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Advanced Optical Spectroscopy and Microscopy

optics

The Advanced Optical Spectroscopy & Microscopy Facility combines a broad range of optical instruments suitable for studies of optical properties of hard, soft or biological materials using ultrafast and nonlinear spectroscopy, and single-molecule optical and confocal methods.

Capabilities

  • Time-Resolved Confocal Photoluminescence Imaging in UV-VIS (400-1100nm)
  • Time-resolved Confocal Photoluminescence Imaging in NIR (800-1750nm)
  • Time-Resolved Photoluminescence Spectroscopy in UV-VIS (400-859nm) and NIR (950-1450nm)
  • Steady State Photoluminescence Spectroscopy in UV-VIS (400-1100nm) and NIR (800-1750nm)
  • Multicolor High-Speed Laser Scanning Confocal Fluorescence Imaging and Hyperspectral Imaging
  • Non-Linear Imaging: Second Harmonic Generation and Two-Photon Photoluminescence.
  • 2D Wide Field Imaging, Polarization, DIC, Dark-Field and TIRFM Imaging.
  • Transient absorption and reflectivity spectroscopy: broadband femtosecond and nanosecond probes covering UV, VIS and NIR; two-color low temperature pump-probe spectroscopy
  • Z-Scan measurements of optical nonlinearities: open and closed aperture with tunable excitation wavelength
  • Advanced data analysis methods, including single decay and global fits using a variety of kinetic models

Ultrafast and Nonlinear Spectroscopy

Contact: Matthew Sfeir

Our facility houses a state-of-the-art high power kilohertz femtosecond regenerative amplifier combined with an optical parametric amplifier that allows generation of sub 100 femtosecond pulses in the ultraviolet, visible, and infrared regions of the spectrum. This system is coupled to a series of user-friendly time-resolved and nonlinear optical techniques, providing Users with a broad suit of tools for characterizing the photophysical properties of their materials, including:

Femtosecond Transient Absorption Spectroscopy

The CFN houses a broadband transient absorption spectrometer with approximately 100 fs time resolution in a time window of 0 - 3 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 one of three operating modes: 350 - 700 nm, 450 - 820 nm, or 800 - 1600 nm.  Sample holders for cuvettes and thin films are available.

Nanosecond Transient Absorption Spectroscopy

In addition, the broadband transient absorption spectrometer can be configured to measure long-lived electronic and chemical species with sub-ns time resolution in a time window of 0 - 50 microseconds. 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.  This is an optically gated technique using a femtosecond excitation pulse and a longer (~ 500 ps) white-light laser probe pulse.

Fluorescence Upconversion Spectroscopy

This spectrometer is able to measure ultrafast emission processes in the visible and NIR (400 - 1600 nm) with a time resolution of ~ 100 fs in a time window of 0 - 3 ns.  In the upconversion method, the emitted photons are mixed with an optical gate pulse in a nonlinear crystal optimized for sum frequency generation.  We detect the intensity of the higher energy upconverted photons as a function of time delay between the excitation pulse and the gate pulse to map out the kinetics. Alternatively, spectral emission transients can be recorded at a fixed delay time.  For longer kinetic processes, the spectrometer can also be operated in time-correlated single photon counting mode (TCSPC) in which the emitted photons are directly detected.  The use of fast electronics allows for a time resolution of 100 ps over a range of 0 – 1 ms.

Z-Scan Measurements for Determining Optical Nonlinearities

We have implemented this technique for measuring multi-photon absorption coefficients and nonlinear refractive indices of novel photonic materials.    In this experiment, a thin solid or liquid sample is translated through the focus of high pulse energy NIR light (700 – 1200 nm).  The normalized transmission is detected as a function of position along the light focus and used to derive the nonlinear optical coefficients.

Time-Resolved Confocal Imaging And Nonlinear Imaging Microscopies

Contact: Mircea Cotlet

Time-Resolved Confocal Photoluminescence Microscopy for UV-VIS (400-1100nm)

  • INSTRUMENT: Olympus IX81 inverted microscope with raster scanning stage (80x80 microns), various objective lenses (oil 100x, 1.4NA, oil 60x, 1.45 NA, water 60x, 1.2NA, air 100x, 0.95NA and 60x, 0.9NA).
  • DETECTION: 4 Si-based single photon counting detectors (400-1100nm range) for time-resolved two-color and polarization PL imaging, and an Acton SP2300-Pixis100 spectrograph/CCD system for micro-PL spectroscopy (400-1100nm range). Single nanocrystal sensitivity possible
  • EXCITATION: broadband femtosecond laser system with colors available in the 375-490nm and 570-650nm ranges, with variable repletion rate (80MHz-1 kHz).
  • DATA ACQUSITION/ANALYSIS: User friendly Picoquant Symphotime 5.32 software for FLIM data acquisition/analysis including MLE fitting, PL blinking analysis, FRET and FCS, WinSpec for micro-PL spectra.
  • ACCESSORIES: Microscope can be combined/adapted with AFM (NanoSurf), electrical probing and electrochemistry measurements (electrochemical cell).

Time-Resolved Confocal Photoluminescence Microscopy for NIR (800-1750nm)

  • INSTRUMENT: Olympus IX71 inverted microscope with raster scanning stage (80x80 microns), various objective lenses (oil 100x, 1.4NA, oil 60x, 1.45 NA, water 60x, 1.2NA, air 100x, 0.95NA and 60x, 0.9NA).
  • DETECTOR: InGaAs (850-1750nm) and NIR enhanced Si-based (400-1100nm) single photon counting detectors for FLIM, IHR320 Horiba Spectrograph and InGaAs Symphony II CCD detector for micro PL spectroscopy in NIR range. Single nanocrystal sensitivity.
  • EXCITATION: broad-band femtosecond laser system with colors available in the range 375-490nm, 570-650nm and 710-980nm, with variable repetition rate (80MHz-1 kHz).
  • DATA ACQUSITION/ANALYSIS: User friendly Picoquant Symphotime 5.32 software for FLIM data acquisition and analysis, Horiba Fluorescence software for micro-PL spectroscopy in NIR range.

Time-resolved Photoluminescence Spectroscopy in UV-VIS-NIR (400-850nm, 950-1450nm)

  • DETECTORS: Hamamatsu MCP-PMT detector for UV-VIS (45 ps response, 400-850nm) and Hamamatsu InGaAs PMT (400-ps response, 950-1450nm).
  • EXCITATION: broadband femtosecond laser system with colors available in the range 370-480nm, 560-650nm, with variable repletion rate (8MHz-1 kHz).
  • DATA ANALYSIS: User friendly Picoquant FluoFit data analysis software including global analysis and various fitting models (Multiexponential, stretched, Gauss, Lorentz).

Nonlinear Imaging Microscopy includes SHG, 2-Photon Photoluminescence, Up-conversion Imaging

  • INSTRUMENT: Inverted Olympus IX-71 microscope with 2D imaging by raster-scanning (80x80µm area). SHG operates in backscattering. Available objective lenses include oil (100x, 1.4NA, 60x, 1.45 NA), water (60x, 1.2NA) and air (100x, 0.95NA and 60x, 0.9NA)
  • DETECTORS: Single photon counting detection (APD SPQM14, Excelitas) for imaging, Ocean Optics Q65000 spectrometer for micro spectroscopy.
  • EXCITATION: broadband MaiTai femtosecond laser (710-980nm).

Steady-State Photoluminescence Spectroscopy for UV-VIS-NIR (400-1750nm)

  • INSTRUMENT: Horiba Nanolog Hybrid Fluorimeter for UV-VIS-NIR for conventional PL spectroscopy in solution (cuvette) or thin film including polarized PL.
  • EXCITATION: 75W Xe lamp with Gemini Horiba monochromator
  • DETECTORS: IH320 Horiba spectrograph with InGaAS CCD Symphony II for NIR PL spectra (800-1750nm) and Ocean Optics 65000FL spectrograph/CCD for UV-VIS PL spectra (400-1100nm).

Leica SP5 TCS high speed laser scanning confocal imaging/ hyperspectral imaging microscope

  • INSTRUMENT: Commercial inverted Leica SP5 TCS laser-scanning confocal fluorescence microscope for fast scanning/imaging (video rate) includes several objective lenses (63x 1.4 NA oil, 63x 1.2 NA water, 10x 0.5NA oil and 10x 0.2 NA air)
  • DETECTORS: 3-PMT channels (400-800nm range) for simultaneous imaging of three different colors, transmission & reflection imaging, DIC, polarization imaging.
  • EXCITATION: CW lasers, Ar-ion 457nm, 488nm, 514nm, He Ne 543nm and 632nm.
  • MODES: Confocal PL imaging, FRET, FRAP, FCS, HyperSpectral Imaging, micro PL spectroscopy.
  • DATA ACQUISITION/ANALYSIS: Commercial user friendly LAF Software for hands free operation includes 3D reconstruction.

2D Imaging by Dark- Field, Wide-Field, DIC and TIRFM (EM-CCD based)

  • INSTRUMENT: Olympus IX81 Imaging microscope with through objective TIRF (60x 1.45 NA oil lens) for 2D imaging with millisecond time exposure and diffraction limited spatial resolution. Additional objectives are air 40x and 20x.
  • DETECTOR: EM-CCD Hamamatsu camera with optional dual optics for FRET and co-localization studies. TIRF dichroic is optimized for 530/50nm (FITC), 600/40nm (TRITC) and 670/30nm (Cy5). Dual View optics contains a 565nm dichroic with a 530/30nm (green channel) and a 590/40nm (red channel). Single nanocrystals sensitivity.
  • DATA ACQUISITION/ANALYSIS: Slidebook including 2D single particle tracking.
  • MODES: Wide field imaging, dark field imaging (20x, 40x), DIC and TIRFM, dual-TIRFM.