Conformational flexibility of nitroxide biradicals determined by X-band PELDOR experiments
| Autor: | Olav Schiemann, Dominik Margraf, Andriy Marko, Thomas F. Prisner, Bela E. Bode |
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| Rok vydání: | 2007 |
| Předmět: |
Nitroxide mediated radical polymerization
Chemistry Biophysics Analytical chemistry X band Resonance Condensed Matter Physics Molecular physics Spectral line Magnetic field law.invention Amplitude modulation law Frequency offset Physical and Theoretical Chemistry Electron paramagnetic resonance Molecular Biology |
| Zdroj: | Molecular Physics. 105:2153-2160 |
| ISSN: | 1362-3028 0026-8976 |
| DOI: | 10.1080/00268970701724982 |
| Popis: | PELDOR (pulsed electron–electron double resonance) experiments have been performed at X-band (9 GHz) frequencies on a linear and a bent nitroxide biradical. All PELDOR time traces were recorded with the pump frequency νB set at the center of the nitroxide spectra to achieve maximum pumping efficiency, while the probe frequency νA was stepped between a frequency offset ΔνAB = νA − νB of +40 to +80 MHz. The modulation frequencies and the damping of the oscillations change as a function ΔνAB, whereas the modulation depth λ for our investigated systems was only very slightly altered. This can be explained by the selection of different orientations of nitroxide radicals with respect to the external magnetic field as a function of frequency offset. Quantitative simulations of the PELDOR time traces could be achieved for both molecules and for all offset frequencies using a simple geometric model, described by a free rotation of the nitroxide radical around its acetylene bond and a single bending mode of the int... |
| Databáze: | OpenAIRE |
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