Fundamental infrared absorption of H2 in solid Kr and of D2 in solid argon

The fundamental infrared absorption band of H2(D2) has been studied in the dilute solid solutions H2–Kr and D2–Ar, and the results are compared with previous data for H2–Ar. The spectrum consists of combination tones of molecular and lattice transitions; the lattice transition frequencies are (112, 22), (106, 16), and (79, 22) cm−1 for H2–Ar, H2–Kr, and D2–Ar, respectively. The previous assignment of the intense higher-frequency transition to the localized vibration of the impurity molecule on a substitutional lattice site is confirmed. The weaker lower-frequency transition is evidently due to an impurity-induced phonon transition of the host lattice.