Structural fluctuations in expanded fluid Se accompanying the semiconductor-metal transition

We carried out small angle X-ray scattering (SAXS) measurements for expanded fluid Se up to the semiconductor-metal (SC-M) transition region and found that there appears a broad peak in the SAXS profiles in the temperature range from 1273 K to 1873 K at 60 MPa in addition to the critical scattering with the Ornstein-Zernike behaviour. The spectra were fitted using a model function and two characteristic lengths, the domain size of the dense and rare regions, and the correlation length concerning with the damping behaviour, were obtained. The present results suggest peculiar density fluctuations accompanying the SC-M transition in fluid Se