Breaking Barriers in Ultrafast Spectroscopy and Imaging Using 100 kHz Amplified Yb-Laser Systems

Abstract

Conspectus Ultrafast spectroscopy and imaging have become tools utilized by a broad range of scientists involved in materials, energy, biological, and chemical sciences. Commercialization of ultrafast spectrometers including transient absorption spectrometers, vibrational sum frequency generation spectrometers, and even multidimensional spectrometers have put these advanced spectroscopy measurements into the hands of practitioners originally outside the field of ultrafast spectroscopy. There is now a technology shift occurring in ultrafast spectroscopy, made possible by new Yb-based lasers, that is opening exciting new experiments in the chemical and physical sciences. Amplified Yb-based lasers are not only more compact and efficient than their predecessors but also, most importantly, operate at many times the repetition rate with improved noise characteristics in comparison to the previous generation of Ti:sapphire amplifier technologies. Taken together, these attributes are enabling new experiments, generating improvements to long-standing techniques, and affording the transformation of spectroscopies to microscopies. This Account aims to show that the shift to 100 kHz lasers is a transformative step in nonlinear spectroscopy and imaging, much like the dramatic expansion that occurred with the commercialization of Ti:sapphire laser systems in the 1990s. The impact of this technology will be felt across a great swath of scientific communities. We first describe the technology landscape of amplified Yb-based laser systems used in conjunction with 100 kHz spectrometers operating with shot-to-shot pulse shaping and detection. We also identify the range of different parametric conversion and supercontinuum techniques which now provide a path to making pulses of light optimal for ultrafast spectroscopy. Second, we describe specific instances from our laboratories of how the amplified Yb-based light sources and spectrometers are transformative. For multiple probe time-resolved infrared and transient 2D IR spectroscopy, the gain in temporal span and signal-to-noise enables dynamical spectroscopy measurements from femtoseconds to seconds. These gains widen the applicability of time-resolved infrared techniques across a range of topics in photochemistry, photocatalysis, and photobiology as well as lower the technical barriers to implementation in a laboratory. For 2D visible spectroscopy and microscopy with white light, as well as 2D IR imaging, the high repetition rates of these new Yb-based light sources allow one to spatially map 2D spectra while maintaining high signal-to-noise in the data. To illustrate the gains, we provide examples of imaging applications in the study of photovoltaic materials and spectroelectrochemistry.

Biomolecular infrared spectroscopy: making time for dynamics

“…Signicant advances have already been described above including the advent of high pulse repetition rate Yb-based lasers and pulse shaping. 131 While associated developments in hardware continue to bring improvements in available technology. 132 This is complemented by improvements in data acquisition methods and data pre- 133,134 and post-processing 135 to limit the effects of baseline uctuations as well as techniques to improve background subtraction 136 and to normalise data 104 to enable accurate comparisons between different samples.…”

Laser induced temperature-jump time resolved IR spectroscopy of zeolites

“…The goal of the work in this paper is the development of methods of IR laser spectroscopy that can initiate and probe chemical change in zeolites across timescales of nanoseconds to seconds. Pulsed-laser infrared (IR) absorption spectroscopy allows vibrational spectra to be recorded with a time resolution as small as femtoseconds, 4,5 allowing the study of dynamical processes such as bond breaking, structural rearrangements and molecular diffusion. 6–9 Dynamical processes are initiated by pulsed-laser excitation and monitored with synchronised, time-resolved spectroscopic probing of the resulting molecular changes.…”

High-flux, ultraviolet-to-visible-tunable, ultrafast light source based on gas-filled capillary fibre system

“…This mechanism has recently been extended to largecore capillary bre [27][28][29][30] , leading to the vacuum to deep UV (110 nm to 400 nm) dispersive-wave generation with unprecedented high pulse energies. Besides ultrashort pulse width and high pulse energy, high pulse repetition rate and high photon ux are also two highly-demanded laser parameters, especially for advanced applications of such laser systems in ultrafast spectroscopy and pump-probe measurements [3][4][5][6][31][32][33] . In practice, high pulse repetition rate and high photon ux can directly lead to shorter measurement time as well as improved detection sensitivity, both of which are crucial for these cutting-edge applications 8, [31][32][33] .…”