Skip to main content Accessibility help
×
Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-26T02:17:59.274Z Has data issue: false hasContentIssue false

4 - Experimental methods

Published online by Cambridge University Press:  19 October 2009

Vincent J. McBrierty
Affiliation:
Trinity College, Dublin
Get access

Summary

The study of solid polymers by NMR requires spectrometers with rather special characteristics. In this chapter we outline their principal features and describe a number of experiments that explore different aspects of the way in which resonant nuclei behave: measurements on 1H, 2H and 13C predominate. The low natural abundance of 13C and the unusually broad deuterium linewidths pose special technical problems.

Although the emphasis throughout is on pulse methods of excitation, it is important to recall that, for the determination of spectra, the only method widely used for many years was the field or frequency sweep technique, often referred to as continuous wave (CW) excitation. In this method an rf field of small amplitude is applied continuously and either the B0 field or the rf frequency is swept across the resonance absorption. Because of the very different requirements of high-resolution measurements in liquids and the broad, low-resolution spectra characteristic of abundant spins in solids (for example 1H and 19F), quite different spectrometer designs evolved for these two areas. The so-called ‘broadline’ CW spectrometer used field modulation techniques which generate the derivative of the absorption lineshape. Corrections were often necessary to account for the fact that component lines of the spectrum with substantially different spin—lattice relaxation characteristics and linewidths responded differently to the imposed modulation.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure [email protected] is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×