The Ultrafast Laser Spectroscopy facility in the Frick Chemistry Laboratory offers state-of-the-art equipment for measuring dynamics in photoactive materials on femtosecond-to-nanosecond timescales.
Ultrafast laser spectroscopy is a standard method in a number of scientific fields (physics, chemistry, molecular biology, engineering etc.) and is used both as a primary research technique, as well as an accessory characterization tool for supporting the interpretation of the experiments. This technique provides detailed information on the dynamics processes in photoactive materials (in solid and liquid phase). Such processes as excited state relaxation, both inter and intramolecular energy/electron transfer, conformational change (e.g. isomerization), and others can be studied. Details of the energetic landscape (electronic and vibrational structure) are revealed as well. Facility is capable of measuring highly sensitive materials without creation of any damage or degradation to the material.
The Ultrafast Laser Spectroscopy facility in Frick Chemistry Laboratory is open to members of any department of Princeton University. Users from outside the university are welcome as well. The manager of the facility performs the measurements, as well as offers training for long-term users.
Currently the facility allows measurements of time-resolved change of the absorption spectra (Transient Absorption) with femtosecond (10-14 s) time resolution and operates in UV-VIS-NIR spectral ranges, allowing probing all possible excited state transitions. It consists of LIBRA Ti:Sapphire amplifier (Coherent Inc.), OPerA Solo optical parametric amplifier (Coherent Inc.), and Helios transient absorption spectrometer (Ultrafast Systems). The Ti:Sapphire amplifier delivers 45fs pulses at 1kHz rate, with total power of 4.0W at 800nm wavelength. Optical parametric amplifier allows tuning of the excitation wavelength in the spectral range from 290 - 2600nm, with average power of 50mW and pulse duration 50fs. Transient absorption spectrometer allows measurements in 350 – 1600nm spectral region (probing range), and on <8ns time range. Several options for sample mounting are available in order to prevent photo-bleaching/degradation. Helios software includes dispersion compensation algorithm, anisotropy calculation and other useful tools. The measurements at different excitation intensities, wavelengths or at different temperatures of the sample can be automated. Global analysis of the data (three-dimensional array of time-resolved spectra) allows to map the exact pathways and timescales of the processes occurring in the materials of interest. This software is free and can be downloaded from the internet together with the manual and instructions.