Vibrational relaxation of three-phonon bound states in crystal CO2

Vibrational lifetimes of three-photon bound states (triphonons) observed in the vibrational region 3ω2;(ω1 + ω2) of crystal CO2 have been measured in the temperature range 10–200 K. The relaxation is interpreted in terms of depopulation of excited levels and dephasing by low-frequency phonons. A comparison with results for biphonons in the Fermi resonance region 2ω2;ω1 is made and similarities are discussed.