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Optical properties of large molecules and clusters in the frenkel exciton picture
Author(s) -
Avery John,
Hvidt Søren
Publication year - 1986
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560290322
Subject(s) - exciton , circular dichroism , dipole , molecular physics , optical rotatory dispersion , chemistry , inverse , molecule , absorption (acoustics) , matrix (chemical analysis) , linear dichroism , physics , atomic physics , condensed matter physics , quantum mechanics , crystallography , optics , geometry , mathematics , chromatography
Frenkel exciton theory is reviewed. This theory yields general formulas relating the absorption and circular dichroism spectra of large molecules or clusters to the optical properties of their subunits. It is shown that for weakly interacting systems, the circular dichroism associated with a band of exciton states is proportional to tr( FH ), where F is an “optical matrix” constructed from the positions and transition dipole moments of the subunits, and H is an interaction‐energy matrix. It is shown that if a system expnds isotropically, then tr( FH ) falls off as the inverse square of the linear dimensions. This result is compared with experimental measurements of the low‐temperature optical rotatory dispersion of proteins as a function of temperature. The optical properties of helical polymers are also discussed as a function of their geometrical parameters.