Kohn's theorem [1] is no longer applicable to multi-component systems, which consist of more than two kinds of electrons with di erent cyclotron frequencies. In such systems, cyclotron resonance (CR) is generally modi ed by electron-electron interaction in its positions and lineshapes. In this paper, interaction e ects on two-component CR is studied in asymmetric double quantum well (QW) system...

We map the complete plasmonic spectrum of silver nanodisks by electron energy loss spectroscopy and show that the mode which couples strongest to the electron beam has radial symmetry with no net dipole moment. Therefore, this mode does not couple to light and has escaped from observation in optical experiments. This radial breathing mode has the character of an extended two-dimensional surface...

The program of measurements at SLAC on superconduct. I ;r. ing niobium cavities is described. Results for TE and TM mode X-band cavities are presented. An RF magnetic breskdown field of 960 gauss and Q values greater than 1011 were measured for an electron beam welded TEOII mode cavity at ‘I 10.5 GHz. The best result for a TM mode cavity was a Q of 1.4 x log and a breakdown field of 360 gauss, ...

The existence of multipole surface-plasmon modes at simple-metal surfaces is demonstrated both experimentally and theoretically. Inelastic reAection electron-scattering experiments on smooth films of K and Na show loss peaks originating from the ordinary surface plasmon as well as from a higher-energy multipole mode. Microscopic density-functional calculations of the electron-loss function repr...

Both depletion-mode and enhancement-mode two-dimensional electron gases (2DEGs) in isotopically enriched Si with extremely high mobility (522 000 cm/V s) are presented. The samples were grown by chemical vapor deposition using enriched silane. The fraction of the spin-carrying isotope Si was reduced to the level of 800 ppm by Si enrichment, with the electron spin dephasing time expected to be a...

A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG(10) and HG(01) modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a pl...