Detection of Hydrogen in Bulk and Thin Film Silicon Dioxide by Hydrogen Nuclear Magnetic Resonance

1992 ◽  
Vol 284 ◽  
Author(s):  
D. H. Levy ◽  
K. K. Gleason
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Silicon Dioxide ◽  
Hydrogen Content ◽  
Solid State Nmr ◽  
Fused Silica ◽  
Nmr Data ◽  
Silica Material ◽  
Deep Ultraviolet ◽  
Nuclear Magnetic

ABSTRACTHydrogen is a common impurity in silicon dioxide (SiO2) which can influence its optical and electronic properites. Here, nuclear magnetic resonance (NMR) is applied to study of hydrogen in these materials, despite their relatively low hydrogen content. We present results for bulk fused silica as well as thermally grown films of SiO2 on silicon. These experiments demonstrate the potential of solid state NMR for studying low hydrogen content film systems. In bulk fused silica, we have observed that although the majority of hydrogen is isolated, a small number of centers exist involving adjacent silanol pairs. These pairs react during high temperature annealing as well as during deep ultraviolet irradiation. Furthermore, the presence of these centers is related to the susceptibility of fused silica to radiation damage. The results obtained on the fused silica material are compared to SiO2 films on silicon. The NMR spectra and relaxation associated with thick (>1μm) wet SiO2 films are similar to those for the fused silica while the NMR data for thinner oxide more closely resembles those of surface water on silica gel.

scholarly journals Solid-state nuclear magnetic resonance characterization of the second generation of the UEC family of molecular sieves

2019 ◽  
Author(s):  
Heitor Secco Seleghini ◽  
Heloise de Oliveira Pastore ◽  
Fábio Aurélio Bonk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Molecular Sieves ◽  
Solid State Nmr ◽  
Second Generation ◽  
3D Structures ◽  
Nuclear Magnetic

This work reports the characterization using solid-state NMR of the second generation of the UEC family of molecular sieves, such generation is composed by two tridimensional silicoaluminophosphates synthesized from a layered aluminophosphate (AlPO-CJ70). The 3D structures are analogous to SAPO-5 (UEC-4) and SAPO-15 (UEC-5), both were characterized using multinuclear solid-state NMR, 27Al-MQ-MAS and 29Si{27Al} TRAPDOR.

scholarly journals Recent Advances in Solid-State Nuclear Magnetic Resonance Spectroscopy

2018 ◽  
Vol 11 (1) ◽  
pp. 485-508 ◽  
Author(s):  
Sharon E. Ashbrook ◽  
John M. Griffin ◽  
Karen E. Johnston
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Solid State Nmr ◽  
Spectral Lines ◽  
Atomic Scale ◽  
Resonance Spectroscopy ◽  
Diverse Range ◽  
Nuclear Magnetic

The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local atomic-scale environment offers great potential for the characterization of a diverse range of solid materials. Despite offering more information than its solution-state counterpart, solid-state NMR has not yet achieved a similar level of recognition, owing to the anisotropic interactions that broaden the spectral lines and hinder the extraction of structural information. Here, we describe the methods available to improve the resolution of solid-state NMR spectra and the continuing research in this area. We also highlight areas of exciting new and future development, including recent interest in combining experiment with theoretical calculations, the rise of a range of polarization transfer techniques that provide significant sensitivity enhancements, and the progress of in situ measurements. We demonstrate the detailed information available when studying dynamic and disordered solids and discuss the future applications of solid-state NMR spectroscopy across the chemical sciences.

Recent Contributions of Nuclear Magnetic Resonance in Organocatalysis Mechanism Elucidation

2019 ◽  
Vol 7 (1) ◽  
pp. 7-22
Author(s):  
Gustavo Senra Gonçalves De Carvalho ◽  
Álisson Silva Granato ◽  
Pedro Pôssa De Castro ◽  
Giovanni Wilson Amarante
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Reaction Mechanisms ◽  
Solid State Nmr ◽  
High Field ◽  
Isotopic Effect ◽  
Reaction Monitoring ◽  
Real Time Identification ◽  
Non Destructive ◽  
Nuclear Magnetic

Background: Nuclear Magnetic Resonance (NMR) is one of the most employed techniques in structural elucidation of organic compounds. In addition to its use in structural characterization, it has been widely employed in the investigation of reaction mechanisms, especially those involving catalysis. Objective: In this review, we aim to provide recent examples of the interface of NMR and organocatalysis reaction mechanism. Methods: Selected examples of different approaches for mechanism elucidation will be presented, such as isotopic effect, catalyst labelling and online reaction monitoring. A discussion involving the use of solid-state NMR will also be disclosed. Conclusion: NMR consists of a non-destructive technique, extremely useful in the real-time identification of intermediates in crude reaction mixtures. With the advent of two-dimensional experiments and high field NMR spectrometers, the reports of studies involving mechanistic elucidation were greatly enhanced. In this context, nowadays NMR appears as a powerful tool for the comprehension of reaction mechanisms, including the possibility of the proposal of unknown reaction mechanisms within organocatalysis.

15N and 13C nuclear magnetic resonance of deoxydinucleotide monophosphates. II. Protonation of the homo dimers deoxycytidylyl-(3′,5′)-deoxycytidine, thymidylyl-(3′,5′)-thymidine, and deoxyadenylyl-(3′,5′)-deoxyadenosine in dimethyl sulfoxide

1990 ◽  
Vol 68 (11) ◽  
pp. 2033-2038 ◽  
Author(s):  
Giovanna Barbarella ◽  
Massimo Luigi Capobianco ◽  
Luisa Tondelli ◽  
Vitaliano Tugnoli
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Dimethyl Sulfoxide ◽  
Phosphate Group ◽  
Nmr Data ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Nuclear Magnetic

The preferential protonation sites of the homo dimers deoxycytidylyl-(3′,5′)-deoxycytidine, thymidylyl-(3′,5′)-thymidine, and deoxyadenylyl-(3′,5′)-deoxyadenosine were established by nitrogen-15 and carbon-13 NMR in dimethyl sulfoxide, in the presence of varying amounts of CF3COOH. The nitrogen-15 NMR data show that in d(CpC) the capability of the two N3 nitrogens to accept the proton is slightly different. In d(TpT) and d(ApA) the protonation of the phosphate group leads to significant variations of the chemical shift of the carbons adjacent to phosphorus. Keywords: deoxydinucleotides, protonation, 15N and 13C NMR.

Perfluoroalkyl- and fluoroalkyl- complexes of rhodium(III)

1976 ◽  
Vol 54 (13) ◽  
pp. 2077-2084 ◽  
Author(s):  
Howard C. Clark ◽  
Kenneth J. Reimer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Infrared Spectra ◽  
Oxidative Addition ◽  
Far Infrared ◽  
Addition Reactions ◽  
Nmr Data ◽  
Far Infrared Spectra ◽  
Nuclear Magnetic

A series of perfluoroalkyl (Rf—) and fluoroalkyl (RfCH2—) complexes of rhodium(III) have been prepared by oxidative addition reactions of RfI and RfCH2I (Rf = CF3, C2F5 and C3F7) with trans-RhClCO(PMe2Ph)2. The reaction of CF3I with trans-RhClCO(PMePH2)2 gave RhClI(CF3)CO(PMePh2)2 but no reaction was observed with CF3CH2I. The trans stereochemistry of addition has been assigned to all complexes by nuclear magnetic resonance measurements and the comparison of the far-infrared spectra to those of some bromo compounds: RhBrI(CF3)CO(PMe2Ph)2 and RhBrI(C3F7CH2)CO(PMe2Ph)2. Both 1H and 19F nmr data are presented and discussed.

Case study of quantification of oil viscosity and saturation in complex reservoirs using advanced nuclear magnetic resonance log interpretation techniques

2011 ◽  
Vol 51 (2) ◽  
pp. 725
Author(s):  
Adrian Manescu ◽  
Keith Boyle
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Clay Content ◽  
Hydrocarbon Exploration ◽  
Fluid Viscosity ◽  
Oil Viscosity ◽  
Porosity Distribution ◽  
Nmr Data ◽  
Log Interpretation ◽  
Nuclear Magnetic

In the hydrocarbon exploration process, after a prospect has been identified and an exploration well has been drilled, a critical piece of information is the oil type. Earlier wireline or while-drilling well-logging technologies provided rock properties and saturation information, but relied on expensive sampling and testing to determine oil properties. This weakness was overcome through the introduction of nuclear magnetic resonance (NMR) logs that can provide formation properties—lithology-independent porosity, porosity distribution, permeability, etcetera—and information about the reservoir fluid viscosity. NMR data were recently acquired in complex, high-clay content, low-salinity oil reservoirs. Traditional petrophysical interpretations throughout these reservoirs were confronted with a complex lithology—comprising feldspathic litharenites and volcanic lithic components—high clay content and low formation water salinity, of 3-4 Kppm NaCl eq. This extended abstract shows how acquisition and interpretation of NMR data not only provided porosity and porosity distribution, but also identified oil viscosity across the logged intervals. Advanced NMR log interpretation techniques (2D-NMR maps of diffusion (D) versus T2, int) were used to identify oil NMR signal. This technique produced a continuous profile of diffusion and intrinsic T2 distribution maps. Once the oil NMR signal was identified, an estimation of the oil viscosity was also possible because D and T2, int are related with viscosity. Several available correlations have been used and results were comparable with production data.

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