The NMR signal can subsequently be obtained by chemically breaking the molecular symmetry
or by applying radiofrequency pulses.
Among the topics are the physical basis of the NMR experiment, proton chemical shifts and spin-spin coupling constants as functions of structure, the influence of molecular symmetry
and chirality on proton magnetic resonance spectra, carbon-13 NMR spectroscopy, selected heteronuclei, and NMR of partially oriented molecules and solid-state NMR.
They cover the theory itself, topological chirality and molecular symmetry
, DNA topology, applications in physics, how topology is used in DNA nanotechnology, and the statistical and energetic properties of knots and their relation to molecular biology.
The presence of the fourth chapter, a review of molecular symmetry
, is questioned even by the author in the preface, but it is better present than absent, despite the minimal reference to it in later chapters.
He has had a major impact on spectroscopy through his books Molecular Symmetry
and Spectroscopy, co-authored with Per Jensen and Computational Molecular Spectroscopy, co-edited with Jensen.
16]O, a slightly bigger molecule that has no special molecular symmetry
and two molecules in the asymmetric unit, the agreement was less good .
where [theta] is the average angle between the chain axis and the molecular symmetry
axis, D is the dichroic ratio, which is the ratio between the absorbance of a particular band along the symmetry axis and the absorbance perpendicular to the symmetry axis.
In view of such molecular symmetry
requirements, says Bredas, the approach of Ashwell and his colleagues "does indeed seem heretical.
It provides information on functional groups, crystal forms, hydrogen bonding, orientation, conformation, molecular symmetry
, and other characteristics of large and small molecules.
His topics include molecular symmetry
, matrix representation of groups, quantum mechanics and group theory, atomic, rotational and vibrational spectrometry, light scattering and the Raman effect, and electronic spectroscopy of diatomics.
The internal conversion processes predominantly affect quantum yield of fluorescein through changes in molecular symmetry