Electron Radiolysis of Ammonium Perchlorate: A Reflectron Time-of-Flight Mass Spectrometric Study

Abstract

Thin films of ammonium perchlorate (NHClO) were exposed to energetic electrons at 5.5 K to explore the radiolytic decomposition mechanisms. The effects of radiolysis were monitored on line and in situ via Fourier transform infrared spectroscopy (FTIR) in the condensed phase along with electron impact ionization quadrupole mass spectrometry (EI-QMS) and single-photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) during the temperature-programmed desorption (TPD) phase to probe the subliming molecules. Three classes of molecules were observed: (i) nitrogen bearing species [ammonia (NH), hydroxylamine (NHOH), molecular nitrogen (N), nitrogen dioxide (NO)], (ii) chlorine carrying molecules [chlorine monoxide (ClO), chlorine dioxide (ClO), dichlorine trioxide (ClO)], and (iii) molecular oxygen (O). Decay profiles of the reactants along with the growth profiles of the products as derived from the infrared data were fit kinetically to obtain a reaction mechanism with the initial steps involving a proton loss from the ammonium ion (NH) yielding ammonia (NH) and the decomposition of perchlorate ion (ClO) forming chlorate ion (ClO) plus atomic oxygen. The latter oxidized ammonia to hydroxylamine and ultimately to nitrogen dioxide. Molecular oxygen and nitrogen were found to be formed via recombination of atomic oxygen and multistep radiolysis of ammonia, respectively.

First identification of unstable phosphino formic acid (H2PCOOH)

“…The experiments were conducted in an ultrahigh vacuum (UHV) surface science machine operated at a base pressure of a few 10 −11 Torr. 6,[14][15][16][17][18] Binary ice mixtures of phosphine (PH 3 ) and carbon dioxide (CO 2 ), phosphine (PH 3 ) and [ 13 C]-carbon dioxide ( 13 CO 2 ), as well as phosphine (PH 3 ) and [ 18 O]-carbon dioxide (C 18 O 2 ) were prepared in separate experiments with thicknesses of 830 ± 50 nm at 5.5 ± 0.2 K. The non-equilibrium chemistry and bond-cleavage processes were stimulated by exposing these ices to energetic electrons for one hour at an average dose of 2.8 ± 0.6 eV per molecule. After the irradiation, the ices were heated at a rate of 1 K min −1 to 320 K (temperature programmed desorption; TPD).…”

“…Having established the formation of a new molecule with the molecular formula PH 3 CO 2 (78 amu) along with its 13 C and 18 O substituted counterparts, we are shifting our attention now to the identification of the PH 3 CO 2 product isomer(s). This objective is achieved by selectively photoionizing specific structural isomers based on their ionization energies.…”

Recovery of Ammonium Perchlorate from Obsolete Ammunition and Its Application in Synthesis of Lithium Perchlorate

“…Characteristic peaks that appeared at 3250–3700 cm −1 and 1403 cm −1 belong to stretching and bending vibrations of ammonia, respectively [26]. A peak located at 627 cm −1 corresponds to stretching vibrations of the ClO 4 − coordinate covalent bonds, while a broad peak around 1090 cm −1 is from the asymmetric stretching vibration of ClO 4 − [27]. Before purification, we observed multiple peaks resulting from impurities (AP−O), but after purification, only broad ammonia bands were detected, which indicated the removal of bulk impurities.…”

On the formation and the isomer specific detection of methylacetylene (CH3CCH), propene (CH3CHCH2), cyclopropane (c-C3H6), vinylacetylene (CH2CHCCH), and 1,3-butadiene (CH2CHCHCH2) from interstellar methane ice analogues

“…The FTIR was operated in absorption-reflection-absorption mode at a reflection angle of 451 to the substrate normal in the mid-IR region from 5000 to 500 cm À1 with a resolution of 4 cm À1 at 2 minute intervals, which allowed collection of 30 spectra during the one hour of irradiation with 5 keV electrons. [91][92][93][94] Following the irradiation phase the ice was held isothermal at 5 K for one hour. Next, the substrate was heated to 300 K through a controlled ramp rate of 0.5 K min À1 (temperature programmed desorption; TPD).…”