A quantitative analysis of excitonic superhyperchromism in porphyrin J-/H-aggregates

Yildirim H., Iseri E., Gulen D.

CHEMICAL PHYSICS LETTERS, vol.391, pp.302-307, 2004 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 391
  • Publication Date: 2004
  • Doi Number: 10.1016/j.cplett.2004.05.009
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.302-307
  • Middle East Technical University Affiliated: No


We argue that the mixing between energetically well-separated bands should have a magnified importance in the aggregates exhibiting an excitonic structure with a collective superstate, for which the J-/H-aggregates of porphyrins represent excellent examples. We present a quantitative account of the excitonic intensity borrowing in such systems and reveal a remarkably simple explanation of its enhancement: superhyperchromism is manifested by the mediation of the interband (Q-B) coupling between the two superstates (in Q and B) of such aggregates. The significance of the superhyperchromism is conveyed through its effects on the absorption spectrum of a natural 'porphyrin J-aggregate' - the chlorosome. (C) 2004 Elsevier B.V. All rights reserved.