Abstract
The investigation of the temperature dependences of microwave surface impedance and complex conductivity of V3Si single crystals with different stoichiometry allowed to observe a number of peculiarities which are in remarkable contradiction with single-gap Bardeen-Cooper-Schrieffer theory. At the same time, they can be well described by the two-band model of superconductivity, thus strongly evidencing the existence of two distinct energy gaps with zero-temperature values Δ1 ≈ 1.8 Tc and Δ2 ≈ 0.95 Tc in V3Si.