Breaking the nanosecond barrier in FTIR time-resolved spectroscopy

The state of the art in broad spectral bandwidth infrared time-resolved spectroscopy (IRTRS) is reviewed, with particular regard to time resolution in the nanosecond and sub-nanosecond regime. While step-scan Fourier transform infrared (S2FTIR) has been successful in pushing the time resolution of IRTRS to sub-microsecond limits, and is, in principle, applicable for monitoring time-dependent phenomena on any time scale, a practical limit for S2FTIR is currently about 1 ns, due to the limitations of parts of the instrument other than the interferometer itself. For the particular case of IRTRS of transient photo-excited states illustrated here and other photoexcitation studies, it is proposed that the most effective way to breach the nanosecond barrier and to push the time resolution limit of IRTRS to 10 ps, or even lower, while still maintaining the spectral bandwidth and resolution and the multiplex and throughput advantages of interferometry, is to turn to constant velocity, continuous-scan (CS) FTIR, in the pump-probe asynchronous sampling mode. In the method described, the pump is provided by the picosecond UV pulse of an electron storage ring-powered free electron laser and the infrared probe is the picosecond 'white light' synchrotron pulse from the same storage ring. The design specifications of this system are 10 ps time resolution with 3 cm 1 spectral resolution. © 1999 Elsevier Science B.V. All rights reserved.

Duke Scholars

Author Richard A. Palmer Chemistry