Infrared absorption in bismuth nanowires resulting from quantum confinement

Results are reported for experimentally measured and theoretically predicted optical absorption in bismuth nanowires. Five absorption peaks are seen in the experimental spectral range. The energies of these five peaks agree well with the predicted values for intersubband transitions, thereby validating our model of quantum confinement in bismuth nanowires. We also compare the measured absorption in free-standing wires to the absorption of wires inside an alumina template obtained from an analysis of transmission and reflection measurements using a reverse effective-medium theory. Close agreement between the energies of the largest absorption peak is found by the two methods. The weaker absorption peaks were not observed in the spectrum of wires embedded in alumina.