Biomedical Engineering Reference
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Figure 1.7
EffectsofdisorderontheCDspectraofnine-particlehelices.(a)
Calculated averaged CD spectra for the ideal helix and for three non-ideal
helices.Forthenon-idealhelices,theCDspectrawereaveragedoverasetof
trials.Overall,
80trialswithgeneratingrandompositionsofparticleswere
made. Inset: The model to scale. (b) Calculated CD spectra for randomized
positions of helically arranged NPs as a function of the trail number. Insets
show how the NP position fluctuations were introduced. Reprinted with
permission from SI of Ref. [42]. Copyright c
∼
2012, Rights Managed by
Nature Publishing Group.
the handedness of an incident light beam. Hence, it generates more
heat dissipation. In Fig. 1.8a, we show that a total CD signal can
be mathematically separated. The wavelength of a longitudinal
(
z
) mode is slightly longer than a transverse (
xz
) mode. At 522
nm, we observe negative maxima at the poles of the sphere in
Fig. 1.8c for a right-handed helix. At the poles, it indicates that
incident beams propagate along the axis of a helix. Therefore, a
right-handed
xy
-modeisslightlystrongerunderilluminationofRCP
light, contributing a negative CD signal to the total CD spectrum. At
552 nm, although there is no direct analogy between handedness of
thedipoleexcitationsandhandednessofthehelix,weobservedthat
theCDsignalflippedbetweenaright-handedhelixandaleft-handed
helixinthesimulationsreportedintheSIofRef.[42].Thisindicates
