2003ApJ...583L..43G

We report infrared absorption spectra of hydrogenated amorphous carbon (HAC) deposits prepared in the presence of deuterium. Spectra of D:HAC and DAC are characterized by the appearance of additional features near 2175 cm^–1 (4.6 µm) corresponding to stretching vibrations of CD_n groups. These are accompanied by a weakening of absorption in the CH_n_absorption bands throughout the infrared. Laboratory data suggest that it may be possible to detect deuterium fractionations X_D/H≥7.4x10^–3 in carbonaceous dust along the line of sight to Galactic center sources via absorption within the CD_nstretching band near 4.6 µm.