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Advanced Optical Spectroscopy and Microscopy

optics

The Advanced Optical Facility combines a broad range of ultrafast instruments suitable for the characterization of optical and optoelectronic properties of hard, soft or biological materials functioning in ex situ and in operando conditions. Among the various available techniques, the facility hosts several ultrafast pump-probe spectrometers and microscopes, some with single nanostructure sensitivity, nonlinear and hyperspectral microscopies covering a broad spectral range spanning from UV to VIS and NIR. The facility entertains a large variety of research projects including photophysics and photochemistry of low dimensional semiconductor materials, characterization of quantum materials down to 4k, plasmonic materials, materials for light harvesting and energy storage. In operando techniques are available to allow users the study of materials in various environments, optoelectronic characterization and spectroelectrochemistry with single nanostructure sensitivity.

Spectroscopy

  • Ultrafast Pump-Probe Transient Absorption Spectroscopy with broadband femtosecond and nanosecond probing covering UV, VIS and NIR regions.
  • Time-Resolved Photoluminescence Spectroscopy covering UV, VIS and NIR.
  • Advanced data analysis methods, including single decay and global fits using a variety of kinetic models, antibunching for single photon sources, fluorescence correlation spectroscopy and burst integrated fluorescence lifetime analysis.

Microscopy

  • Time and Spectrally Resolved Confocal Fluorescence Imaging and Probing with single nanoparticle sensitivity and low temperature cryostat down to 4K.
  • Time and Spectrally Resolved Electroluminescence Imaging and Probing.
  • Confocal Hyperspectral Dark Field/ Bright Field/Fluorescence Imaging with single nanostructure sensitivity.
  • Hyperspectral High-Speed Laser Scanning Confocal Fluorescence Imaging.
  • Non-Linear Imaging: Second Harmonic Generation and Two-Photon Photoluminescence.
  • Scanning Photocurrent Imaging.

Spectrometers

  • Ultrafast Pump-Probe Transient Absorption Spectrometer
    Femto-and Nanosecond Transient Absorption Spectrometer (Ultrafast Systems, Helios, EOS), combined with tunable femtosecond pump pulses from TOPAS OPA. Spectral transients can be recorded with broadband 100 fs (0 - 3 ns range) or 500 ps (0 – 50 ms range) probe pulses in the UV/VIS (370 - 850 nm) or NIR (850 - 1600 nm).
    Good for: ultrafast kinetics of charge and energy transfer materials, 2D materials, inorganic materials, quantum dots, polymers, proteins.
  • Ultrafast Pump-Probe Transient Upconversion Spectrometer
    Fluorescence Upconversion Spectrometer (Ultrafast Systems, Halcione), for measuring ultrafast emission processes in the visible and NIR (400 - 1600 nm) with a time resolution of ~ 200 fs over 0 - 3 ns range.
    Good for: ultrafast kinetics of charge and energy transfer materials, 2D materials, inorganic materials, quantum dots, polymers, proteins.
  • Time Resolved Fluorescence Lifetime Spectrometer
    Fluorescence Lifetime Spectrometer (Picoquant FT 200) for time-resolved emission probing in UV-VIS-NIR (400-850nm, 950-1450nm). Uses a Hamamatsu microchannel plate-PMT detector for UV-VIS (25 ps response) and a Hamamatsu InGaAs PMT for NIR (400-ps response). Liquid N2 cryostat available for low temperature experiments. Polarization and anisotropy attachments included. Capable of recording fluorescence decays, time-resolved anisotropy and time-resolved emission spectra.
    Good for: ultrafast kinetics of charge and energy transfer materials, 2D materials, inorganic materials, quantum dots, conductive polymers, proteins, organic dyes.

Optical Microscopes

  • Time and Spectrally Resolved Confocal Photoluminescence and Electroluminescence Microscope
    Olympus IX81 inverted microscope with objective scanning stage, various high NA objective lenses, Si-based single photon counting detectors (400-1100nm range) and InGaAs photon counting detector (900nm-1650nm) for time-resolved PL imaging and probing, including single photon source characterization. Uses an Acton SP2750-Pixis100 spectrograph/CCD system for micro-PL spectroscopy (400-1100nm range). Equipped with a micro-cryostat for low temperature (4.5K) imaging. Available laser excitations are pulsed 442nm, 532nm at various repetition rates. For time and spectrally resolved electroluminescence measurements, a 600 ps impulse current generator is used.
  • Confocal Hyperspectral Dark Field/Bright Field/Fluorescence Microscope
    Nikon Eclipse T2 inverted microscope with long working distance objectives and laser based LED white light source, Acton SP500-Pixis100 spectrograph/CCD camera (400nm-1100nm) for recording scattering and fluorescence spectra, spectroelectrochemistry attachment, bright field imaging, chirality and polarization modes. Good for: scattering spectra of plasmonic noble metal nanoparticles, confocal absorption spectra of 2D materials, reflectivity measurements, spectroelectrochemistry of plasmonic nanoparticles, photocatalytic plasmonic samples.
  • Confocal Hyperspectral High-Speed Laser Scanning Fluorescence Microscope
    Leica TCS SP5 commercial inverted laser-scanning confocal fluorescence microscope (video rate) for fluorescence, transmission and reflection imaging (400-800nm range). Capable of FRET, FRAP, FCS, HyperSpectral Imaging, micro PL spectroscopy using CW laser with lines in the 457-632 nm range, FLIM, SHG and Two-Photon Imaging with a MaiTai femtosecond broadband laser (710nm-990nm). Good for: biological sample imaging including cells, quantum dots, proteins.
  • Stationary Fluorescence Spectrometer/Fluorimeter
    Horiba Nanolog Fluorescence Spectrometer for UV-VIS-NIR (400-1750nm). Records both emission and excitation spectra, 2D emission-excitation maps, stationary anisotropy. Cuvettes and thin film sample support are available. Liquid N2 cryostat available for low temperature experiments. Polarization and anisotropy attachments.
    Good for: organic and inorganic fluorescent materials, quantum dots, conductive polymers, protein, organic dyes.
  • Scanning Photocurrent Imaging Microscope
    Home built instrument based on an Olympus IX81 inverted microscope and three lasers (488nm, 561nm, 632nm), long working distance high NA lens, large area scanning, photodetector for reflection imaging.
    Good for: FET characterization of quantum dots, conductive polymers, 2D materials, carrier diffusion length.

Ultrafast Optical Spectroscopy

Contact: Mircea Cotlet

Our facility houses state-of-the-art high-power kilohertz and megahertz femtosecond laser systems including regenerative amplifiers. These are interfaced with optical parametric amplifiers to allow generation of sub 100 femtosecond pulses in the ultraviolet, visible, and infrared regions of the spectrum. These laser systems are coupled to a series of user-friendly time-resolved and nonlinear optical techniques, providing users with a broad suit of tools for characterizing the optical properties of their materials, including:

Femtosecond Transient Absorption Spectroscopy

This is a commercial broadband transient absorption spectrometer (Helios, Ultrafast Systems) with approximately 100 fs time resolution in a time window of 0 - 7 ns. In this technique, the samples are optically "pumped" using a tunable (240 - 2600 nm) femtosecond laser pulse and "probed" for changes in transmission using a "white-light" laser generated supercontinuum. The system can be configured to record spectral transients in two operating modes: 350 - 900 nm, and 800 - 1600 nm. Sample holders for cuvettes and thin films are available.

Nanosecond Transient Absorption Spectroscopy

A broadband transient absorption spectrometer is available that can be configured to measure long-lived electronic and chemical species with sub-ns time resolution in a time window of 0 - 50 microseconds (EOS, Ultrafast Systems). In this configuration, spectral transients can be recorded in one of two operating modes: 370 - 900 nm or 800 - 1700 nm. Sample holders for cuvettes and thin films are available.

Time Correlated Single Photon Counting Spectroscopy

A commercial lifetime spectrometer (Picoquant FT200) is available to measure ultrafast emission processes in the visible and NIR range (400 - 1450 nm) with a time resolution of ~ 25 ps in a time window of 0 - 100 microseconds. It uses an ultrafast oscillator (Tsunami Spectra Physics) in combination with a frequency doubler/pulse picker to provide excitation in the 350nm-490nm spectral range at variable repetition rates from 8MHz down to 10 kHz. This allows users to measure both short (10ps) and slow (tens of microseconds) excitonic lifetimes. Sample holders for cuvettes, and thin films are available, including a low temperature liquid N2 cryostat. Data analysis software (Fluofit Picoquant) is also available.

Ultrafast and Nonlinear Optical Microscopy

Contact: Mircea Cotlet

Confocal Photoluminescence/Fluorescence and Electroluminescence Microscopy

This is a CFN manufactured confocal scanning microscope based on a Olympus IX81 inverted microscope with dual color pulsed laser excitation (440nm and 532nmt), Silicon-based photon counting detectors (400-1100nm range) for time-resolved two-color and polarization photoluminescence imaging, and an Acton SP2750-Pixis100 spectrograph-CCD system for micro-PL spectroscopy (400-1100nm range). The microscope has single nanostructure sensitivity iand it performs single photon source characterization for quantum materials. The system is equipped with a liquid He cryostat (4.5K) and can be coupled with a Nanosurf AFM for correlative confocal/AFM imaging.

Confocal Hyperspectral Dark Field/ Bright Field/Fluorescence Imaging Microscopy with Single Nanoparticle Sensitivity

This is a commercial NT&C NanoMicoSpec Nikon Eclipe T2 inverted microscope equipped with a laser driven white light ultrastable It performs confocal hyperspectral dark field scattering, fluorescence iand absorption. Single nanoparticle sensitivity is available in both scattering and fluorescence modes.

Confocal Hyperspectral High-Speed Laser Scanning Fluorescence Microscopy with Multiphoton Capability

A commercial Leica TCS SP5 laser-scanning confocal/multiphoton fluorescence microscope is available for users wishing to perform fast scanning/imaging (video rate) of fluorescent samples. It includes several continuous wave lasers (Ar-ion 457nm, 488nm, 514nm, He Ne 543nm and 632nm) for hyperspectral confocal imaging and a broad band ultrafast Ti:Sapphire oscillator (MaiTai Spectra Physics) for multiphoton and second harmonic imaging microscopy

Scanning Photocurrent Microscopy

This is a CFN manufactured instrument based on an inverted Olympus IX81 microscope equipped with 488nm, 561nm and 632nm lasers, a 50x long working distance objective lens, and with reflection image capability. It offers users with the ability to record photocurrent maps with 400nm resolution with samples usually integrated in a FET format, measure carrier diffusion lengths. FET samples can be built in the CFN clean room facility, including wire bonding.