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| Author(s): |
Márcio Fernando Cobo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2013-12-02 |
| Examining board members: |
Eduardo Ribeiro de Azevêdo;
Wilson Barros Júnior;
Hellmut Eckert;
Gustavo Alberto Monti;
José Fábian Schneider
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| Advisor: | Eduardo Ribeiro de Azevêdo |
| Abstract | |
In the present work we explore the use of Solid State Nuclear Magnetic Resonance (NMR) pulse sequences which use the heteronuclear dipolar magnetic coupling to study local rotations of molecular groups in the intermediate-regime of motion, testing them in standard samples in order to verify their efficiency. Simultaneously, numerical simulations and analytical calculations were performed to understand the experimental artifacts observed in these new pulse sequences. The first proposal, based on using Hartmann-Hahn matching profiles obtained by using the Cross Polarization transfer (CPMAS) under Lee-Goldburg homonuclear decoupling (LG), utilizing the heteronuclear dipolar interaction as probe of the molecular motion. The second proposal consists in a variation of DIPSHIFT and Time Constant recDIPSHIFT pulse sequences, dubbed T2 - recDIPSHIFT, whereby, in favorable conditions, it is possible to quantify molecular dynamic parameters of systems weakly coupled by heteronuclear dipolar interaction or to probe small-amplitude molecular motions. Finally, we proposed a new analytical method to describe Separated Local Field experiments (SLF), based upon the Anderson-Weiss approximation. We demonstrate the accuracy of the method comparing the Time Constant recDIPSHIFT curves for several rates and geometries of motion obtained by the analytical approximation and exact calculation, besides an experimental test has been performed in a model sample. (AU) | |
| FAPESP's process: | 08/11675-0 - NMR methods for studying soft materials: application to eletroluminescent polymers and intercalation nanocomposites |
| Grantee: | Márcio Fernando Cobo |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |