Single-pulse imaging of transient changes of the NW and the calculated temperatures. (Upper) Single-pulse imaging of the NW length reduction due to eutectic-related reactions. The NW shrank along its axial direction, while its lateral width had no obvious change. Approximately 70% length reduction of the NW (without the top bead) was observed after a total of 46 laser shots. The rulers (white lines) indicate the NW length. The electric field polarization of the laser pulse was parallel to the long axis of the NW. (Lower Left) Volume change of the NW. The volume of GaAs NW reduces, while that of top bead increases. The total volume slightly decreases. (Lower Right) Calculated temperatures at different laser fluences. The temperature of Au or GaAs bead was estimated by assuming 100% of the component, while the effective temperature of the bead was calculated by considering the Au:GaAs ratio in the bead. The dotted line represents the lowest temperature to trigger the reaction. Because of the large latent heat of GaAs, the GaAs NW has not melted, although the temperatures (without taking account of the latent heat) are higher than its melting point (dashed line) at high fluences. The solid red line indicates the actual temperature of the GaAs NW when its latent heat is considered.