By Center for Functional Nanomaterials Brookhaven
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.
