Spectroscopic Investigation of Nitric Acid Monohydrate

Philipp Baloh (1) , Hinrich Grothe (1) , Karin Whitmore (2) , Stewart F. Parker (3) , Beatriz Martín-Llorente (4) , Rafael Escribano (4)

1 Institute of Materials Chemistry
2 Universitaere Service-Einrichtung fuer Transmissionselektronenmikroskopie (USTEM)
3 RAL - STFC Rutherford Appleton Laboratory
4 Instituto de Estructura de la Materia

Vibrational spectroscopy, X-ray diffraction, and electron microscopy have been applied to investigate the crystallization of concentrated amorphous nitric acid (0.5 ≤ x ≤ 0.95). Crystalline nitric acid monohydrate (HNO3∙H2O) is the major hydrate phase detected together with traces of metastable nitric acid dihydrate (HNO3∙2H2O) and pure crystalline nitric acid. Nitric acid tetratohydrate (4HNO3∙H2O) was not achievable. The diffraction data show nitric acid monohydrate as a highly symmetrical structure, which bestows clearly laid out infrared, Raman and inelastic neutron scattering (INS) spectra. The low frequency region is still a matter of discussion since experiment and theory are not in accordance. The microscopic picture underlines the model character of nitric acid monohydrate, since the crystalline particles adopt a spherical shape, on various agglomeration stages, which minimizes the interference of scattering on the spectroscopic data.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Philipp Baloh, Hinrich Grothe, Karin Whitmore, Stewart F. Parker, Beatriz Martín-Llorente, et al.. Spectroscopic Investigation of Nitric Acid Monohydrate. Molecular Physics, 2011, pp.1. ⟨10.1080/00268976.2011.593571⟩. ⟨hal-00716636⟩