  Black phosphorus has emerged as the next member in the graphene inspired
two-dimensional materials family. Its electronic and magnetic properties are
studied herein using electron and nuclear magnetic resonance techniques (ESR
and NMR) and microwave conductivity measurement. The latter is a unique
technique to study conductivity on air sensitive samples. The ESR study
indicates the absence of free charge carriers and no sign of paramagnetic
defects are found. $^{31}$P NMR shows the presence of a characteristic Pake
doublet structure due to the interaction between $I = 1/2$ nuclei. Microwave
conductivity shows, in accordance with the ESR results, that black phosphorus
behaves as a semiconductor and we identify extrinsic and intrinsic charge
carrier contributions to the conductivity and extracted the sizes of the gaps.
ESR measurement also yields that bP might find applications as a microwave
absorbent.
