Electronic structure of the bcc transition metals: Thermoreflectance studies of bulk V, Nb, Ta, andαTaHx

Thermoreflectance studies of bulk samples of V, Nb, Ta, and $\alpha$-phase $\mathrm{Ta}{\mathrm{H}}_x$ are reported and the results interpreted in terms of recent band calculations. The first interband transition is identified as a transition involving the $\Sigma$ band at $E_F$. An $M_3$ critical-point transition is attributed to states at $N$. Significant changes induced by interstitial hydrogen in solid solution $\alpha -\mathrm{Ta}{\mathrm{H}}_x$ are observed and interpreted as due to hybridization and lowering of the $N_1$ eigenenergy.