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Title: Optically enhanced nuclear cross polarization in acridine-doped fluorene

Abstract

The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemicalmore » shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.« less

Authors:
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (USA)
OSTI Identifier:
5193797
Report Number(s):
LBL-14644
ON: DE82018801
DOE Contract Number:
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of document are illegible
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; FLUORENE; POLARIZATION; ACRIDINES; MONOCRYSTALS; POWDERS; SPIN; SPIN ORIENTATION; TENSORS; ANGULAR MOMENTUM; AROMATICS; AZINES; CONDENSED AROMATICS; CRYSTALS; HETEROCYCLIC COMPOUNDS; HYDROCARBONS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORIENTATION; PARTICLE PROPERTIES; PYRIDINES; 400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)

Citation Formats

Oshiro, C.M. Optically enhanced nuclear cross polarization in acridine-doped fluorene. United States: N. p., 1982. Web. doi:10.2172/5193797.
Oshiro, C.M. Optically enhanced nuclear cross polarization in acridine-doped fluorene. United States. doi:10.2172/5193797.
Oshiro, C.M. 1982. "Optically enhanced nuclear cross polarization in acridine-doped fluorene". United States. doi:10.2172/5193797. https://www.osti.gov/servlets/purl/5193797.
@article{osti_5193797,
title = {Optically enhanced nuclear cross polarization in acridine-doped fluorene},
author = {Oshiro, C.M.},
abstractNote = {The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.},
doi = {10.2172/5193797},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1982,
month = 6
}

Technical Report:

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  • Pulsed Nuclear Magnetic Resonance (NMR) has been applied to: (1) Measurements of the prinicpal components of the proton shielding tensors of the hydrides of zirconium chloride and zirconium bromide. Multiple-Pulse techniques have been used to remove static homonuclear dipolar coupling. The anisotropies and isotropic shifts of these tensors have been used to infer the possible locations of the hydrogen within the sandwich-like layers of these unusual compounds. (2) Studies of the oscillatory transfer of magnetic polarization between /sup 1/H and /sup 29/Si in substituted silanes. The technique of J Cross Polarization has been used to enhance sensitivity. The /sup 29/Simore » NMR shifts of -Si-O- model compounds have been investigated as a possible probe for future studies of the environment of bound oxygen in coal-derived liquids. (3) Measurements of the aromatic fraction of /sup 13/C in whole coals. The techniques of /sup 1/H-/sup 13/C Cross Polarization and Magic-Angle Spinning have been used to enhance sensitivity and remove shift anisotropy. Additional topics described are: (4) Calculation and properties of the broadened lineshape of the shileding Powder Pattern. (5) Calculation of the oscillatory transfer of magnetic polarization for an I-S system. (6) Numerical convolution and its uses. (7) The technique of digital filtering applied in the frequency domain. (8) The designs and properties of four NMR probe-circuits. (9) The design of a single-coil double-resonance probe for combined Magic-Angle Spinning and Cross Polarization. (10) The designs of low Q and high Q rf power amplifiers with emphasis on the rf matching circuitry.« less
  • Cross polarization magic-angle spinning /sup 13/C NMR spectra of all of the samples studied are collected in this report. Because of the widely-varying characteristics of the spectra obtained on this project (e.g. different linewidths, aliphatic/aromatic ratios, aromatic chemical shift anisotropies as manifested in spinning sidebands) and because of the progress of research during the period of the project, the spectra were partitioned for analysis in various ways. In preparing this final report, we have standardized the partitioning into two alternate schemes. In one scheme the spectrum is divided arbitrarily into an aliphatic region (95 ppM to -10 ppM) and anmore » aromatic region (the remainder of the spectrum, including spinning sidebands. This partitioning gives the f/sub a/' values (apparent aromatic fraction) reported in the tables. As the only significant sidebands from MAS come from the aromatic resonances, this (and the second) approach should account for the sidebands properly as aromatic intensity. In the second partitioning scheme the spectra are divided into three regions (I, II, III). Region II spans from 105 ppM to 70 ppM, region III from 70 ppM to -10 ppM and Region I is the remainder of the spectrum (aromatic/olefinic resonances, including their spinning sidebands). The expected error ranges given with the f/sub a/' values in the tables of this report are estimates based on experience with numerous similar samples and several replicate determinations. 33 figures, 5 tables.« less