Noisy Optical Pulses Enhance the Temporal Resolution of Pump-Probe Spectroscopy

Meyer, Kristina; Ott, Christian; Raith, Philipp; Kaldun, Andreas; Jiang, Yuhai; Senftleben, Arne; Курка, М.; Moshammer, R.; Ullrich, J.; Pfeifer, Thomas

doi:10.1103/physrevlett.108.098302

Cited by 31 publications

(15 citation statements)

References 24 publications

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“…Other things being equal, the time resolution is determined by the signal expected from an infinitely short pulse, convolved with the actual probe envelope. In agreement with previous work on partially coherent optical pulses 28 , our results suggest that the X-ray pulse contains spikes that are sufficiently narrow to allow extraction of information beyond the nominal pulse envelope. The time resolution also depends on several other experimental parameters, including the timing uncertainty, the magnitude and uniformity of the time interval between snapshots 29 , their signal-to-noise ratio, and the characteristics of the signal itself.…”

Section: Letter Researchsupporting

confidence: 91%

Dynamics from noisy data with extreme timing uncertainty

Fung

Hanna

Vendrell

et al. 2016

Nature

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Imperfect knowledge of the times at which 'snapshots' of a system are recorded degrades our ability to recover dynamical information, and can scramble the sequence of events. In X-ray free-electron lasers, for example, the uncertainty-the so-called timing jitterbetween the arrival of an optical trigger ('pump') pulse and a probing X-ray pulse can exceed the length of the X-ray pulse by up to two orders of magnitude 1 , marring the otherwise precise time-resolution capabilities of this class of instruments. The widespread notion that little dynamical information is available on timescales shorter than the timing uncertainty has led to various hardware schemes to reduce timing uncertainty [2][3][4] . These schemes are expensive, tend to be specific to one experimental approach and cannot be used when the record was created under ill-defined or uncontrolled conditions such as during geological events. Here we present a data-analytical approach, based on singular-value decomposition and nonlinear Laplacian spectral analysis [5][6][7] , that can recover the history and dynamics of a system from a dense collection of noisy snapshots spanning a sufficiently large multiple of the timing uncertainty. The power of the algorithm is demonstrated by extracting the underlying dynamics on the few-femtosecond timescale from noisy experimental X-ray free-electron laser data recorded with 300-femtosecond timing uncertainty 1 . Using a noisy dataset from a pump-probe experiment on the Coulomb explosion of nitrogen molecules, our analysis reveals vibrational wave-packets consisting of components with periods as short as 15 femtoseconds, as well as more rapid changes, which have yet to be fully explored. Our approach can potentially be applied whenever dynamical or historical information is tainted by timing uncertainty.The fundamental premise of our approach is simple. A series of snapshots concatenated in the order of their inaccurate time stamps will contain some time-evolutionary information ('a weak arrow of time'), provided that the concatenation window spans a period comparable with, or longer than, the timing uncertainty associated with each individual snapshot. This realization leads one to consider a series of c-fold concatenated snapshots, formed by moving a c-frame-wide window over the raw dataset ordered according to the inaccurate time stamps. The dynamical history can then be extracted from the series of concatenated snapshots using techniques developed to extract signal from noise, such as singular-value decomposition (SVD) 8 . SVD determines a series of statistically significant modes, each consisting of a characteristic pattern (topogram) and its time evolution (chronogram). A topogram can be a characteristic image or spectrum, with the corresponding chronogram showing its change with time. For each mode, a singular value specifies the power contained in that mode 8 .Consider snapshots, such as images or spectra, that can be represented as vectors by using the pixel values of each snapshot as the components of a ve...

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Section: Letter Researchsupporting

confidence: 91%

Dynamics from noisy data with extreme timing uncertainty

Fung

Hanna

Vendrell

et al. 2016

Nature

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“…This is similar to observations that the temporal resolution of a nonlinear optical process with chaotic light is determined by the temporal coherence time, rather than the pulse duration, if the temporal, longitudinal, coherence time is smaller than typical relaxation processes or typical time constant in the system [42][43][44]. Increasing the pulse duration of the SASE pulses, the spectral coherence can be further decreased, resulting in a narrowing of the emission lines and an increased spectral resolution.…”

Section: High Resolution By Covariance Analysissupporting

confidence: 83%

Stimulated resonant x-ray Raman scattering with incoherent radiation

Weninger

Rohringer

2013

Phys. Rev. A

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We present a theoretical study on stimulated electronic Raman scattering in neon by resonant excitation with an x-ray free electron laser (XFEL). This study is in support of the recent experimental demonstration [C. Weninger et al., Phys. Rev. Lett. (to be published)] of stimulated x-ray Raman scattering. Focusing the broadband XFEL pulses into a cell of neon gas at atmospheric pressure a strong inelastic x-ray scattering signal in the forward direction was observed, as the x-ray energy was varied across the region of core-excited Rydberg states and the K edge. The broadband and intrinsically incoherent x-ray pulses from the XFEL lead to a rich, structured line shape of the scattered radiation. We present a generalized Maxwell-Liouville-von Neumann approach to self-consistently solve for the amplification of the scattered radiation along with the time evolution of the density matrix of the atomic and residual ionic system. An in-depth analysis of the evolution of the emission spectra as a function of the Raman gain is presented. Furthermore, we propose the use of statistical methods to obtain high-resolution scattering data beyond the lifetime broadening despite pumping with incoherent x-ray pulses.

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“…One exception is coherent anti-Stokes Raman scattering spectroscopy (I (2) CARS), where the noisy-light version has proven to be a very useful tool that is still being used to investigate a variety of systems [87,[102][103][104][105][106][107][108][109][110][111][112][113][114][115][116]. Noisy sources have found occasional uses and advantages in other spectral regimes as well [117][118][119][120][121].…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis

Turner

Howey²,

Sutor³

et al. 2012

J. Phys. Chem. A

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Electronic energy transfer in photosynthesis occurs over a range of time scales and under a variety of intermolecular coupling conditions. Recent work has shown that electronic coupling between chromophores can lead to coherent oscillations in two-dimensional electronic spectroscopy measurements of pigment-protein complexes measured with femtosecond laser pulses. A persistent issue in the field is to reconcile the results of measurements performed using femtosecond laser pulses with physiological illumination conditions. Noisy-light spectroscopy can begin to address this question. In this work we present the theoretical analysis of incoherent two-dimensional electronic spectroscopy, I(4) 2D ES. Simulations reveal diagonal peaks, cross peaks, and coherent oscillations similar to those observed in femtosecond two-dimensional electronic spectroscopy experiments. The results also expose fundamental differences between the femtosecond-pulse and noisy-light techniques; the differences lead to new challenges and new opportunities.

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Noisy Optical Pulses Enhance the Temporal Resolution of Pump-Probe Spectroscopy

Cited by 31 publications

References 24 publications

Dynamics from noisy data with extreme timing uncertainty

Dynamics from noisy data with extreme timing uncertainty

Stimulated resonant x-ray Raman scattering with incoherent radiation

Two-Dimensional Electronic Spectroscopy Using Incoherent Light: Theoretical Analysis

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