|take a look
at INFM microspheres!
the home page of the INFM facility for non-linear spectroscopy and imaging
in molecular biophysics.
The project has been funded by the INFM in 1999 and after a first period
of construction and test of the basic configuration it
is now open for the INFM users.
This page gives references and information for possible applications
and projects and calls for possible users.
The high spatial localization of the two-photon excitation is exploited
to obtain 3-D images of thick samples with no bleaching of the out of focus
regions of the sample. The use of long wavelengths gives further advantages
due to the low scattering of the excitation.
Though the excitation is obtained through the absorption of two photons
at a time, the emission properties are mostly unaffected with respect to
the usual single photon excitation. This allows to perform studies of lifetime
decays for molecules that cannot easily studied by single photon excitation.
Parallel to the lifetime studies we can measure the decay of the anisotropy
of the fluorescence polarization. The use of two-photon excitation can
help in studying dim fluorescent proteins since the static anisotropy for
two-photon excitation is higher than the one usually obtained for single
We exploit the high spatial resolution available with two-photon excitation
to observe the fluorescence fluctuations. The minimum excitation volume
available is 0.1 femtoLiters.