Infrared spectra of the Ne2-N2O, Ar2-N2O trimers

► Spectra of Ar2-N2O and Ne2-N2O are studied in the infrared region. ► A tunable quantum cascade laser is used to probe the expansion gas. ► The Q-branch of Ar3-N2O is tentatively assigned. ► Vibrational shifts for Nen-N2O and Arn-N2O are examined as a function of n. ► While the vibrational shifts for Nen-N2O is linear, Arn-N2O is blue shifted compared to the linear prediction.