We study the plasma excitations of an array of two-dimensional electron-gas layers arranged in a Fibonacci sequence. The plasmon spectrum is analyzed by a transfer-matrix method. It is shown that the spectrum is always "critical," i.e., it corresponds to neither extended nor localized plasmon states. This property is reflected in the calculated Raman intensities.

• Received 14 March 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.380