|
Showing 1 - 7 of
7 matches in All Departments
This book provides an introduction to the understanding and use of
object-oriented methodologies for engineering problem solving with
a specific emphasis on analysis and design. (Object-oriented
programming is a general computer language methodology. The name
comes from the focus on describing problems in terms of objects,
both physical and conceptual).
In NMR, it is well-known that the chemical shift conveys structural
informa tion, e. g. a carbonyl carbon will have a resonance
frequency appreciably dif ferent from a methyl carbon, etc. The
relation between structure and chemical shift is mostly established
by empirical rules on the basis of prior experience. It is only
quite recently that the advent of both comparatively cheap comput
ing power and novel quantum chemistry approaches have provided
feasible routes to calculate the chemical shift at the ab initio
level for molecules of reasonable size. This raises the question
whether application of these novel theoretical concepts offers a
means of obtaining new structural information for the complex chain
molecules one deals with in polymer science. Solid state 13C-NMR
spectra of glassy amorphous polymers display broad, partially
structured resonance regions that reflect the underlying disorder
of the polymer chains. The chemical shift responds to the variation
of the ge ometry of the chain, and the broad resonance regions can
be explained by an inhomogeneous superposition of various chain
geometries (and thus chem ical shifts). In this review, we present
a novel approach to combine polymer chain statistical models,
quantum chemistry and solid state NMR to pro vide quantitative
information about the local chain geometry in amorphous polymers.
The statistical model yields the relative occurrence of the various
geometries, and quantum chemistry (together with a force field
geometry op timization) establishes the link between geometry and
chemical shift."
|
You may like...
Book Lovers
Emily Henry
Paperback
(4)
R275
R254
Discovery Miles 2 540
Goose
Laura Wall
Paperback
R100
R93
Discovery Miles 930
|
Email address subscribed successfully.
A activation email has been sent to you.
Please click the link in that email to activate your subscription.