Time-resolved ESR investigation on energy transfer processes in Nafion photochemistry

详细信息	查看全文 | 推荐本文 |

• 作者：Fosca Conti^a ; ^{fosca.conti@unipd.it} ; Enrico Negro^a ; Vito Di Noto^a ; Gordon Elger^b ; Thomas Berthold^c ; Stefan Weber^c
• 关键词：Polymer electrolyte ; Nafion membrane ; ESR spectroscopy ; Electron spin polarization ; Mobile excited triplet state ; Energy transfer
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 期刊代码：42_03603199
• 类别：ch
• 出版时间：April, 2012
• 卷：37
• 期：7
• 页码：6317-6325
• 文件大小：781 K

摘要

A solid film of Nafion has been prepared on the inner wall of a quartz tube. After pulsed photoexcitation, time-resolved electron spin resonance (TR-ESR) spectra have been recorded in the temperature range of 290-15聽K. The spectra exhibit strongly electron-spin polarized signals in full absorption arising from the excited triplet state of Nafion. The absence of any resolved spectral features and the unusual narrowing of the TR-ESR signal linewidth with decreasing temperature are discussed in terms of the spin Hamiltonian of an excited triplet state with dynamic dipole-dipole interactions between the two unpaired electron spins. The existence of a triplet-triplet energy transfer process is considered, and a prominent role of hydrogen bonds of the surrounding water network is suggested. Finally, the time evolutions of the TR-ESR signals have been analysed, and the corresponding decay parameters have been obtained at low temperatures. Our results provide insight on the role of water as a medium for the conductivity mechanism in Nafion membranes.