A comparative study on the growth and characterization of nonlinear optical amino acid crystals: l-Alanine (LA) and l-alanine alaninium nitrate (LAAN)

A comparative study on the properties of l-alanine and LAAN crystals has been made and discussed. It may be concluded that the protonation of the amino group in the l-alanine molecule is the key factor in increasing the relative SHG efficiency of LAAN. The protonation is justified by the crystal structure analysis, FTIR and photoluminescence studies. The factor group vibrations are compared and found that there is an increase in vibrational modes of LA when reacted with nitric acid forming LAAN.