Optical spectroscopy

The optical properties of solution and thin-film samples are characterized by both steady-state absorption(home-built) and emission (Fluorolog3, Horiba). A laser lab for time-resolved optical spectroscopy allows us to measure the photophysical dynamics of organic semiconductor systems from the femtosecond to millisecond times. There are two excitation sources. A 1 kHz (800 nm, 35 fs) laser is paired with an optical parametric amplifier to tune thee the output wavelength from 285-2000 nm (Coherent). A variable repetition rate (single shot to 100 kHz, 1030 nm, 200 fs) laser paired with a combined OPA/NOPA to tune the output wavelength from 315-2500 nm (Light Conversion/TOPAG). Transient absorption (Helios/EOS, Ultrafast Systems) with a broad spectral range (350-1600 nm) allow us to image dark excited state species, such as triplets and charge-separated states. Time resolved fluorescence is done with a Hamamatsu synchroscan and single-sweep streak cameras, and we are also installing a new gated iCCD (Stanford Computer Optics) with 200 picosecond shutter speed. Optical cryostats allow the measurement of temperature dependent optical properties, down to 4K. Our laser table is housed in a custom built environmental housing to maintain optimal temperature and humidity conditions. 

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