Infrared-active vibron bands associated with substitutional impurities in solid parahydrogen

We present a model for the line shapes of infrared-active Q(1)(0) vibron bands observed in solid parahydrogen doped with low concentrations of spherical substitutional impurities. The line shapes are highly sensitive to the H-2 vibrational dependence of the dopant-H-2 interaction. When this vibrational dependence is strong, the dopant can trap the infrared-active vibron in its first solvation shell; in this case, the trapped vibron manifests itself in the absorption spectrum as a narrow feature to the red of the pure solid's vibron band. (C) 2003 American Institute of Physics.