Fig. 4.

Diffraction representing three phases. (Upper) Diffraction before (Left), during (Center), and after (Right) the transformation, taken from the same sample area of irradiation. Three prominent diffraction rings are indexed in the image. (Lower) Radially averaged diffraction profiles of respective images shown above. To fit a transient-frame diffraction profile (Center), the negative-time (Left) and asymptotic profile (Right) are combined in proportion of their contributions. For the quality of a fit, the difference between the transient-frame profile and the fitted one is also depicted. The high signal-to-noise proved essential for the accuracy reported here.