Optimization of an absolute sensitivity in a glassy matrix during DNP-enhanced multidimensional solid-state NMR experiments

Hiroki Takahasni, Carlos Fernández de Alba, Daniel Lee, Vincent Maurel, Serge Gambarelli, Michel Bardet, Sabine Hediger, Anne-Laure Barra, Gaël De Paëpe

Research output: Contribution to journalArticlepeer-review

Abstract

Thanks to instrumental and theoretical development, notably the access to high-power and high-frequency microwave sources, high-field dynamic nuclear polarization (DNP) on solid-state NMR currently appears as a promising solution to enhance nuclear magnetization in many different types of systems. In magic-angle-spinning DNP experiments, systems of interest are usually dissolved or suspended in glass-forming matrices doped with polarizing agents and measured at low temperature (down to ∼100 K). In this work, we discuss the influence of sample conditions (radical concentration, sample temperature, etc.) on DNP enhancements and various nuclear relaxation times which affect the absolute sensitivity of DNP spectra, especially in multidimensional experiments. Furthermore, DNP-enhanced solid-state NMR experiments performed at 9.4 T are complemented by high-field CW EPR measurements performed at the same magnetic field. Microwave absorption by the DNP glassy matrix is observed even below the glass transition temperature caused by softening of the glass. Shortening of electron relaxation times due to glass softening and its impact in terms of DNP sensitivity is discussed.
Original languageEnglish
Pages (from-to)91-99
Number of pages9
JournalJOURNAL OF MAGNETIC RESONANCE
Volume239
DOIs
Publication statusPublished - Feb 2014

Keywords

  • Solid-state NMR
  • dynamic nuclear-polarization
  • High-field EPR
  • Glassy solution
  • Absolute sensitivity radio
  • Microwave absortion

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