1.
Phys Rev Lett
; 97(14): 143903, 2006 Oct 06.
Article
in English
| MEDLINE
| ID: mdl-17155253
ABSTRACT
We demonstrate up-conversion of noncoherent sunlight realized by ultralow excitation intensity. The bimolecular up-conversion process in our systems relies on the presence of a metastable triplet excited state, and thus has dramatically different photophysical characteristics relative to the other known methods for photon up-conversion (two-photon absorption, parametric processes, second harmonic generation, sequential multiphoton absorption, etc.).