Istituto Nazionale per
la Fisica della Materia
for multi-photon excitation
fluorescence spectroscopy
on biomolecules
Sezione B
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Istituto Nazionale per la Fisica della Materia |
for multi-photon excitation fluorescence spectroscopy on biomolecules |
Sezione B |
General Information |
Fluorescence correlation
spectroscopy allows to
-- measure the translational diffusion coefficient of macromolecules, -- count the number of fluorescent molecules under observation, -- measure the relative fluorescence yield of different molecules in a inhomogeneous solution and therefore discriminate the amount of each species. Fluorescence correlation spectroscopy is based on the measurement of fluctuations of the fluorescence. This fluctuation can be due to the diffusion of the fluorophore in the excitation volume or to a change of fluorescence quantum yield due to chemical reactions. In order to get information one must measure on few molecules at a time (of the order of 10 molecules). This is achieved by illuminating tiny volumes (of the order of 1 femtoliter = 1 mm3) that are available by employing two-photon excitation. In this facility Vexc=0.1 fL are routinely obtained. Analysis
of the fluctuations (correlation functions)
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| Biophysics
at
the university of Milano-Bicocca |
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