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Compartmental Modeling of the Fluorescence Anisotropy Decay of a Cylindrically Symmetric Brownian Rotor: Identifiability Analysis
Author(s) -
Boens Noël,
Novikov Eugene,
Ameloot Marcel
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600309
Subject(s) - rotational diffusion , anisotropy , excited state , brownian motion , physics , excitation , isotropy , identifiability , molecular physics , fluorescence anisotropy , chemistry , fluorescence , atomic physics , optics , quantum mechanics , mathematics , statistics
We present the results of the deterministic identifiability analysis based on similarity transformation for models of one‐state excited‐state events of cylindrically symmetric rotors in isotropic environments undergoing rotational diffusion described by Brownian reorientation. Such an analysis on error‐free time‐resolved fluorescence (anisotropy) data can reveal whether the parameters of the considered model can be determined. The fluorescence δ‐response functions I || ( t ) and I ⊥ ( t ), for fluorescence polarized respectively parallel and perpendicular to the electric vector of linearly polarized excitation, are used to construct, in convenient matrix form, expressions of the sum S ( t )= I || ( t )+2 I ⊥ ( t ), the difference D ( t )= I || ( t )− I ⊥ ( t ), and the time‐resolved fluorescence anisotropy r ( t )= D ( t )/ S ( t ). The identifiability analysis of r ( t ) demonstrates that the rotational diffusion coefficients D || and D ⊥ for rotation respectively about and perpendicular to the symmetry axis can be uniquely resolved. However, the polar and azimuthal angles defining the absorption and emission transition moments in the molecular reference frame are not individually identifiable. Nevertheless, the difference between the polar angles of these transition moments is uniquely determined.