The Molecular Surface Structure of Ammonium and Potassium Dinitramide: A Vibrational Sum Frequency Spectroscopy and Quantum Chemical Study.

Journal article, 2011

Vibrational sum frequency spectroscopy (VSFS) and quantum chem. modeling were employed to investigate the mol. surface structure of ammonium and potassium dinitramide (ADN and KDN) crystals. Identification of key vibrational modes was made possible by performing d. functional theory calcns. of mol. clusters. The surface of KDN was found to be partly covered with a thin layer of the decompn. product KNO3, which due to its low thickness was not detectable by IR and Raman spectroscopy. In contrast, ADN exhibited an extremely inhomogeneous surface, on which polarized dinitramide anions were present, possibly together with a thin layer of NH4NO3. The intertwined use of theor. and exptl. tools proved indispensable in the anal. of these complex surfaces. The exptl. verification of polarized and destabilized dinitramide anions stresses the importance of designing surface-active polymer support, stabilizers, and/or coating agents, in order to enable environmentally friendly ADN-based solid-rocket propulsion. [on SciFinder(R)]