Accessing the Nitromethane (CH₃NO₂) Potential Energy Surface in Methanol (CH₃OH)–Nitrogen Monoxide (NO) Ices Exposed to Ionizing Radiation: An FTIR and PI-ReTOF-MS Investigation

Abstract

(D-)Methanol-nitrogen monoxide (CHOH/CDOH-NO) ices were exposed to ionizing radiation to facilitate the eventual determination of the CHNO potential energy surface (PES) in the condensed phase. Reaction intermediates and products were monitored via infrared spectroscopy (FTIR) and photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS) during the irradiation and temperature controlled desorption (TPD) phase, respectively. Distinct photoionization energies were utilized to discriminate the isomer(s) formed in these processes. The primary methanol radiolysis products were the methoxy (CHO) and hydroxymethyl (CHOH) radicals along with atomic hydrogen. The former was found to react barrierlessly with nitrogen monoxide resulting in the formation of cis- and trans-methyl nitrite (CHONO), which is the most abundant product that can be observed in the irradiated samples. On the other hand, the self-recombination of hydroxymethyl radicals yielding ethylene glycol (HO(CH)OH) and glycerol (HOCHCH(OH)CHOH) is preferred over the recombination with nitrogen monoxide to nitrosomethanol (HOCHNO).

Exploring the Photochemistry of Solid 1,1-Diamino-2,2-dinitroethylene (FOX-7) Spanning Simple Bond Ruptures, Nitro-to-Nitrite Isomerization, and Nonadiabatic Dynamics

“…Merging the experimental observations with electronic structure calculations suggests that for 355 nm, the nitro-tonitrite isomerization in FOX-7 represents the initial reaction pathway followed by O�NO bond rupture of the nitrite moiety to nitric oxide (NO). In contrast to previous decomposition studies in our laboratory at 5 K involving nitromethane (CH 3 NO 2 ) 76,78,79,81 and RDX, 34,35 no nitrogen dioxide (NO 2 ) was observed suggesting the absence of any C�NO 2 bond rupture process. The absence of the nitrogen dioxide channel is likely the result of the crystal structure of α-FOX-7 holding waved sheets of FOX-7 molecules linked by hydrogen bonding between oxygen atoms of the nitro group with hydrogen atoms of the amino group both inter-and intramolecularly.…”

Investigating the Photochemical Decomposition of Solid 1,3,5-Trinitro-1,3,5-triazinane (RDX)

“…62−64 Prominent bands at 2340, 2231, 2138, 2079, 1861, and 1756 cm −1 are assigned to carbon dioxide (CO 2 ), dinitrogen monoxide (N 2 O), carbon monoxide (CO), formyl radical (HCO), nitrogen monoxide (NO), and the nitrogen monoxide dimer ([NO] 2 ), respectively. 14,16,65 The observed vibrational features of these products are in excellent agreement with those reported by Alix et al after photodecomposition of RDX employing a broadband UV light. 16 An absorption feature at 1300 cm −1 is also observed (see Figure 2) which can be assigned to O−NO symmetric stretching mode of either dinitrogen trioxide (N 2 O 3 ) and/or nitrogen dioxide (NO 2 ).…”

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).…”