Intersubband transitions in bismuth nanowires

Optical absorption associated with the one-dimensional joint density of states of an intersubband transition in bismuth nanowires is reported. The previously observed strong absorption in bismuth nanowires at ∼1000 cm−1 is here shown to depend on the wire diameter and on the polarization of the incident light. The absorption line shape, the decreasing frequency with increasing wire diameter, and the polarization dependence of the reflectivity, all indicate that this resonance is due to an intersubband absorption resulting from quantum-confinement effects.