Perspective: THz-driven nuclear dynamics from solids to molecules

Hamm, Peter; Meuwly, Markus; Johnson, S. L.; Beaud, P.; Staub, U.

doi:10.1063/1.4992050

Cited by 24 publications

(10 citation statements)

References 149 publications

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“…As a result, THz radiation can be successfully applied for medical diagnostics, industrial quality control, food inspection, homeland security, and others [1][2][3][4] . Moreover, THz waves are of great interest for purely scientific applications, since they can directly probe vibrational and rotational transitions, dynamics of free carriers and phonon resonances [5][6][7] .…”

mentioning

confidence: 99%

Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments

et al. 2020

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Extreme nonlinear interactions of THz electromagnetic fields with matter are the next frontier in nonlinear optics. However, reaching this frontier in free space is limited by the existing lack of appropriate powerful THz sources. Here, we experimentally demonstrate that two-color filamentation of femtosecond mid-infrared laser pulses at 3.9 μm allows one to generate ultrashort sub-cycle THz pulses with sub-milijoule energy and THz conversion efficiency of 2.36%, resulting in THz field amplitudes above 100 MV cm −1. Our numerical simulations predict that the observed THz yield can be significantly upscaled by further optimizing the experimental setup. Finally, in order to demonstrate the strength of our THz source, we show that the generated THz pulses are powerful enough to induce nonlinear cross-phase modulation in electro-optic crystals. Our work paves the way toward free space extreme nonlinear THz optics using affordable table-top laser systems.

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confidence: 99%

Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments

et al. 2020

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“…The direct observation of multiple vibrational modes across a broad spectral window (typically over 1500 cm −1 ) is a notable advantage of FSRS over other ultrafast spectroscopic techniques. To observe even lower frequency modes (e.g., <300 cm −1 ) for protein samples in solution, which may report slower protein motions or collective (likely intermolecular in nature) vibrational motions that are coupled to the ultrafast processes such as ESPT reaction, other advanced spectroscopic techniques such as the femtosecond time-domain Raman spectroscopy [ 25 ] and terahertz absorption spectroscopy [ 49 , 50 ] can be implemented.…”

Section: Resultsmentioning

confidence: 99%

Excited State Structural Evolution of a GFP Single-Site Mutant Tracked by Tunable Femtosecond-Stimulated Raman Spectroscopy

et al. 2018

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Tracking vibrational motions during a photochemical or photophysical process has gained momentum, due to its sensitivity to the progression of reaction and change of environment. In this work, we implemented an advanced ultrafast vibrational technique, femtosecond-stimulated Raman spectroscopy (FSRS), to monitor the excited state structural evolution of an engineered green fluorescent protein (GFP) single-site mutant S205V. This mutation alters the original excited state proton transfer (ESPT) chain. By strategically tuning the Raman pump to different wavelengths (i.e., 801, 539, and 504 nm) to achieve pre-resonance with transient excited state electronic bands, the characteristic Raman modes of the excited protonated (A*) chromophore species and intermediate deprotonated (I*) species can be selectively monitored. The inhomogeneous distribution/population of A* species go through ESPT with a similar ~300 ps time constant, confirming that bridging a water molecule to protein residue T203 in the ESPT chain is the rate-limiting step. Some A* species undergo vibrational cooling through high-frequency motions on the ~190 ps time scale. At early times, a portion of the largely protonated A* species could also undergo vibrational cooling or return to the ground state with a ~80 ps time constant. On the photoproduct side, a ~1330 cm−1 delocalized motion is observed, with dispersive line shapes in both the Stokes and anti-Stokes FSRS with a pre-resonance Raman pump, which indicates strong vibronic coupling, as the mode could facilitate the I* species to reach a relatively stable state (e.g., the main fluorescent state) after conversion from A*. Our findings disentangle the contributions of various vibrational motions active during the ESPT reaction, and offer new structural dynamics insights into the fluorescence mechanisms of engineered GFPs and other analogous autofluorescent proteins.

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“…In comparison with other schemes for generating intense THz pulses, the approach demonstrated here stands out in terms of the peak power (∼TW) and spectral brightness (brightness temperature greater than 10 21 K), as well as its broadband spectral tunability. Such a THz source may open up new avenues for nonlinear THz field-matter interactions [66], compact particle accelerators [67], and multidimensional pump-probe experiments [68] that are operated at a low repetition rate. Moreover, the unprecedentedly high peak power could allow access to a fully new paradigm of relativistic optics [69] in the THz regime, where there should be an abundance of new physics, as evidenced by the recently emerging ultra-intense laser interactions at midinfrared wavelengths [70][71][72].…”

Section: Discussionmentioning

confidence: 99%

Towards Terawatt-Scale Spectrally Tunable Terahertz Pulses via Relativistic Laser-Foil Interactions

et al. 2020

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An ever-increasing number of strong-field applications, such as ultrafast coherent control over matter and light, require driver light pulses that are both high power and spectrally tunable. The realization of such a source in the terahertz (THz) band has long been a formidable challenge. Here, we demonstrate, via experiment and theory, efficient production of terawatt (TW)-level THz pulses from high-intensity picosecond laser irradiation on a metal foil. It is shown that the THz spectrum can be manipulated effectively by tuning the laser pulse duration or target size. A general analytical framework for THz generation is developed, involving both the high-current electron emission and a time-varying electron sheath at the target rear, and the spectral tunability is found to stem from the change of the dominant THz generation mechanism. In addition to being an ultrabright source (brightness temperature of about 10 21 K) for extreme THz science, the THz radiation presented here also enables a unique in situ laser-plasma diagnostic. Employing the THz radiation to quantify the escaping electrons and the transient sheath shows good agreement with experimental measurements.

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Perspective: THz-driven nuclear dynamics from solids to molecules

Cited by 24 publications

References 149 publications

Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments

Observation of extremely efficient terahertz generation from mid-infrared two-color laser filaments

Excited State Structural Evolution of a GFP Single-Site Mutant Tracked by Tunable Femtosecond-Stimulated Raman Spectroscopy

Towards Terawatt-Scale Spectrally Tunable Terahertz Pulses via Relativistic Laser-Foil Interactions

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