1210.4274 (D. Ishikawa et al.)

X-ray Raman Scattering of Water Near the Critical Point: Comparison of
an Isotherm and Isochore    [PDF]

D. Ishikawa, Y. Q. Cai, D. M. Shaw, J. S. Tse, N. Hiraoka, A. Q. R. Baron

X-ray Raman spectra of liquid, sub- and super- critical water at the oxygen K-edge were measured, at densities 1.02 - 0.16 gcm^-3. Measurements were made along both an isotherm and an isochore passing near the critical point. As density is reduced there is a general tendency of the spectra to increasingly resemble that of the vapor phase, with, first, a well separated low-energy peak, and, eventually, at densities below the critical density, peaks appearing at higher energies corresponding to molecular transitions. The critical point itself is distinguished by a local maximum in the contrast between some of the spectroscopic features. The results are compared to computed X-ray absorption spectra of supercritical water.

View original: http://arxiv.org/abs/1210.4274