Processes involved between colliding droplets were investigated using simultaneous analysis of spectra and images of Raman-scattered light emitted by irradiation with a pulsed laser. This enabled spatially and temporally resolved Raman spectra of the colliding droplets to be obtained. Colliding droplets of ethanol and water produce a characteristic protrusion from the contact point to the antipode of the water droplet in the course of interaction. From its Raman spectrum, the protrusion is seen to be composed of water. This result supports our surface-tension release model previously proposed to describe the mechanism of protrusion formation because the protrusion is the result of positive interference of a capillary wave propagating over the surface of the water droplet in this model.