Fine and hyperfine structures observed in the perturbation facilitated optical-optical double resonance ( PFOODR) excitation spectra of the K-2 2(3)Sigma(+)(g) state are analyzed within a model of the isolated multiplet using the case b(beta S) basis. It is concluded that Fermi contact and spin-spin interactions play the leading role. The values of the interaction constants are derived from their fitting to the experimental data. (C) 2010 Elsevier B. V. All rights reserved.