Electron spin relaxation and frequency-dependent lineshape analysis of the 5′—ATP—Mn(II)—Trp system

A frequency-dependent lineshape analysis of the ESR spectra of ternary systems in solution has been carried out. The 5′-ATP—Mn(II)—Trp complex has been chosen as a model system. The analysis points out the presence of inverted spectra at both X- and Q-bands. The lineshape is described by a distribution of configurational sites, Y^l(ω) = Σ_kP_kY_k(H). The temperature dependence of the ESR linewidth has also been investigated and is discussed in terms of chemical equilibria and correlation times.