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Coherent acoustic and optical phonon oscillations in Bi nanowire samples were studied with a femtosecond pump-probe technique. Laser pulses of 50 fs excited simultaneously acoustic oscillations at a frequency of about 9.5 GHz and optical phonons in the terahertz range. The transmission signal of nanowires on a glass substrate and the signal of light scattered from freestanding nanowires were measured. The acoustic velocity in nanowires was found to be close to that of bulk polycrystalline material. The changes in the optical phonon frequency at different laser fluences were simulated taking into account excitation inhomogeneity, lattice anharmonicity, diffusion, and recombination of the carriers and gave good agreement with experimental results. [ABSTRACT FROM AUTHOR]

Abstract: Single-crystal Bi nanowires with a rhombohedral lattice structure of bulk Bi were electrochemically deposited into the pores of anodic aluminum oxide membranes. We report measurements of the longitudinal and the transverse magnetoresistance on single Bi nanowires of nominal diameters 100 and 20nm. [Copyright &y& Elsevier]

Abstract: Bi nanowires were electrochemically deposited into porous polycarbonate membranes of thickness 6μm and nominal pore diameter 80nm. They have the rhombohedral lattice structure of bulk Bi at ambient pressure. Resistance measurements on single Bi nanowires show evidence for superconductivity below 0.64K. [Copyright &y& Elsevier]