Measurement of the Energy Dependence of X-ray-Induced Decomposition of Potassium Chlorate.

Abstract

We report the first measurements of the X-ray induced decomposition of KClO3 as a function of energy in two experiments. KClO3 was pressurized to 3.5 GPa and irradiated with monochromatic synchrotron X-rays ranging in energy from 15 to 35 keV in 5 keV increments. A systematic increase in the decomposition rate as the energy was decreased was observed, which agrees with the 1/E(3) trend for the photoelectric process, except at the lowest energy studied. A second experiment was performed to access lower energies (10 and 12 keV) using a beryllium gasket; suggesting an apparent resonance near 15 keV or 0.83 Ǻ maximizing the chemical decomposition rate. A third experiment was performed using KIO3 to ascertain the anionic dependence of the decomposition rate, which was observed to be far slower than in KClO3, suggesting that the O-O distance is the critical factor in chemical reactions. These results will be important for more efficiently initiating chemical decomposition in materials using selected X-ray wavelengths that maximize decomposition to aid useful hard X-ray-induced chemistry and contribute understanding of the mechanism of X-ray-induced decomposition of the chlorates.

High-pressure structural behaviour of HoVO4: combined XRD experiments andab initiocalculations

“…One possibility is that partial decomposition could be trigger by x-ray absorption which could induce photoelectric processes leading to the dissociation of V 2 O 5 units from HoVO 4 . Such a decomposition has been recently observed in ternary oxides in HP experiments [40], in particular when x-rays with wavelengths larger than 0.6 Å are used. After the study of Pravica et al [40], we considered that in HoVO 4 the x-ray induced decomposition may be caused by the dissociation of V 2 O 5 from the starting material.…”

“…This dissociation has been suggested to be associated to a bond-related resonance of x-ray standing waves generated within the unit-cell [40]. According with this hypothesis, decomposition would be maximized for x-ray wavelengths close to half of the V-O bond length.…”

Exploring the properties of MTO4 compounds using high‐pressure powder x‐ray diffraction

“…Another interesting observation is that a partial decomposition of HoVO 4 was observed when a large x‐ray wavelength is used for the experiments. This fact was also observed in other oxides, being proposed that it could be triggered by x‐ray absorption . The equations of state (EOS) of the different structures of HoVO 4 have been accurately determined from experiments .…”

High-pressure studies with x-rays using diamond anvil cells

“…Irradiating a liquid mixture of O2 and N2, contained in a DAC under pressure with a 10.2 keV synchrotron radiation, caused dissociation of O2 and N2 molecules and induced a chemical reaction to form NO2 + NO3 -, an ionic phase of N2O5 [583]. In a study of the x-ray induced decomposition of KClO3 and KIO3 [626], the decomposition rate is found to be energy dependent, with an apparent resonance near 15 keV, maximizing the chemical decomposition rate. The resonance is likely related to the O-O distance in x-ray induced reactions.…”