title: Aspect-ratio- and size-dependent emergence of the surface-plasmon resonance in gold nanorods--an ab initio TDDFT study.
abstract: It is known that the surface-plasmon resonance (SPR) in small spherical Au nanoparticles of about 2 nm is strongly damped. We demonstrate that small Au nanorods with a high aspect ratio develop a strong longitudinal SPR, with intensity comparable to that in Ag rods, as soon as the resonance energy drops below the onset of the interband transitions due to the geometry. We present ab initio calculations of time-dependent density-functional theory of rods with lengths of up to 7 nm. By changing the length and width, not only the energy but also the character of the resonance in Au rods can be tuned. Moreover, the aspect ratio alone is not sufficient to predict the character of the spectrum; the absolute size matters.
authors.affiliation: Department of Physics & Astronomy, The University of Texas at San Antonio, One UTSA circle, 78249-0697 San Antonio, TX, USA. Xochitl.LopezLozano@utsa.edu.
authors.forename: Xóchitl
authors.initials: X
authors.lastname: López-Lozano
authors.forename: Hector
authors.initials: H
authors.lastname: Barron
authors.forename: Christine
authors.initials: C
authors.lastname: Mottet
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Weissker