Propagation and Termination Kinetics of Cross-Linking Photopolymerizations Studied Using Electron Paramagnetic Resonance Spectroscopy in Conjunction with Near IR Spectroscopy

2005 ◽  
Vol 38 (16) ◽  
pp. 6954-6964 ◽  
Author(s):  
Kathryn A. Berchtold ◽  
Theodore W. Randolph ◽  
Christopher N. Bowman
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Ir Spectroscopy ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Cross Linking ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Near Ir ◽  
Electron Paramagnetic ◽  
Kinetics Of

Characterization of titanium dopants in sodium alanate by electron paramagnetic resonance spectroscopy

2005 ◽  
Vol 20 (12) ◽  
pp. 3265-3269 ◽  
Author(s):  
Meredith T. Kuba ◽  
Sandra S. Eaton ◽  
Christine Morales ◽  
Craig M. Jensen
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Epr Spectra ◽  
Minor Amount ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Dehydrogenation Kinetics ◽  
Electron Paramagnetic ◽  
Kinetics Of

Electron paramagnetic resonance (EPR) spectra were obtained for samples of Ti-doped NaAlH4 subjected to different numbers of cycles of dehydrogenation/re-hydrogenation. Ti is observed to evolve from its initial Ti(III) state through a series of Ti(0) species during the first 5 cycles. Although the conversion of Ti(III) to Ti(0) occurs much more readily for TiCl3-doped samples than those prepared with TiF3, in both cases the evolution of Ti follows the same sequence that involves 3 distinguishable Ti(0) species and ends in the predominance of the same single Ti(0) species. The spectrum of a sample of NaAlH4 containing 2 mol% of cubic Al3Ti is distinctly different than any of those observed for the Ti(0) species that arise during the hydrogen cycling of the hydride. The major changes in the nature of the predominant Ti species have little if any effect on the dehydrogenation kinetics, which strongly suggests that the profoundly enhanced hydrogen cycling kinetics of Ti-doped NaAlH4 are due to a Ti species present in only a relatively minor amount.

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