High-Frequency ESR Measurements of S = 1/2 1-D Heisenberg Antiferromagnetic Zig-Zag Chain (VO)(SO4)(2,2-bpy)

High-frequency electron spin resonance (ESR) measurements of S = 1/2 one-dimensional Heisenberg antiferromagnetic zig-zag chain substance (VO)(SO4)(2,2-bpy) were performed in the temperature region from 1.8 to 265 K. ESR measurements at 265 K show typical powder pattern spectra of the V4+ ion and g || = 1.925 ± 0.001 and g ⊥ = 1.976 ± 0.001 were obtained. Although the magnetic susceptibility shows a maximum at 3.1 K suggesting the existence of a short-range order, no g-shift and line width broadening were observed down to 1.8 K. We suggest that these temperature-independent features of ESR can be attributed to the result of frustration in (VO)(SO4)(2,2-bpy).