TY - JOUR

T1 - Identifiability analysis of models for reversible intermolecular two-state excited-state processes coupled with species-dependent rotational diffusion monitored by time-resolved fluorescence depolarization

AU - Szubiakowski, J P

AU - Dale, R E

AU - Boens, N

AU - Ameloot, M

PY - 2004/10/22

Y1 - 2004/10/22

N2 - A deterministic identifiability analysis of the kinetic model for a reversible intermolecular two-state excited-state process with species-dependent rotational diffusion described by Brownian reorientation is presented. The cases of both spherically and cylindrically symmetric rotors, with no change in the principal axes of rotation on interconversion in the latter case, are specifically considered. The identifiability analysis is carried out in terms of compartmental modeling based on the S(t)=I-parallel to(t)+2I(perpendicular to)(t) and D(t)=I-parallel to(t)-I-perpendicular to(t) functions, where I-parallel to(t) and I-perpendicular to(t) are the delta-response functions for fluorescence, polarized, respectively, parallel and perpendicular to the electric vector of linearly polarized excitation. It is shown that, from polarized time-resolved fluorescence data collected at two concentrations of coreactant and three appropriately chosen emission wavelengths, (a) a unique set of rate constants for the overall excited-state process is always obtained by making use of polarized measurements and (b) the rotational diffusion constants and geometrical factors associated with the different anisotropy decay components can be uniquely determined and assigned to each species. The geometrical factors are determined by the absorption and emission transitions in the two rotating species. For spherical rotors, these factors depend directly on the relative orientations of the transition moments, while for cylindrically symmetric rotors they depend on the orientations with respect to each other and to the symmetry axis. (C) 2004 American Institute of Physics.

AB - A deterministic identifiability analysis of the kinetic model for a reversible intermolecular two-state excited-state process with species-dependent rotational diffusion described by Brownian reorientation is presented. The cases of both spherically and cylindrically symmetric rotors, with no change in the principal axes of rotation on interconversion in the latter case, are specifically considered. The identifiability analysis is carried out in terms of compartmental modeling based on the S(t)=I-parallel to(t)+2I(perpendicular to)(t) and D(t)=I-parallel to(t)-I-perpendicular to(t) functions, where I-parallel to(t) and I-perpendicular to(t) are the delta-response functions for fluorescence, polarized, respectively, parallel and perpendicular to the electric vector of linearly polarized excitation. It is shown that, from polarized time-resolved fluorescence data collected at two concentrations of coreactant and three appropriately chosen emission wavelengths, (a) a unique set of rate constants for the overall excited-state process is always obtained by making use of polarized measurements and (b) the rotational diffusion constants and geometrical factors associated with the different anisotropy decay components can be uniquely determined and assigned to each species. The geometrical factors are determined by the absorption and emission transitions in the two rotating species. For spherical rotors, these factors depend directly on the relative orientations of the transition moments, while for cylindrically symmetric rotors they depend on the orientations with respect to each other and to the symmetry axis. (C) 2004 American Institute of Physics.

UR - http://www.scopus.com/inward/record.url?scp=8444252174&partnerID=8YFLogxK

U2 - 10.1063/1.1798972

DO - 10.1063/1.1798972

M3 - Article

SN - 1089-7690

VL - 121

SP - 7829

EP - 7839

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

IS - 16

ER -