Vibration modes of cryogenically H-implanted germanium in the specific case of cryogenic implantation were detected by Fourier transform IR spectroscopy. Multiple internal reflection apparatuses were used; this optical configuration allowed enough sensitivity to detect small absorption bands. By making an analogy with the "well-known" silicon modes, hydrogenated interstitial and multivacancy defects and hydrogen-terminated GeH2 were identified. The peaks at 1840 cm(-1) (1844 cm(-1) after annealing) and 1850 cm(-1) (1858 cm(-1) after annealing) can be attributed to IHx modes in germanium, those at 1850 cm(-1) (1858 cm(-1) after annealing) and 1821 cm(-1) (1828 cm(-1) after annealing) to IxH2, those at 1921 cm(-1) (1928 cm(-1) after annealing) to V2H, and those at 1948 cm(-1) to GeH2.