Radial band structure of electrons in liquid metals

The electronic band structure of a liquid metal was investigated by measuring precisely the evolution of angle-resolved photoelectron spectra during the melting of a Pb monolayer on a Si(111) surface. We found that the liquid monolayer exhibits a free-electron-like band and it undergoes a coherent radial scattering, imposed by the radial correlation of constituent atoms, to form a characteristic secondary hole band. These unique double-radial bands and their gradual evolution during melting can be quantitatively reproduced, including detailed spectral intensity profiles, with our radial scattering model based on a theoretical prediction of 1962. Our result establishes the radial band structure as a key concept for describing the nature of electrons in strongly disordered states of matter.     

Low-threshold supercontinuum generation in highly nonlinear chalcogenide nanowires

We demonstrate low-threshold supercontinuum generated in a highly nonlinear arsenic selenide chalcogenide nanowire with tailored dispersion. The tapered submicrometer chalcogenide fiber exhibits an ultrahigh nonlinearity, n(2) approximately 1.1x10(-17) m(2)/W and an effective mode area of 0.48 mum(2), yielding an effective nonlinearity of gamma approximately 93.4 W/m, which is over 80,000 times larger than standard silica single-mode fiber at a wavelength of approximately 1550 nm. This high nonlinearity, in conjunction with the engineered anomalous dispersion, enables low-threshold soliton fission leading to large spectral broadening at a dramatically reduced peak power of several watts, corresponding to picojoule energy.     

具有内生人口转变的Ramsey模型与仿真(Ⅰ)

本文将内生人口转变函数引入经典的Ramsey模型.通过解家庭效用最大化问题得到一个二维的动力系统,文中证明描述模型的动力系统至少存在一个非零平衡点并着重讨论非零平衡点惟一的情形.通过数值仿真得出在最优经济增长轨道上人口转变时期的人口变化对人均消费有本质的影响,而对人均资本影响不大.