Brillouin scattering in salol: DeterminingTcof the mode coupling theory

Brillouin scattering spectra of the molecular glass former salol were combined with ultrasonic measurements to evaluate the nonergodicity parameter of mode coupling theory ${\mathit{f}}_0$(T). It was found to exhibit a weak cusp at a temperature ${\mathit{T}}_{\mathit{c}}^{\mathit{B}}$=275±10 K in reasonable agreement with the mode-coupling crossover temperature ${\mathit{T}}_{\mathit{c}}$=256±5 K found recently by other methods. This result is in marked contrast to the recent publication of Elmroth, Borjesson, and Torell [Phys. Rev. Lett. 68, 79 (1992)].