Formation, Evolution and Destruction of Possible DIB Carriers: Dirty Molecular Hydrogen Ice Clusters

We suggest that the diffuse interstellar bands (DIBs) are absorption lines arising from electronic transitions in molecular clusters primarily composed of a single molecule, atom, or ion (``seed''), embedded in a single-layer shell of H₂ molecules (Bernstein et al. 2013). We refer to these clusters as CHCs (Contaminated H₂ Clusters). CHCs arise from cm-sized, dirty H₂ ice balls, called CHIMPs (Contaminated H₂ Ice Macro-Particles), formed in cold, dense, Giant Molecular Clouds (GMCs), and later released into the interstellar medium (ISM) upon GMC disruption. Absorption by the CHIMP of a UV photon releases CHCs. CHCs produce DIBs when they absorb optical photons. When this occurs, the absorbed photon energy disrupts the CHC.