A 100 kHz pulse shaping 2D-IR spectrometer based on dual Yb:KGW amplifiers

Donaldson, P.M. and Greetham, G.M. and Shaw, D.J. and Parker, A.W. and Towrie, M. (2018) A 100 kHz pulse shaping 2D-IR spectrometer based on dual Yb:KGW amplifiers. Journal of Physical Chemistry A, 122 (3). 780–787. ISSN 1089-5639 (https://doi.org/10.1021/acs.jpca.7b10259)

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A high-speed, high-sensitivity and compact two-dimensional infrared (2D-IR) spectrometer based on 100 kHz Yb:KGW regenerative amplifier technology is described and demonstrated. The setup is three color, using an independent pump OPA and two separately tunable probe OPAs. The spectrometer uses 100 kHz acousto-optic pulse shaping on the pump beam for rapid 2D-IR acquisitions. The shot-to-shot stability of the laser system yields excellent signal-to-noise figures (∼10 μOD noise on 5000 laser shots). We show that the reduced bandwidth of the Yb:KGW amplifiers in comparison with conventional Ti:sapphire systems does not compromise the ability of the setup to generate high-quality 2D-IR data. Instrument responses of <300 fs are demonstrated and 2D-IR data presented for several systems of interest to physical chemists, showing spectral diffusion in NaSCN, amide I and II bands of a β sheet protein and DNA base-pair–backbone couplings. Overall, the increased data acquisition speed, intrinsic stability, and robustness of the Yb:KGW lasers are a significant step forward for 2D-IR spectroscopy.