Photo-thermal Decomposition of HNS Surface by 532 nm Laser Irradiation: Spectral and Quantitative Analysis using In-Situ XPS- Quadrupole MS Technique

A novel approach for studying the photo-thermal decomposition of HNS (2,2',4,4',6,6'-hexanitrostilbene) at 532 nm induced by a 10-nanosecond (ns) laser pulse is described. In this method, in-situ X-ray photoelectron spectrometer (XPS) - laser-quadrupole mass spectrometer on-line equipment was designed. New peaks at binding energies of 399.7 eV in the N 1s XPS spectrum and 288.6 eV in the C 1s spectrum showed that nitro-nitrite isomerization with subsequent release of NO occurs in the laser-induced decomposition of HNS. A new peak at 30 m/z in the mass spectrum is also associated with the mechanism of the nitro-nitrite isomerization of the HNS molecule, with subsequent release of NO. Quantum chemistry calculation results are in good agreement with the experimental results. We attribute this laser-induced decomposition as a photo-thermal decomposition for the high temperature rise due to the laser irradiation.