NIR confocal reflectance spectra around aqueous alteration bands (OH-stretching on top, H₂O-bending on bottom) for the non-irradiated Murchison pellet area (left), and the highest fluence of irradiation for argon (central) and helium (right) ions. For the stretching mode: the gray line indicates the 2.71 μm position on each plot, the dotted line indicates the band minimum shifting toward longer wavelength with increasing irradiation dose.