The system of CH3I adsorbed on submonolayer, monolayer, and multilayer thin films of D2O on Cu(110) has been studied by measuring the time of flight (TOF) distributions of the desorbing CH3 fragments after photodissociation using linearly polarized λ = 248 nm light. For multilayer D2O films (2-120 ML), the photodissociation is dominated by neutral photodissociation via the "A-band" absorption of CH3I. The polarization and angle dependent variation in the observed TOF spectra of the CH3 photofragments find that dissociation is largely via the (3)Q0 excited state, but that also a contribution via the (1)Q1 excitation can be identified. The photodissociation results also indicate that the CH3I adsorbed on D2O forms close-packed islands at submonolayer coverages, with a mixture of C-I bond axis orientations. For monolayer and submonolayer quantities of D2O we have observed a contribution to CH3I photodissociation via dissociative electron attachment (DEA) by photoelectrons. The observed DEA is consistent with delocalized photoelectrons from the substrate causing the observed dissociation- we do not find evidence for an enhanced DEA mechanism via the temporary solvation of photoelectrons in localized states of the D2O ice.
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http://dx.doi.org/10.1063/1.4770225 | DOI Listing |
Phys Chem Chem Phys
January 2025
Department of Physics, University of Northern BC, Canada.
Photofragment translational spectroscopy has been used to characterize the energetics and the cross sections for photodissociation of CHI and CFI adsorbed on thin films of a variety of aromatic molecules, initiated by near-UV light. Thin films (nominally 10 monolayers) of benzene, five substituted benzenes and two naphthalenes have been employed to study systematic changes in the photochemical activity. Illumination of these systems with 248 nm light is found to result in a dissociation process for the CHI and CFI mediated by initial absorption in the aromatic thin film, followed by electronic energy transfer (EET) to the dissociating species.
View Article and Find Full Text PDFInorg Chem
December 2024
National Co-Innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China.
Nitrogen-rich small molecules are frequently doped into porous materials to enhance their iodine adsorption properties. To explore how imidazole confinement in metal-organic frameworks (MOFs) affects iodine adsorption, we obtained a UiO-66-based composite by embedding imidazole in UiO-66 pores via solid-phase adsorption (Im@UiO-66). Characterization confirmed that imidazole was successfully confined within the UiO-66 pores, with each unit of UiO-66 accommodating up to 27 imidazole molecules.
View Article and Find Full Text PDFAnal Chem
October 2024
College of Chemistry, Chemical Engineering and Environment, Minnan Normal University, Zhangzhou 363000, China.
J Hazard Mater
September 2024
School of National Defence Science & Technology, Southwest University of Science and Technology, Mianyang 621010, PR China. Electronic address:
J Hazard Mater
July 2024
National Co-Innovation Center for Nuclear Waste Disposal and Environmental Safety, Southwest University of Science and Technology, Mianyang 621010, China; Tianfu Institute of Research and Innovation, Southwest University of Science and Technology, Chengdu 610299, China; State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China. Electronic address:
Effective capture of radioactive iodine from nuclear fuel reprocessing is of great importance for public safety as well as the secure utility of nuclear energy. In this work, a hydrophobic nanosheet silicalite-1 (NSL-1) zeolite with an adjustable size was developed for efficient iodine (I) and methyl iodide (CHI) adsorption. The optimized all-silica zeolite NSL-1 exhibits an excellent I uptake capacity of 553 mg/g within 45 min and a CHI uptake capacity of 262 mg/g within 1 h.
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