Optical Properties of β-RDX Thin Films Deposited on Gold and Stainless Steel Substrates Calculated from Reflection–Absorption Infrared Spectra

• Published in: Applied spectroscopy Vol. 71; no. 8; pp. 1990 - 2000
• Main Authors: Ruiz-Caballero, José L., Aparicio-Bolaño, Joaquín A., Figueroa-Navedo, Amanda M., Pacheco-Londoño, Leonardo C., Hernandez-Rivera, Samuel P.
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01-08-2017
• Subjects: ν̃ LO; optical constants; Reflection–absorption infrared spectroscopy; transverse optical vibration; film thickness; RAIRS; FT-IR; ν̃ TO; Fourier transform infrared spectroscopy; longitudinal optical vibration; spin coating; ν̃LO; ν̃TO
• ISSN: 0003-7028; 1943-3530
• DOI: 10.1177/0003702817710248

The optical properties for crystalline films of the highly energetic material (HEM) hexahydro-1,3,5-trinitro-s-triazine, which is also known as RDX, deposited on gold (Au) and stainless steel (SS) substrates are presented. RDX has two important stable conformational polymorphs at room temperature: α-RDX and β-RDX. The optical properties obtained in the present work correspond to thin film samples of predominantly β-RDX polymorph. The infrared spectroscopic intensities measured showed significant differences in the β-RDX crystalline films deposited on the two substrates with respect to the calculated real part of refractive index. The β-RDX/Au crystalline films have a high dynamic response, which is characterized by the asymmetric stretching mode of the axial nitro groups, whereas for the β-RDX/SS crystalline films, the dynamic response was mediated by the –N-NO2 symmetric stretch mode. This result provides an idea of how the electric field vector propagates through the β-RDX crystalline films deposited on the two substrates.