Dipartimento di Chimica IFM, Università di Torino, and NIS Centre of Excellence, via P. Giuria 7, 10125 Torino, Italy.
Phys Chem Chem Phys. 2010 Sep 28;12(36):10933-41. doi: 10.1039/c0cp00084a. Epub 2010 Jul 26.
Continuous wave (CW) and pulse electron paramagnetic resonance in a variant of hyperfine sublevel correlation spectroscopy (HYSCORE) were used for obtaining structural information concerning speciation and local environment of alien Cu(2+) and native O(2)(-) ions encaged in copper doped nanoporous 12CaO.7Al(2)O(3) (mayenite). The samples were prepared by a solid-state reaction and characterized by means of XRD, SEM, and Raman techniques. X-Band CW-EPR spectra showed that three different Cu(2+) species together with paramagnetic extraframework O(2)(-) anions were present in the mayenite sample, whereas extraframework OH(-) anions were revealed by Raman spectroscopy. (27)Al HYSCORE provided evidence for the interaction of Cu(2+) ions with the mayenite framework. Superhyperfine interaction of the Cu(2+) ions with proximal (d(Cu-OH) = 2.4 A) and distal (d(Cu-OH) = 5.0 A) OH(-) anions, located in the same and the nearby cage, respectively, was resolved by means of (1)H HYSCORE spectra. A different situation held for the encaged O(2)(-) radicals found to be sitting on the Ca(2+) ions. They exhibited only a weak superhyperfine interaction of 1 MHz with the (27)Al(3+) framework ions.
连续波 (CW) 和脉冲电子顺磁共振在超精细亚层相关光谱 (HYSCORE) 的变体中被用于获取有关在铜掺杂纳米多孔 12CaO.7Al2O3 (镁铝尖晶石) 中笼状的外来 Cu(2+) 和本征 O(2)(-) 离子的形态和局部环境的结构信息。样品通过固态反应制备，并通过 XRD、SEM 和拉曼技术进行了表征。X 波段 CW-EPR 光谱表明，镁铝尖晶石样品中存在三种不同的 Cu(2+) 物种以及顺磁的外框架 O(2)(-) 阴离子，而外框架 OH(-) 阴离子则通过拉曼光谱揭示。(27)Al HYSCORE 提供了 Cu(2+) 离子与镁铝尖晶石骨架相互作用的证据。通过 (1)H HYSCORE 光谱，分辨了 Cu(2+) 离子与近邻 (d(Cu-OH) = 2.4 A) 和远邻 (d(Cu-OH) = 5.0 A) OH(-) 阴离子的超精细相互作用，分别位于同一和附近的笼中。对于被发现位于 Ca(2+) 离子上的笼状 O(2)(-) 自由基，情况则不同。它们仅与 (27)Al(3+) 骨架离子表现出 1 MHz 的弱超精细相互作用。
