site splitting

https://doi.org/10.1351/goldbook.08678

Appearance of more than one band in the spectrum of a crystal when only one is seen in that of the gas, when this splitting is attributed to either the molecule lying on a crystal site of lower symmetry than that of the gaseous molecule or to molecules occupying more than one type of crystal site. See crystal field splitting.

Note: Site splitting arises from the static intermolecular forces in the crystal.

Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 763 (https://doi.org/10.1515/pac-2019-0203)