An ultra-narrow spectroscopy of clock transition with high signal-to-noise ratio is crucial for a high-performance atomic optical clock. We present a detailed study about how to obtain a Hertz-level clock transition s...An ultra-narrow spectroscopy of clock transition with high signal-to-noise ratio is crucial for a high-performance atomic optical clock. We present a detailed study about how to obtain a Hertz-level clock transition spectrum of 171 Yb atoms. About 4 × 10^4 atoms are loaded into a one-dimensional optical lattice with a magic wavelength of 759 nm, and a long lifetime of 3 s is realized with the lattice power of I W. Through normalized shelving detection and spin polarization, 171 Yb clock spectroscopy with a fourier-limited linewidth of 5.9 Hz is obtained. Our work represents a key step toward an ytterbium optical clock with high frequency stability.展开更多
The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yie...The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61227805,91536104 and 11574352
文摘An ultra-narrow spectroscopy of clock transition with high signal-to-noise ratio is crucial for a high-performance atomic optical clock. We present a detailed study about how to obtain a Hertz-level clock transition spectrum of 171 Yb atoms. About 4 × 10^4 atoms are loaded into a one-dimensional optical lattice with a magic wavelength of 759 nm, and a long lifetime of 3 s is realized with the lattice power of I W. Through normalized shelving detection and spin polarization, 171 Yb clock spectroscopy with a fourier-limited linewidth of 5.9 Hz is obtained. Our work represents a key step toward an ytterbium optical clock with high frequency stability.
文摘The catalytic pyrolysis of lignites is a technical process whose development is complex and time-consuming with the goal to maximize the yield of the desired low-volatile hydrocarbons of choice and to minimize the yield of solid residual products. Not every type of lignite is suitable for this process due to its particular chemical composition. In order to be able to predict which lignite specimen will be an especially promising raw material for the pyrolytic liberation of target products, the chemical classification by IR spectroscopic methods was investigated. MIR spectroscopy has been demonstrated to be a valuable tool to characterize the the molecular composition of lignites and to determine the concentrations of aliphatic and aromatic functional groups in lignite as well as alcoholic OH and other forms of bound oxygen. These data provide a comprehensive chemical characterization of the material and help to predict the composition of the chemical components liberated by catalytic decomposition. With a complementary NIR spectroscopic approach, a chemometric method has been developed with which the elemental com-position of the lignites can be determined in a fast and pragmatic way leading to a prediction of the product range of a theoretical pyrolytic product range. Thus, this spectroscopic investigation is a toolbox that can answer the question if the commercial exploitation of catalytic pyrolysis of a lignite sample in question will make sense without preliminary conduction of long and time-consuming testing.
基金National Natural Science Foundation of China(30772727)National Technology Support Project(2006BAI09B01)national S&T special projects(2009ZX09308-002)
