RESUMO
A silicon substrate patterned by an oxide is immersed in an alcohol solution of low-doped 1-nm Si nanoparticles. Reverse biasing draws particles to the substrate, mostly along the conducting current paths. Scanning electron and fluorescence microscopy show a tree-like network on the substrate. Avoidance of closed loops and preference for an angle of branching of 90 degrees-120 degrees are observed. The building block of the tree network is not individual particles but spherical particle aggregates approximately 150 nm in diameter.
Assuntos
Cristalização/métodos , Eletroquímica/métodos , Campos Eletromagnéticos , Microscopia de Fluorescência/métodos , Silício/química , Coloides/química , Cristalografia/métodos , Fluorescência , Microscopia Eletrônica de Varredura , Conformação Molecular , Nanotecnologia/métodos , Tamanho da Partícula , Silício/isolamento & purificação , Propriedades de SuperfícieRESUMO
A three-photon process using radiation at 2430 and 3660 A and with a 1s-2s two-photon resonance is used to excite atomic hydrogen from the ground state to Rydberg states of high principal quantum number. Collision-induced ionization is used to monitor the excitation.
RESUMO
Hydrogen Rydberg states in a hydrogen plasma are optically excited from the plasma-excited n = 2 state. Photoionization and optogalvanic ionization, which is due to electron-impact ionization and other collisional processes, are used to monitor the Rydberg states. This process may be used to study collisional ionization of the Rydberg states.
