Growth and optical absorption properties of silver nanorod arrays in porous anodic aluminum oxide templates

Silver nanorod arrays have been fabricated by alternating current (AC) and pulsed direct current (DC) electrodeposition in porous anodic aluminum oxide (AAO) templates with controlled pore diameters of 19, 38, and 65 nm, respectively. The variation of their optical absorption properties with the incident angle and the nanorods length (corresponding to the electrodeposition time) has been investigated. Optical absorption spectra show that the position of longitudinal surface plasmon resonance (LSPR) peak has a small blueshift with the increase of incident angle of the excitation light. While the aspect ratio of the nanorods increases, the position of LSPR peak first redshifts and then blueshifts to a certain wavelength. Furthermore, the position of LSPR peak can be tuned, ranging from 550 nm to 900 nm, which makes it possible to couple various wavelength of excitation source to assist radiative energy transfer to the acceptor.