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Dipartimento di Fisica e Scienze della Terra

Laboratory facilities

 

 

Our laboratories are equipped with steady state and time resolved spetroscopic methods which include UV-VIS spectrophotometers, FTIR,  fluorimeter, laser flash photolysis, Fuorescence Correlation Spectroscopy (FCS), time resolved photoacoustics and others.

 

Nanosecond laser flash photolysis

The lab is equipped with two nanosecond laser photolysis spectrometers with l

aser limited time resolution and absorbance changes detection in the range 400 nm - 1000 nm.

Excitation sources Continuum Surelite II -10 (10 Hz repetition rate, 355, 532, 1064 nm) Spectron Laser (1 Hz repetition rate, 355, 532, 1064 nm)

Transient absorption detection systems Single wavelength setup. 150W Xe arc lamp with monochromator (AMKO),  detection monochromator (after the sample holder, LOT-Oriel), 5 stages photomultiplier (Applied Photophysics), digital oscilloscope (LeCroy, 1GHz, 10 Gs/s).Time resolved spectra.75W Xe arc lamp, dual port monochromator/spectrograph with 5 stages photomultiplier (Applied Photophysics) and gated i-ccd (istar, Andor).

 

Image courtesy Zofia Gasik

 

CW laser photolysis

Photolysis setups exploit cw lasers: frequency doubled cw Nd:YAG laser (Laser Quantum, Manchester, UK 1 W at 532 nm); Air cooled multiline Ar ion laser (JDS Uniphase, 150 mW, all lines); HeNe laser (Uniphase, 633 nm, 30 mW); Diode laser (670 nm)

The cw pump beam is shuttered using an acousto optic modulator to achieve opne-close times in the hundred nanoseconds time range. For microsecond resolution, a mechanichal shutter (Uniblitz) is used instead. Split portions of the cw beams are also used for detecting the absorbance changes, monitored as the intensity of the transmitted light intensity through a preamplified photodiode.

 

 Image Cristiano Viappiani

 

Laser pH jump

The laser pH jump setup uses the third harmonic (355 nm) of a NdYAG laser to induce release of protons from a photoacid.The effects are detected as changes in absorption and/or fluorescence emission of the sample by means of cw lasers (Ar multiline 457-514 nm, HeNe).

 

Time resolved photoacoustics

We have two photoacoustic detection systems, manufactured by Quantum Northwest. Both rely on a piezoelectric V103 videoscan Panametrics detector with 1 MHz resonance frequency. A fully integrated TASC 300 system allows accurate temperature control and data acquisition and elaboration. A Flash 100 temperature controlled holder is also available. Excitation is provided by a nanosecond NdYAG laser Continuum Surelite II -10 (10 Hz repetition rate, 355, 532, 1064 nm) or Spectron Laser (1 Hz repetition rate, 355, 532, 1064 nm)

 

Fluorescence Correlation Spectroscopy

The MicroTime 200 fluorescence lifetime microscope system is a multi purpose instrument capable of measuring fluorescence lifetime and fluorescence correlation spectroscopy (FCS) with single molecule detection sensitivity. It contains the complete confocal optics (based on an Olympus IX70 inverted microscope) and electronics for recording virtually all aspects of the fluorescence dynamics of microscopic samples or femtoliter volumes. The microscope is equipped with a water immersion, high numerical aperture objective. Available excitations sources are picosecond diode lasers at 405nm, 475 nm, and 635 nm. The systems has two detection channels based on single photon counting avalanche photodiodes (SPADs).

 

Time Correlated Single Photon Counting 

Time Correlated Single Photon Counting (TCSPC) setup for determination of fluorescence decay lifetimes. The equipment uses a 365 nm picosecond LED with up to 10 MHz repetition rate and detection through a Peltier cooled photomultiplier for single photon counting. Emission wavelength is selectable through a 12” grating monochromator.