An Experimental Technique for Studying the Infrared Spectrum of Chemisorbed Compounds

Guilbault, George G.; Scheide, Eugene P.; Das, J.

doi:10.1080/00387016808049958

Cited by 18 publications

(11 citation statements)

References 5 publications

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“…In addition to the prominent phosphonate P–O–C stretching modes at 995 and 1020 cm –1 , we observe significant signal intensity from propene’s CH 2 wagging mode (912 cm –1 ) and the bending modes of acetylene and ethylene (730 cm –1 and 949 cm –1 , respectively). All peaks referenced herein are consistent with those reported for the corresponding molecules in the gas phase. ,− CO is also observed, but this is difficult to uniquely assign to either DIMP or HOPG ablation. Additionally, other small product peaks are observed in the spectra beyond those highlighted in Figure , but we were not able to clearly establish their identities using FTIR alone.…”

Section: Results and Discussionsupporting

confidence: 79%

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

et al. 2019

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We present work detailing the destruction of the nerve agent simulant diisopropyl methylphosphonate (DIMP) via rapid laser heating under atmospheric conditions. Following Nd:YAG laser ablation of liquid DIMP deposited on a graphite substrate, both parent and product fragments are transmitted via capillary from an atmospheric chamber to a vacuum chamber containing a high-resolution mass spectrometer. This allows for real-time measurements of product distributions under a variety of temperature and atmospheric conditions. Ex situ Fourier transform infrared (FTIR) spectroscopy analysis of the same chamber contents provides complementary information about product identities and fragmentation pathways. Results demonstrate that product distributions depend on heating rate, surface temperature, and atmospheric oxygen content. In the destruction of the DIMP, the relative yields of alkene products depends significantly on laser power; smaller products are relatively more abundant at higher ablation temperatures. We also show that in the absence of atmospheric oxygen, the concentration of oxygenated products decreases sharply relative to alkene and alkane products. This suggests that under high-temperature conditions, atmospheric oxygen is incorporated directly into the products of the fragmented simulant. This project extends significantly our understanding of the fundamental chemistry of these dangerous compounds under atmospheric and rapidly changing thermal conditions. The results have critical implications for the development of effective chemical warfare agent decontamination and destruction strategies.

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Section: Results and Discussionsupporting

confidence: 79%

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

et al. 2019

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“…A representative spectrum of a 27-layer DIMP film is shown in Figure , with the three characteristic regions most frequency referenced herein (POC, PO, and CH stretches) highlighted in color. The respective peak assignments are consistent with expectations and values previously reported in the literature. ,− …”

Section: Methodssupporting

confidence: 91%

“…The original peaks associated with pristine DIMP are clearly observed to decrease in intensity upon exposure. In the P–O–C region (Figure a), it is the 995 and 1020 cm –1 signals that decay; these peak locations match reported values for the asymmetric and symmetric P–O–C stretches. ,− This decay corresponds to reactive destruction of these modes . Concurrent with this destruction, however, new intensity is observed between 1030 and 1100 cm –1 .…”

Section: Resultssupporting

confidence: 71%

Oxidative Destruction of Multilayer Diisopropyl Methylphosphonate Films by O(³P) Atomic Oxygen

2017

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We present work detailing the oxidative destruction of the nerve agent simulant diisopropyl methylphosphonate (DIMP) with O(P) using time-resolved, in situ reflection absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). Thermally annealed DIMP films deposited on Au(111) are observed to react upon exposure to a supersonic beam containing O(P) with average translational energies of 0.12 eV. The reaction is initiated by a hydrogen abstraction from one of three possible sites on DIMP, and then progresses through various secondary reactions with resultant hydroxyl radicals, carbon-centered DIMP-derived radicals, and nondissociated O in the beam. These reactions are accompanied by uptake of oxygen into the film, leading to new hydrogen bonding with the DIMP phosphoryl group. The generated product also presents greater thermal stability than pristine DIMP, suggesting the formation of a distribution of oligomeric and polymeric products. As reactivity is observed to decrease upon continued O(P) exposure, this product likely forms a protective layer at the vacuum-film interface, hindering destruction of thicker films. Importantly, the rate of reaction and general reactivity trends are the same between DIMP and the smaller simulant dimethyl methylphosphonate (DMMP). The comparable reaction rates of the two molecules coupled with oxygen's inability to erode thick films all the way down to the substrate have specific implications for the development of oxidation-based decontamination strategies for these and other organophosphates in the solid phase. The findings presented in this paper add significant new fundamental understanding of the oxidative chemistry of such species, knowledge needed in order to develop efficacious nerve agent decontamination strategies as well as the refinement of existing models for the dispersal, adsorption, persistence, and destruction of organophosphates in the environment.

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“…4. 38,43 There is no PQO stretch visible for Zn-TTP-PO 3 H 2 , which is likely due to strong intermolecular interactions similar to those observed for the carboxylic acid. 4a), the ester group has a prominent n as (CH 3 ) peak at 1433 cm À1 .…”

Section: Characterization Of Sensitizers On Tiomentioning

confidence: 91%

“…4b), the spectrum of Zn-TTP-PO(OEt) 2 shows the PQO stretch at 1230 cm À1 , and also has characteristic phosphonate ester bands for P-O-C at 1053 cm À1 and 1026 cm À1 . 38,43 There is no PQO stretch visible for Zn-TTP-PO 3 H 2 , which is likely due to strong intermolecular interactions similar to those observed for the carboxylic acid. A broad shoulder on the 1000 cm À1 band is characteristic of P-O-H stretching.…”

Section: Characterization Of Sensitizers On Tiomentioning

confidence: 91%

Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells

Brennan

Portolés

Liddell

et al. 2013

Phys. Chem. Chem. Phys.

149

185

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A tetra-arylporphyrin dye was functionalized with three different anchoring groups used to attach molecules to metal oxide surfaces. The physical, photophysical and electrochemical properties of the derivatized porphyrins were studied, and the dyes were then linked to mesoporous TiO2. The anchoring groups were β-vinyl groups bearing either a carboxylate, a phosphonate or a siloxy moiety. The siloxy linkages were made by treatment of the metal oxide with a silatrane derivative of the porphyrin. The surface binding and lability of the anchored molecules were studied, and dye performance was compared in a dye-sensitized solar cell (DSSC). Transient absorption spectroscopy was used to study charge recombination processes. At comparable surface concentration, the porphyrin showed comparable performance in the DSSC, regardless of the linker. However, the total surface coverage achievable with the carboxylate was about twice that obtainable with the other two linkers, and this led to higher current densities for the carboxylate DSSC. On the other hand, the carboxylate-linked dyes were readily leached from the metal oxide surface under alkaline conditions. The phosphonates were considerably less labile, and the siloxy-linked porphyrins were most resistant to leaching from the surface. The use of silatrane proved to be a practical and convenient way to introduce the siloxy linkages, which can confer greatly increased stability on dye-sensitized electrodes with photoelectrochemical performance comparable to that of the other linkers.

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An Experimental Technique for Studying the Infrared Spectrum of Chemisorbed Compounds

Cited by 18 publications

References 5 publications

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

Oxidative Destruction of Multilayer Diisopropyl Methylphosphonate Films by O(³P) Atomic Oxygen

Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells

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An Experimental Technique for Studying the Infrared Spectrum of Chemisorbed Compounds

Cited by 18 publications

References 5 publications

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

Rapid Laser-Induced Temperature Jump Decomposition of the Nerve Agent Simulant Diisopropyl Methylphosphonate under Atmospheric Conditions

Oxidative Destruction of Multilayer Diisopropyl Methylphosphonate Films by O(3P) Atomic Oxygen

Comparison of silatrane, phosphonic acid, and carboxylic acid functional groups for attachment of porphyrin sensitizers to TiO2 in photoelectrochemical cells

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Oxidative Destruction of Multilayer Diisopropyl Methylphosphonate Films by O(³P) Atomic Oxygen