原子论的演变及启示

简要地分析了古代原子论提出的背景,阐述了古代原子论的诞生及其内容,介绍了近代科学原子论和现代物理原子结构理论,并阐释了几点有益的启示.     

Exciton States and Linear Optical Spectra of Semiconducting Carbon Nanotubes under Uniaxial Strain

Considering the exciton effect, the linear optical spectra of semiconducting single-walled carbon nanotubes （SWNTs） under uniaxial strain are theoretically studied by using the standard formulae of Orr and Ward [Mol. Phys. 20（1971）513]. It is found that due to the wrapping effect existing in the semiconducting zigzag tubes, the excitation energies of the linear optical spectra show two different kinds of variations with increasing uniaxial strain, among which one decreases such as tube （11,0）, and the other increases firstly and then decreases such as tube （10,0）. These variations of the linear optical spectra are consistent with the changes of the exciton binding energies or the （quasi）continuum edge of these SWNTs calculated in our previous work, which can be used as a supplemented tool to detect the deformation degree of an SWNT under uniaxial strain.     

Infrared Absorption Spectra of Undoped and Doped Few-Layer Graphenes

The infrared absorption spectra of undoped few-layer graphenes with the layer number of N = 1-6, the hole- and electron-doped few-layer graphenes with the layer number of N =1-4 have been studied based upon the tight-binding model. It is found that in contrast with the featureless optical spectrum of the undoped monolayer graphene, the undoped AB-stacking bi-, tri-, tetra- and more-layer graphene exhibit characteristic jumps in their infrared absorption （IR） spectra, which are caused by coupling between different layers. It is also found that the clear peaks exist in the IR spectra of the hole or electron-doped hi-, tri- and tetra-layer graphenes, which are induced by the strong IR transitions between their parallel valence or conduction bands. Based upon their different IR spectra, a powerful experimental tool has been proposed to identify accurately the layer number and doping type for the few-layer graphenes.