EXPERIMENTAL-DESIGN IN GLOBAL COMPARTMENTAL ANALYSIS OF REVERSIBLE INTRAMOLECULAR 2-STATE EXCITED-STATE PROCESSES WITH ADDED QUENCHER

Although reversible intramolecular two-state excited-state processes w ithout a priori information are unidentifiable, bounds on the excited- state rate constants k(ij) can be specified when a quencher is used [V an Dommelen et al. J. Phys. Chem. 1993, 97, 11738]. These limits can b e obtained by a scanning procedure consisting of a series of global co mpartmental analyses of a fluorescence decay surface in which one of t he rate constants k(ij) is held fixed at different preset values. The theory requires that the rate constants of quenching (k(Q1), k(Q2)) fo r the two excited species have different values. In the present paper, computer-generated fluorescence decay surfaces are used to investigat e the criteria under which reliable estimates of the bounds on the rat e constants k(ij) can be obtained. If the values of k(Q1) and k(Q2) ar e substantially different, reliable estimates are obtained. If k(Q1) a nd k(Q2) are nearly equal in value, the quality of the estimates of th e bounds depends on the combinations of the values of the rate constan ts k(ij). It may happen that no reliable Limits for the rate constants can be obtained so that another quencher is required. A test procedur e based on a limited number of decay traces is described which allows one to assess the appropriateness of the quencher for the given excite d-state process.