Resonance enhancement of x rays in layered materials: Application to surface enrichment in polymer blends

Abstract

Resonance enhancement of x rays of both odd and even orders has been observed in a thin polymer blend film of polystyrene (PS) and polybromostyrene $({\mathrm{PBr}}_{x}\mathrm{S})$ spin cast on a smooth Au layer on a silicon substrate. The x-ray intensity enhancement has been measured by detecting fluorescence from the Br atoms in the ${\mathrm{PBr}}_{x}\mathrm{S}$ component of the compatible polymer blend. Analysis of the Br K\ensuremath{\alpha} fluorescence has yielded the ${\mathrm{PBr}}_{x}\mathrm{S}$ distribution in the polymer blend layer in agreement with a PS surface enrichment model. PS is largely enriched at the free surface of the polymer layer and partially enriched at the underlying interface.