Distribution of the VIMOS sample in the infrared luminosity–redshift plane. The different colors represent the three stages of interactions: we show the “Class 0” single isolated objects in blue, the “Class 1” interacting galaxies in a pre-coalescence phase in green, and the “Class 2” objects representing single systems with evidence of having suffered a merger (post-coalescence phase) in red. The horizontal dashed line separates the LIRG and ULIRG domains.