Combination bands of the N2O trimer involving the intermolecular modes in the 2260 cm−1 region

Three new N2O trimer combination bands are observed in the region of the N2O ν1 fundamental. A band at 2269.4 cm−1 is reasonably strong and has b-type rotational structure. A weaker band, at 2253.7 cm−1, also has b-type rotational structure, but appears to be heavily perturbed. A third band, at 2255.5 cm−1, is weak and unperturbed but has a- and c-type transitions. Each band involves the sum of one of the three previously observed intramolecular trimer vibrations (N–N stretch of N2O) plus an intermolecular vibration (van der Waals stretch or bend), but there are 27 such possible combinations. Possible assignments of the three observed bands are discussed.