| 1 | OPTICAL PROPERTIES OF GeO_2 AND Ge NANOCRYSTALS显示文摘he co m pound m aterial of n m size particles Ge O2 Si O2 w as synthesied through hydrolysis of Si( O C2 H4) and Ge Cl4 . A heat treatm ent w as carried out for the sa m ples at 100 ~1200 ℃in air . Its optical property w as deter mined by U V Vis spectur m . We have found that theabsorption edge of spectru m shifted progressively to longer w avelengths . The quantu m size ef fect of nanocrystals appears because crystals gro w and energy of optical band gap reduces d ueto the influence of te m perature . By the analysis of X ray diffraction w e have observed theprocess in w hich the structure of particles changed fro m disorder into order . | Y.H.Zhou 1) ,Y.Y.Feng 2) and H.Y.Lu 2) 1)Department of Physics Nanjing Normal University, Nanjing 210097,China 2)Physics and Ch寁O P T I C A L P R O P E R T I E S O F Ge O2 A N D Ge N A N O C R Y S T A L S Y. H. Zhou1) , Y. Y. Feng2) | 1999 | Acta Metallurgica Sinica(English Letters)1999，12，5： | 22 |
| 2 | Proton beams from intense laser-solid interaction:Effects of the target materials显示文摘We report systematic studies of laser-driven proton beams produced with micrometer-thick solid targets made of aluminum and plastic,respectively.Distinct effects of the target materials are found on the total charge,cutoff energy,and beam spot of protons in the experiments,and these are described well by two-dimensional particle-in-cell simulations incorporating intrinsic material properties.It is found that with a laser intensity of 8×10^(19) W/cm^(2),target normal sheath acceleration is the dominant mechanism for both types of target.For a plastic target,the higher charge and cutoff energy of the protons are due to the greater energy coupling efficiencies from the intense laser beams,and the larger divergence angle of the protons is due to the deflection of hot electrons during transport in the targets.We also find that the energy loss of hot electrons in targets of different thickness has a significant effect on the proton cutoff energy.The consistent results obtained here further narrow the gap between simulations and experiments. | Y.X.Geng D.Wu W.Yu Z.M.Sheng S.Fritzsche Q.Liao M.J.Wu X.H.Xu D.Y.Li W.J.Ma H.Y.Lu Y.Y.Zhao X.T.He J.E.Chen C.Lin X.Q.Yan | 2020 | Matter and Radiation at Extremes2020，5，6： | 0 |
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