Electron Paramagnetic Resonance Examination of Free Radical Formation in Salicylic Acid and Urea Exposed to UV Irradiation

<div>The effect of microwave power (<svg height="12.5794pt" id="M50" style="vertical-align:-3.29107pt" version="1.1" viewbox="-0.0498162 -9.28833 35.4405 12.5794" width="35.4405pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H795L470 145L347 650H176L170 622C268 613 275 606 244 503L190 322C150 188 132 126 118 91C102 50 80 33 18 28L12 0H245L251 28C175 35 170 48 174 93C177 128 191 180 220 284L292 542H294C331 392 383 150 409 4H432L774 555H776L714 137C700 40 694 34 612 28L606 0H868L874 28C793 34 784 37 797 137L849 533C859 612 863 616 956 622L962 650Z" id="g113-78"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="985" vert-adv-y="985"></glyph.data></g><g transform="matrix(.013,0,0,-0.013,12.807,0)"><path d="M368 703H309L44 -163H104L368 703Z" id="g113-48"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="412" vert-adv-y="412"></glyph.data></g><g transform="matrix(.013,0,0,-0.013,18.168,0)"><path d="M962 650H795L470 145L347 650H176L170 622C268 613 275 606 244 503L190 322C150 188 132 126 118 91C102 50 80 33 18 28L12 0H245L251 28C175 35 170 48 174 93C177 128 191 180 220 284L292 542H294C331 392 383 150 409 4H432L774 555H776L714 137C700 40 694 34 612 28L606 0H868L874 28C793 34 784 37 797 137L849 533C859 612 863 616 956 622L962 650Z" id="g113-78"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="985" vert-adv-y="985"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,30.388,3.132)"><path d="M452 282C452 397 389 451 302 451C268 451 227 441 188 422C95 377 24 281 24 154C24 65 70 -12 173 -12C240 -12 297 16 342 52C418 113 452 201 452 282ZM359 282C359 163 308 66 247 39C237 35 225 32 212 32C151 32 114 79 114 157C114 301 180 380 223 398C240 405 250 408 265 408C315 408 359 369 359 282Z" id="g50-112"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="476" vert-adv-y="476"></glyph.data></g></svg>) on amplitudes (<svg height="8.68572pt" id="M51" style="vertical-align:-0.0498209pt" version="1.1" viewbox="-0.0498162 -8.6359 9.2729 8.68572" width="9.2729pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M686 28C612 35 607 44 591 112C563 234 541 360 519 489L489 666L457 658L147 121C100 40 89 36 24 28L17 0H240L250 28C168 34 159 41 190 101L262 237H482C495 180 503 137 510 91C517 47 514 35 441 28L433 0H677L686 28ZM475 280H285L429 541H431L475 280Z" id="g113-66"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="703" vert-adv-y="703"></glyph.data></g></svg>) of the EPR spectra of UV irradiated urea during (a) 15 minutes, (b) 30 minutes, (c) 45 minutes, and (d) 60 minutes. <svg height="8.68572pt" id="M52" style="vertical-align:-0.0498209pt" version="1.1" viewbox="-0.0498162 -8.6359 12.9526 8.68572" width="12.9526pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H795L470 145L347 650H176L170 622C268 613 275 606 244 503L190 322C150 188 132 126 118 91C102 50 80 33 18 28L12 0H245L251 28C175 35 170 48 174 93C177 128 191 180 220 284L292 542H294C331 392 383 150 409 4H432L774 555H776L714 137C700 40 694 34 612 28L606 0H868L874 28C793 34 784 37 797 137L849 533C859 612 863 616 956 622L962 650Z" id="g113-78"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="985" vert-adv-y="985"></glyph.data></g></svg>: microwave power used during the measurement and <svg height="11.927pt" id="M53" style="vertical-align:-3.291101pt" version="1.1" viewbox="-0.0498162 -8.6359 17.2114 11.927" width="17.2114pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H795L470 145L347 650H176L170 622C268 613 275 606 244 503L190 322C150 188 132 126 118 91C102 50 80 33 18 28L12 0H245L251 28C175 35 170 48 174 93C177 128 191 180 220 284L292 542H294C331 392 383 150 409 4H432L774 555H776L714 137C700 40 694 34 612 28L606 0H868L874 28C793 34 784 37 797 137L849 533C859 612 863 616 956 622L962 650Z" id="g113-78"></path><glyph.data ascent="3473" descent="-2876" horiz-adv-x="985" vert-adv-y="985"></glyph.data></g><g transform="matrix(.0091,0,0,-0.0091,12.22,3.132)"><path d="M452 282C452 397 389 451 302 451C268 451 227 441 188 422C95 377 24 281 24 154C24 65 70 -12 173 -12C240 -12 297 16 342 52C418 113 452 201 452 282ZM359 282C359 163 308 66 247 39C237 35 225 32 212 32C151 32 114 79 114 157C114 301 180 380 223 398C240 405 250 408 265 408C315 408 359 369 359 282Z" id="g50-112"></path><glyph.data ascent="3443" descent="-2856" horiz-adv-x="476" vert-adv-y="476"></glyph.data></g></svg>: total microwave power produced by klystron (70 mW).</div>

International Journal of Photoenergy

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Figure 6

Figure 6: Electron Paramagnetic Resonance Examination of Free Radical Formation in Salicylic Acid and Urea Exposed to UV Irradiation 