OPTICAL AND ACOUSTIC PLASMONS IN CYLINDRICAL QUANTUM-WELL WIRES

We study theoretically the collective electronic excitations of quasi- one-dimensional cylindrical quantum-well wires, the intrasubband and i ntersubband plasmons in the random-phase approximation. Using a two-su bband model we calculate the dispersion curves for the case that two s ubbands are occupied. We study the influence of the image forces on th e intrasubband and intersubband plasmons in detail. These modes are sp lit in two branches. The intrasubband plasmon branches can be classifi ed in an optical and an acoustic branch which are influenced quite dif ferently by the image forces. The intersubband plasmon branches behave like acoustic plasmons.