Publication | Open Access
Blue- and red-shifts of V<sub>2</sub>O<sub>5</sub>phonons in NH<sub>3</sub>environment by<i>in situ</i>Raman spectroscopy
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Citations
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References
2017
Year
A layer of ~30 nm V2O5/100 nm-SiO2 on Si was employed in the in situ Raman spectroscopy \nin the presence of NH3 effluent from a thermal decomposition of ammonium acetate salt with \nthe salt heated at 100 °C. When the layer is placed at 25 °C, we observe a reversible red-shift of \n194 cm−1 V2O5 phonon by 2 cm−1 upon NH3 gas injection to saturation, as well as a reversible \nblue-shift of the 996 cm−1 by 4 cm−1 upon NH3 injection. However when the sensing layer is \nplaced at 100 °C, the 194 cm−1 remains un-shifted while the 996 cm−1 phonon is red-shifted. \nThere is a decrease/increase in intensity of the 145 cm−1 phonon at 25 °C/100 °C when NH3 \ninteracts with V2O5 surface. Using the traditional and quantitative gas sensor tester system, we \nfind that the V2O5 sensor at 25 °C responds faster than at 100 °C up to 20 ppm of NH3 beyond \nwhich it responds faster at 100 °C than at 25 °C. Overall rankings of the NH3 gas sensing \nfeatures between the two techniques showed that the in situ Raman spectroscopy is faster in \nresponse compared with the traditional chemi-resistive tester. Hooke’s law, phonon confinement \nin ~51 nm globular particles with ~20 nm pore size and physisorption/chemisorption principles \nhave been employed in the explanation of the data presented.
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