75As, 113,115In, and 123Sb NMR Studies of Indirect Nuclear Spin–Spin Coupling in InX (X=As, Sb)

Abstract

Indirect nuclear spin–spin coupling in InX (X=As, Sb) semiconductors has been investigated by magic-angle spinning (MAS) NMR for 75As, 113,115In and 123Sb spins. The coupling constants, J, of the isotropic indirect interaction for neighboring 113,115In–X (X=75As, 123Sb) spins were obtained as 478±10 and 730±40 Hz, respectively, from triple-resonance NMR experiments employing cross polarization from rare 113In to X and 115In decoupling during acquisition. The J values above and those for the 113,115In–121Sb spins were also estimated by a second moment analysis for the MAS NMR spectra of 75As, 113,115In and 123Sb spins, but the moment analysis provided values that deviated from the correct ones by a factor of up to 1.7. The reduced indirect coupling constant K was calculated from the above J values for InX (X=As, Sb) and the previously obtained value of J=224±5 Hz for InP [T. Iijima et al.: J. Phys. Soc. Jpn. 73 (2004) 1045]. The increase in K with decreasing band gap energy of the semiconductors of InX (X=P, As, Sb) was explained by considering that indirect coupling is dominated by the second-order perturbation energy of the nuclear–electron interaction with occupied and unoccupied states being in the valence and conduction bands, respectively.