Nanosecond time-resolved infrared spectra of photoexcited 9,9'-bianthryl (BA) and its deuterated derivative (BA-d(18)) were recorded in acetonitrile-d(3) and cyclohexane-d(12). The charge-transfer (CT) bands observed at the 1200-1400 cm(-1) region are contributed mostly by the intra- and inter-ring CC stretch vibrations. The intrinsic frequency of the inter-ring CC stretch falls within the 1200-1400 cm(-1) region, which is consistent more with a twisted structure than with a fully conjugated planar structure of the CT state.