Two kinds of forest-like and desert-like patterns are formed by thermal evaporation of 4-dicyanovinyl-N, Ndimethylamino-1-naphthalene (DDAN) onto SiO2 substrates. Based on thermal kinetics of the molecules on the su...Two kinds of forest-like and desert-like patterns are formed by thermal evaporation of 4-dicyanovinyl-N, Ndimethylamino-1-naphthalene (DDAN) onto SiO2 substrates. Based on thermal kinetics of the molecules on the substrate the transformation between the forest and desert patterns is due to two factors. The first one is the diffusion length, which is related to the deposition rate, the diffusion potential energy barrier and the substrate temperature. The second one is the strong interaction between the two polarity chemical groups of the molecules, which is beneficial to the formation of branches. Totally different patterns are also found on mica substrates, and are attributed to the anisotropic diffusion and the stronger interaction between DDAN molecules and the mica surface.展开更多
There are two basic kinds of photoemissive materials for the laser pulse detection.One is the photoemissive thin films containing alkali elements,such as Ag-O-Cs,Cs<sub>3</sub>Sb,[Cs]Na<sub>2</sub...There are two basic kinds of photoemissive materials for the laser pulse detection.One is the photoemissive thin films containing alkali elements,such as Ag-O-Cs,Cs<sub>3</sub>Sb,[Cs]Na<sub>2</sub>KSb.F.Gex et al.proposed that the Ag-O-Cs photocathode was the onlyphotoemissive material for detecting laser pulse with the duration≤10 ps and wavelength1.06μm.Another is pure metallic thin films,such as Au,Ag and Cu.The sensitivity ofphotocathodes containing alkali elements is higher than that of others,but this kind ofthin film cannot work at temperature higher than 150℃,nor can it be exposed to theatmosphere for the exposure will make it worthless.This causes the trouble for use。展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 90406022. the Hi-Tech Research and Development Programme of China under Grant No 2004AA302G11, and the National Basic Research Programme of China under Grant No 2006CB921305.
文摘Two kinds of forest-like and desert-like patterns are formed by thermal evaporation of 4-dicyanovinyl-N, Ndimethylamino-1-naphthalene (DDAN) onto SiO2 substrates. Based on thermal kinetics of the molecules on the substrate the transformation between the forest and desert patterns is due to two factors. The first one is the diffusion length, which is related to the deposition rate, the diffusion potential energy barrier and the substrate temperature. The second one is the strong interaction between the two polarity chemical groups of the molecules, which is beneficial to the formation of branches. Totally different patterns are also found on mica substrates, and are attributed to the anisotropic diffusion and the stronger interaction between DDAN molecules and the mica surface.
文摘There are two basic kinds of photoemissive materials for the laser pulse detection.One is the photoemissive thin films containing alkali elements,such as Ag-O-Cs,Cs<sub>3</sub>Sb,[Cs]Na<sub>2</sub>KSb.F.Gex et al.proposed that the Ag-O-Cs photocathode was the onlyphotoemissive material for detecting laser pulse with the duration≤10 ps and wavelength1.06μm.Another is pure metallic thin films,such as Au,Ag and Cu.The sensitivity ofphotocathodes containing alkali elements is higher than that of others,but this kind ofthin film cannot work at temperature higher than 150℃,nor can it be exposed to theatmosphere for the exposure will make it worthless.This causes the trouble for use。