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Phosphorus-31 nuclear magnetic resonance observes spin-one-half phosphorus-31. An system can show a two-phosphorus doublet and a one-phosphorus triplet; three inequivalent mutually coupled phosphorus sites can each give a doublet of doublets in the first-order limit.
Boron-11 nuclear magnetic resonance probes boron environments. Rapid exchange can average inequivalent sites into one resonance; slow exchange reveals distinct sites. Quadrupolar relaxation and line broadening can complicate integration.
Chemical exchange in NMR interconverts environments during the observation. Fast exchange relative to their frequency difference produces averaged shifts; slow exchange resolves separate sites. A single peak alone does not prove a single static geometry.
NMR methods selecting slowly relaxing coherence components through interference between relaxation mechanisms. Appropriate labelling and field conditions extend measurements to larger assemblies.
Evolution of nuclear-spin populations and coherences toward equilibrium. Different relaxation measurements report different aspects of molecular motion.
Additional nuclear relaxation associated with a paramagnetic centre. With appropriate controls, its distance dependence constrains molecular arrangement and transient contacts.
NMR measurements on immobilized or slowly moving samples, using approaches such as decoupling, sample alignment or magic angle spinning to manage anisotropic interactions.
Transfer of polarization from electron spins to nuclei to enhance NMR sensitivity. Added radicals and low-temperature conditions can alter spectral resolution and the states sampled.
A detection probe with cooled electronic components to reduce noise and improve sensitivity. The sample need not itself be cooled to the electronics temperature.
Imaging based on spatial encoding of nuclear magnetic resonance signals. Acquisition and reconstruction choices determine which physical contrasts can be measured.
The timescale relevant to resolving exchange between resonance frequencies. Fast and slow are relative to the frequency separation and measurement, not absolute labels for molecular motion.
Nuclear magnetic resonance using lithium isotopes. Lithium-6 has spin 1 and a small quadrupole moment, often giving narrower aggregate resonances than lithium-7.
Correlation spectroscopy: a two-dimensional proton NMR experiment whose cross peaks identify scalar-coupled proton pairs. Overlap can prevent a unique letter-by-letter assignment.
Heteronuclear multiple-bond correlation: an experiment commonly detecting proton-carbon scalar coupling across two or three bonds. Occasional longer-range peaks, missing peaks and intensity variations require cautious interpretation.
A polarization-transfer carbon NMR experiment giving opposite phases to CH-two versus CH/CH-three signals in its usual convention; nonprotonated carbons are absent. Combined with other spectra it distinguishes methylene, methyl/methine and quaternary sites.
The decay timescale of the local magnetic-field fluctuations that relax a nuclear spin. Its relation to a tracer jump waiting time depends on geometry and the microscopic stochastic model.
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact