Oxygen vacancies on Pd/TiO2 are detected at low pressures by ESR spectroscopy at ambient temperatures

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2022-1-01

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Üner, Deniz
Yarar, Melis

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All rights reserved.A low field benchtop electron spin resonance (ESR) (also referred to as electron paramagnetic resonance (EPR)) spectrometer is used to reveal paramagnetic centres such as oxygen vacancies and Ti+3 centres over 0.5%Pd/TiO2. The measurement was performed at room temperature after the sample was reduced in situ under mild hydrogen pressures and evacuated to P < 10–6 Torr. The measurement was possible due to a T1 compensation effect under vacuum: Correlation times at low pressures enabled sufficient line narrowing and detection of the ESR signal, justifying a method using benchtop spectrometers coupled to vacuum manifolds. The method justification was demonstrated using similar measurements performed on a reference compound, Mn(II) in plasticine: a measurement performed by saturation recovery technique revealed that T1 of the signal due to Mn(II) was smaller in vacuum than its atmosphere exposed counterpart. By applying vacuum, the ESR spectra of 0.5%Pd/TiO2 were collected at ambient temperatures, with features equivalent to the published data obtained at cryogenic temperatures.

Subject Keywords

low pressure ESR, room temperature electron paramagnetic resonance (EPR), Room temperature electron spin resonance (ESR), saturation-recovery CW-ESR

URI

https://hdl.handle.net/11511/101792

Journal

Turkish Journal of Chemistry

DOI

https://doi.org/10.55730/1300-0527.3416

Collections

Department of Chemical Engineering, Article

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Citation Formats

D. Üner and M. Yarar, “Oxygen vacancies on Pd/TiO2 are detected at low pressures by ESR spectroscopy at ambient temperatures,” Turkish Journal of Chemistry, vol. 46, no. 4, pp. 1081–1088, 2022, Accessed: 00, 2023. [Online]. Available: https://hdl.handle.net/11511/101792.