title: On the use of Purcell factors for plasmon antennas.
abstract: The Purcell factor is the standard figure of merit for spontaneous emission enhancement in microcavities and has also been proposed to describe emission enhancements for plasmonic resonances. A comparison of quality factor, mode volume, and Purcell factor for single and coupled plasmon spheres to exact calculations of emission rates shows that a Purcell factor derived from quality factor and mode volume does not describe emission changes due to plasmon antennas.
authors.affiliation: Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Sciencepark 104, NL-1098XG Amsterdam, The Netherlands. f.koenderink@amolf.nl
authors.forename: A F
authors.initials: AF
authors.lastname: Koenderink