Nonlinear optical properties of one-dimensional organic molecular aggregates in nanometer films

R. V. MarkovCorresponding Author Contact Information, E-mail The Corresponding Author, a, A. I. Plekhanova, V. V. Shelkovnikovb and J. Knoesterc

a Institute of Automation and Electrometry, Novosibirsk, Russia
b Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia
c Institute for Theoretical Physics and Materials Science Center, University of Groningen, Groningen, The Netherlands

Available online 20 June 2003.


Nanometer films of molecular J-aggregates of pseudoisocyanine (PIC) with various degrees of both static and dynamic disorder were prepared. The amount of static disorder was varied by modifying the local environment of the J-aggregates in the films, while the dynamic disorder was varied by changing the film temperature. Through these variations, the delocalization length Ndel of the excitons was controlled, as could be monitored from the width of the exciton absorption line. This has allowed us to establish the scaling of the nonlinear optical susceptibility per aggregate molecule, small chi, Greek(3)/N, with the delocalization length as small chi, Greek(3)/N ~ Ndelsmall gamma, Greek, with small gamma, Greek=2.3±0.2. This behavior turned out to be independent of the detailed nature of disorder, and agrees very well with the theoretically predicted size-enhancement of the cubic susceptibility in J-aggregates.

Author Keywords: Cubic susceptibility; J-aggregates; Exciton delocalization length

PACS classification codes: 42.65.An; 42.70.Jk; 71.35.Cc; 73.20.Mf

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