laser power for ensuring the stability of particles trapped will increase with the enhancing trapping depth.展开更多
A procedure for fabricating novel TiO_(2) membrane materialwith sub-micrometre pores and large specific surface area from the template has been demonstrated. The morphology and structure of the membrane have been char...A procedure for fabricating novel TiO_(2) membrane materialwith sub-micrometre pores and large specific surface area from the template has been demonstrated. The morphology and structure of the membrane have been characterized by scanning electron microscopy. The results have indicated that the macroporous membraneconsists of uniform hollow spheres which are interconnected to each other by 'small windows'. Potential unique applications of this macroporous materialin the fields of catalysis, optics, sensors, etc, are suggested.展开更多
We have prepared a silica colloidal crystal with ethanol, which has a face-centered cubic structure and a corresponding photonic band gap located in the visible region, determined by Kossel ring analysis and the trans...We have prepared a silica colloidal crystal with ethanol, which has a face-centered cubic structure and a corresponding photonic band gap located in the visible region, determined by Kossel ring analysis and the transmission spectra. A special feature is an apparent variation of its lattice constant, as well as the gap frequency, with sample height. The Raman scattering induced by a picosecond laser at different heights of the colloidal crystal has been measured. It is found that the intensity of the Raman scattering is not related sensitively to the photonic gap, even though the Raman-Stokes wavelength is inside the gap.展开更多
A novel two-dimensional photonic crystal that possesses absolute photonic band gaps for both transverse-magnetic and transverse-electric polarized waves is proposed.Plane wave method is used for calculating their phot...A novel two-dimensional photonic crystal that possesses absolute photonic band gaps for both transverse-magnetic and transverse-electric polarized waves is proposed.Plane wave method is used for calculating their photonic band structures.Results show that,for this structure,two absolute photonic band gaps appear in dielectric cylinders periodically imbedded in an air background.展开更多
when 3s3p(1p)of Mg is resonantly excited by a dye laser,the bright and directional emission at 5184Åcan be observed.We have measured its intensity and temporal behavior in different Mg density.This emission is be...when 3s3p(1p)of Mg is resonantly excited by a dye laser,the bright and directional emission at 5184Åcan be observed.We have measured its intensity and temporal behavior in different Mg density.This emission is believed to be the superfluorescence,whose upper level is populated by inelastic collisions between excited Mg atoms.展开更多
The energy-pooling collision cross section for the transfer from 3s3p^(1)P to 3s4s^(3)S of Mg has been determined by measuring the relative intensity of the fluorescence at 5184Åand 2852Å.The average cross s...The energy-pooling collision cross section for the transfer from 3s3p^(1)P to 3s4s^(3)S of Mg has been determined by measuring the relative intensity of the fluorescence at 5184Åand 2852Å.The average cross section is(3.1±40%)×10^(-15)cm^(2).By considering the influence of radiation trapping and other uncertain effects,the absolute uncertainty of our measurement is within one order of magnitude.展开更多
We report the first detection of the effect of Na-Na spin exchange collisions on spin relaxation of optically pumped Na in Xe gas by studying the relaxation in the'dark"of the variable<SZ>in a mixture o...We report the first detection of the effect of Na-Na spin exchange collisions on spin relaxation of optically pumped Na in Xe gas by studying the relaxation in the'dark"of the variable<SZ>in a mixture of dense sodium vapor(number density[Na]~10^(13 )cm^(-3)),and buffer gas helium,xenon and nitrogen as a function of[Na]and xenon pressure.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.69477003。
文摘An ordered colloidal structure of SiO_(2) spheres of 0.33μm diameter has been formed in distilled water.It is a face-centered cubic structure with a lattice constant of 0.54μm and a volume fraction of 0.48,as determined by the Kossel rings analysis.The light transmission in the[111]direction exhibited a dip located at 11600cm^(-1).A plane wave expansion method is used to calculate the lowest gap at the L point.The gap center coincides quite well with the measured transmission dip.
基金Supported by the National Natural Science Foundation of China under Grant No.1989380.
文摘The Trapping force on Rayleigh particles in an optical tweezers system with an oil immersion objective is calculated by an electromagnetic model.The results indicate that the stability of particles trapped will be affected by spherical aberration,which is caused by refractive difference between objective oil and water solution,when the specimen manipulated is suspended in a water solution.The trapping force and depth of potential well will decrease and the minimum of laser power for ensuring the stability of particles trapped will increase with the enhancing trapping depth.
基金Supported by the National Natural Science Foundation of China.
文摘A procedure for fabricating novel TiO_(2) membrane materialwith sub-micrometre pores and large specific surface area from the template has been demonstrated. The morphology and structure of the membrane have been characterized by scanning electron microscopy. The results have indicated that the macroporous membraneconsists of uniform hollow spheres which are interconnected to each other by 'small windows'. Potential unique applications of this macroporous materialin the fields of catalysis, optics, sensors, etc, are suggested.
基金Supported by the National Natural Science Foundation of China under Grant No.19774073.
文摘We have prepared a silica colloidal crystal with ethanol, which has a face-centered cubic structure and a corresponding photonic band gap located in the visible region, determined by Kossel ring analysis and the transmission spectra. A special feature is an apparent variation of its lattice constant, as well as the gap frequency, with sample height. The Raman scattering induced by a picosecond laser at different heights of the colloidal crystal has been measured. It is found that the intensity of the Raman scattering is not related sensitively to the photonic gap, even though the Raman-Stokes wavelength is inside the gap.
基金Supported by the National Natural Science Foundation of China under Grant No.19574069.
文摘A novel two-dimensional photonic crystal that possesses absolute photonic band gaps for both transverse-magnetic and transverse-electric polarized waves is proposed.Plane wave method is used for calculating their photonic band structures.Results show that,for this structure,two absolute photonic band gaps appear in dielectric cylinders periodically imbedded in an air background.
文摘when 3s3p(1p)of Mg is resonantly excited by a dye laser,the bright and directional emission at 5184Åcan be observed.We have measured its intensity and temporal behavior in different Mg density.This emission is believed to be the superfluorescence,whose upper level is populated by inelastic collisions between excited Mg atoms.
文摘The energy-pooling collision cross section for the transfer from 3s3p^(1)P to 3s4s^(3)S of Mg has been determined by measuring the relative intensity of the fluorescence at 5184Åand 2852Å.The average cross section is(3.1±40%)×10^(-15)cm^(2).By considering the influence of radiation trapping and other uncertain effects,the absolute uncertainty of our measurement is within one order of magnitude.
文摘We report the first detection of the effect of Na-Na spin exchange collisions on spin relaxation of optically pumped Na in Xe gas by studying the relaxation in the'dark"of the variable<SZ>in a mixture of dense sodium vapor(number density[Na]~10^(13 )cm^(-3)),and buffer gas helium,xenon and nitrogen as a function of[Na]and xenon pressure.
