Coherent hypersonic closed-pipe organ like modes in supported polymer films

Hypersonic wavepackets were injected into polymer films of various thicknesses on a crystalline substrate, and quantized vibrational modes were detected. The acoustic spectrum showed up to six localized modes with frequencies determined by the boundary conditions for acoustic modes similar to those obtained in closed organ pipes. The decay rate of the modes was found to increase linearly with frequency in the gigahertz range. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3605567]