the sample and from changing back and front side of the film [81]. Regarding
fluorescence emitted by s-PS upon irradiation [82], it is difficult to analyze the origin
of the chiral components of the emitted light, since from CD experiments it is shown
that transmitted light is highly circularly polarized. We observe that the sign of the
CPL band is opposite with respect to CD absorption. This is compatible with the
interpretation that fluorescence emission at 320 nm from s-PS exhibits circularly
polarized components undergoing also different transmissions through the sample
(note that excitation light has quite lower wavelength to avoid superposition). The
observation of chiral components of emitted light (Fig. 10.13b), paralleling the
observation of chiral transmission (Fig. 10.13a), suggests a possible use of these
films to obtain chiral light from emission by (achiral) fluorophores, thus avoiding the
need of inducing chirality on the fluorophore.
With a very simple experiment, we showed how a fluorescent solution, placed
before the optically active s-PS film, can be used to obtain emitted light with highly
chiral components: left and right circularly polarized components of fluorescence are
differently “filtered” by the dichroic s-PS films. In particular, we measured the
circularly polarized components of light emitted by a fluorescein solution or a
Fig. 10.13 CD spectra (a) and CPL spectra (b) (obtained upon 265 nm excitation) of extruded s-PS
films, after sorption/desorption of (R)-carvone (red curve) and (S)-carvone (blue curve); emission of
fluorescein solution (exc. 450 nm) and quinine solution (exc. 365 nm): the emitted light is “filtered”
through s-PS film sorbed/desorbed with (R)- and (S)-carvone (c); geometry illustrated in (d). See
Ref. [81]
242
G. Longhi and S. Abbate
fluorescence emitted by s-PS upon irradiation [82], it is difficult to analyze the origin
of the chiral components of the emitted light, since from CD experiments it is shown
that transmitted light is highly circularly polarized. We observe that the sign of the
CPL band is opposite with respect to CD absorption. This is compatible with the
interpretation that fluorescence emission at 320 nm from s-PS exhibits circularly
polarized components undergoing also different transmissions through the sample
(note that excitation light has quite lower wavelength to avoid superposition). The
observation of chiral components of emitted light (Fig. 10.13b), paralleling the
observation of chiral transmission (Fig. 10.13a), suggests a possible use of these
films to obtain chiral light from emission by (achiral) fluorophores, thus avoiding the
need of inducing chirality on the fluorophore.
With a very simple experiment, we showed how a fluorescent solution, placed
before the optically active s-PS film, can be used to obtain emitted light with highly
chiral components: left and right circularly polarized components of fluorescence are
differently “filtered” by the dichroic s-PS films. In particular, we measured the
circularly polarized components of light emitted by a fluorescein solution or a
Fig. 10.13 CD spectra (a) and CPL spectra (b) (obtained upon 265 nm excitation) of extruded s-PS
films, after sorption/desorption of (R)-carvone (red curve) and (S)-carvone (blue curve); emission of
fluorescein solution (exc. 450 nm) and quinine solution (exc. 365 nm): the emitted light is “filtered”
through s-PS film sorbed/desorbed with (R)- and (S)-carvone (c); geometry illustrated in (d). See
Ref. [81]
242
G. Longhi and S. Abbate