We present results from magnetic-resonance measurements for 75–350 GHz in ${\alpha }^{\prime }-{\mathrm{NaV}}_2{\mathrm{O}}_5.$ The temperature dependence of the integrated intensity indicates that we observe transitions in the excited state. A quantitative description gives resonances in the triplet state at high-symmetry points of the excitation spectrum of this spin-Peierls compound. This energy has the same temperature dependence as the spin-Peierls gap. Similarities and differences with another inorganic compound ${\mathrm{CuGeO}}_3$ are discussed.

• Received 17 July 1997

DOI:https://doi.org/10.1103/PhysRevB.57.2687