Dual echelon femtosecond single-shot spectroscopy
We have developed a femtosecond single-shot spectroscopic technique to measure irreversible changes in condensed phase materials in real time. Crossed echelons generate a two-dimensional array of time-delayed pulses with one femtosecond probe pulse. This yields 9 ps of time-resolved data from a single laser shot, filling a gap in currently employed measurement methods. We can now monitor ultrafast irreversible dynamics in solid-state materials or other samples that cannot be flowed or replenished between laser shots, circumventing limitations of conventional pump-probe methods due to sample damage or product buildup. Despite the absence of signal-averaging in the single-shot measurement, an acceptable signal-to-noise level has been achieved via background and reference calibration procedures. Pump-induced changes in relative reflectivity as small as 0.2%−0.5% are demonstrated in semimetals, with both electronic and coherent phonon dynamics revealed by the data. The optical arrangement and the space-to-time conversion and calibration procedures necessary to achieve this level of operation are described. Sources of noise and approaches for dealing with them are discussed.
- OSTI ID:
- 22314415
- Journal Information:
- Review of Scientific Instruments, Vol. 85, Issue 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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