Hydrogenated amorphous carbons, an important component of the interstellar carbonaceous
dust, possess infrared spectral signatures (at 3.4, 6.9 and 7.3 μm) that
are ubiquitous in the diffuse interstellar medium of galaxies, but not observed in dense
clouds. To better understand the role played by cosmic rays in the disappearance of these
absorption bands, irradiation experiments of hydrocarbon dust analogues have been
performed with different swift ions. The results obtained through the in situ
infrared monitoring of the samples during the irradiations allow to infer the
dehydrogenation effect of the cosmic ray distribution on the interstellar hydrogenated
amorphous carbons. The importance of this interstellar dust destruction by cosmic rays is
discussed in comparison to other energetic processes in different interstellar
environments.