In Dutta and Del Barco, 1985, we can find Raman spectroscopic studies of zeolite framework. "Raman spectra of hydrated zeolite A completely exchanged with Li + , Na + , K + , Tl + , and NH4 + ions are reported in this paper. The emphasis has been on the high-frequency region between 300 and 1200 cm -1 , where the intramolecular modes of the aluminosilicate framework are expected. … In NH4-A, there is strong spectroscopic evidence for H-bond formation between the cation and the lattice oxygens". What is zeolite A? "Zeolite A, also known as LTA (Linde Type A), belongs to the family of aluminosilicate molecular sieves. It is characterized by the formula |(Na + 12(H2O)27|8[Al12Si12O48]8 which corresponds to its most common hydrated sodium form (International Zeolite Association -IZA)" (Julbe & Drobek, 2016). Zeolite A is a synthetic zeolite (for a discussion of natural and synthetic materials, see ). In the Zeolite A, we have Na, Al, Si, O and H as in natrolite. Dutta and Del Barco do not consider the OH-stretching region of Raman spectra.