This stretching causes the light from these distant objects to be shifted into redder parts of the spectrum, meaning that observations in the near - to - mid infrared are necessary to capture the light from these galaxies. (sciencedaily.com)
The water splitting process only uses the higher energy photons leaving the infra red part of the spectrum untouched. (evworld.com)
With light, wavelength equates to energy and color; less energetic light trends toward the redder part of the spectrum than shorter - wavelength, bluer light. (discovermagazine.com)