Temperature-induced momentum-dependent spectral weight transfer in Bi2Sr2CaCu2O8+delta     

Z Shen  PJ White  DL Feng  C Kim  GD Gu  H Ikeda  R Yoshizaki  N Koshizuka 《Science (New York, N.Y.)》1998,280(5361):259-262

Angle-resolved photoemission data from the cuprate superconductor Bi2Sr2CaCu2O8+delta above and below the superconducting transition temperature Tc reveal momentum-dependent changes that extend up to an energy of about 0.3 electron volt, or 40kTc (where k is the Boltzmann constant). The data suggest an anomalous transfer of spectral weight from one momentum to another, involving a sizable momentum transfer Q approximately (0.45pi, 0). The observed Q is intriguingly near the charge-order periodicity required if fluctuating charge stripes are present.  相似文献   

Mass-independent oxygen isotope fractionation in atmospheric CO as a result of the reaction CO + OH     

T Rockmann  CAM Brenninkmeijer  G Saueressig  P Bergamaschi  JN Crowley  H Fischer  PJ Crutzen 《Science (New York, N.Y.)》1998,281(5376):544-546

Atmospheric carbon monoxide (CO) exhibits mass-independent fractionation in the oxygen isotopes. An 17O excess up to 7.5 per mil was observed in summer at high northern latitudes. The major source of this puzzling fractionation in this important trace gas is its dominant atmospheric removal reaction, CO + OH --> CO2 + H, in which the surviving CO gains excess 17O. The occurrence of mass-independent fractionation in the reaction of CO with OH raises fundamental questions about kinetic processes. At the same time the effect is a useful marker for the degree to which CO in the atmosphere has been reacting with OH.  相似文献   

Fullerene pipes   总被引：10，自引：0，他引：10  

J Liu  AG Rinzler  H Dai  JH Hafner  RK Bradley  PJ Boul  A Lu  T Iverson  K Shelimov  CB Huffman  F Rodriguez-Macias  YS Shon  TR Lee  DT Colbert  RE Smalley 《Science (New York, N.Y.)》1998,280(5367):1253-1256

Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal suspension in water with the help of surfactants. These suspensions permit a variety of manipulations, such as sorting by length, derivatization, and tethering to gold surfaces.  相似文献