Temperature‐dependent Raman study of H‐bonds and possible phase‐transition in LiHCOO·H2O

Polarized Raman spectra of single crystals of lithium formate monohydrate (LiHCOO·H2O) have been measured from 4.2 K to 320 K. In the high‐frequency region, the observed modes have been assigned and the water molecule vibrations identified. The crystallographic distances between the two oxygens involved in the two hydrogen bonds have been obtained from the frequencies of the stretching OH vibrations, and the corresponding O…︁O vibration frequencies have been predicted and identified in the low‐frequency region. Although the crystal is thought to be potentially ferroelectric, we have observed no evidence of any structural change or presence of a ‘soft’ phonon in the crystal in the temperature range studied. Our measurements in various configurations do not indicate the presence of any LOTO splittings or any hydrogen disorder in the crystal.