Hyper‐Raman spectroscopy of CeO2

Cerium dioxide (CeO2) belongs to the fluorite structure group (Oh5 point group) resulting in one Raman active T2g mode and two IR active T1u TO and LO modes. The T2g Raman band in CeO2 has been used to probe the symmetric Ce–O vibrational mode of different sized nanoparticulates. Far infrared studies of the Ce–O interactions are difficult to conduct because of low optical transmission, efficiency of the detector, and water absorption bands interfering with the measurements. The selection rules of hyper‐Raman spectroscopy (HRS) allow the study of IR bands in the far infrared spectral region, such as the motion of the Ce atoms. For the first time, HRS was used to investigate the T1u TO and LO IR modes in CeO2. The position and full‐width half‐maximum (FWHM) of the TO and LO bands in the HRS spectrum were used to investigate the spectral response in relation to particle size (i.e., phonon confinement). The investigation of CeO2 with HRS provides a research platform for future work in the study of ThO2, UO2, and PuO2 IR modes. The T2g Raman band in cerium dioxide (CeO2) has been used to probe the Ce–O motions of different sized nanoparticulates. The selection rules of hyper‐Raman spectroscopy (HRS) allow the study of IR bands in the far infrared spectral region, such as the motion of the Ce atoms. For the first time, HRS was used to investigate the T1u TO and LO IR modes in CeO2.