Siqi Li

All Publications

• Attosecond coherent electron motion in Auger-Meitner decay. Science (New York, N.Y.) Li, S., Driver, T., Rosenberger, P., Champenois, E. G., Duris, J., Al-Haddad, A., Averbukh, V., Barnard, J. C., Berrah, N., Bostedt, C., Bucksbaum, P. H., Coffee, R. N., DiMauro, L. F., Fang, L., Garratt, D., Gatton, A., Guo, Z., Hartmann, G., Haxton, D., Helml, W., Huang, Z., LaForge, A. C., Kamalov, A., Knurr, J., Lin, M., Lutman, A. A., MacArthur, J. P., Marangos, J. P., Nantel, M., Natan, A., Obaid, R., O'Neal, J. T., Shivaram, N. H., Schori, A., Walter, P., Wang, A. L., Wolf, T. J., Zhang, Z., Kling, M. F., Marinelli, A., Cryan, J. P. 1800: eabj2096

  Abstract

  [Figure: see text].

  View details for DOI 10.1126/science.abj2096

  View details for PubMedID 34990213

• Time-resolved pump-probe spectroscopy with spectral domain ghost imaging. Faraday discussions Li, S., Driver, T., Alexander, O., Cooper, B., Garratt, D., Marinelli, A., Cryan, J. P., Marangos, J. P. 2021

  Abstract

  An atomic-level picture of molecular and bulk processes, such as chemical bonding and charge transfer, necessitates an understanding of the dynamical evolution of these systems. On the ultrafast timescales associated with nuclear and electronic motion, the temporal behaviour of a system is often interrogated in a 'pump-probe' scheme. Here, an initial 'pump' pulse triggers dynamics through photoexcitation, and after a carefully controlled delay a 'probe' pulse initiates projection of the instantaneous state of the evolving system onto an informative measurable quantity, such as electron binding energy. In this paper, we apply spectral ghost imaging to a pump-probe time-resolved experiment at an X-ray free-electron laser (XFEL) facility, where the observable is spectral absorption in the X-ray regime. By exploiting the correlation present in the shot-to-shot fluctuations in the incoming X-ray pulses and measured electron kinetic energies, we show that spectral ghost imaging can be applied to time-resolved pump-probe measurements. In the experiment presented, interpretation of the measurement is simplified because spectral ghost imaging separates the overlapping contributions to the photoelectron spectrum from the pump and probe pulse.

  View details for DOI 10.1039/d0fd00122h

  View details for PubMedID 33625412

• Electronic Population Transfer via Impulsive Stimulated X-Ray Raman Scattering with Attosecond Soft-X-Ray Pulses. Physical review letters O'Neal, J. T., Champenois, E. G., Oberli, S., Obaid, R., Al-Haddad, A., Barnard, J., Berrah, N., Coffee, R., Duris, J., Galinis, G., Garratt, D., Glownia, J. M., Haxton, D., Ho, P., Li, S., Li, X., MacArthur, J., Marangos, J. P., Natan, A., Shivaram, N., Slaughter, D. S., Walter, P., Wandel, S., Young, L., Bostedt, C., Bucksbaum, P. H., Picón, A., Marinelli, A., Cryan, J. P. 2020; 125 (7): 073203

  Abstract

  Free-electron lasers provide a source of x-ray pulses short enough and intense enough to drive nonlinearities in molecular systems. Impulsive interactions driven by these x-ray pulses provide a way to create and probe valence electron motions with high temporal and spatial resolution. Observing these electronic motions is crucial to understand the role of electronic coherence in chemical processes. A simple nonlinear technique for probing electronic motion, impulsive stimulated x-ray Raman scattering (ISXRS), involves a single impulsive interaction to produce a coherent superposition of electronic states. We demonstrate electronic population transfer via ISXRS using broad bandwidth (5.5 eV full width at half maximum) attosecond x-ray pulses produced by the Linac Coherent Light Source. The impulsive excitation is resonantly enhanced by the oxygen 1s→2π^{*} resonance of nitric oxide (NO), and excited state neutral molecules are probed with a time-delayed UV laser pulse.

  View details for DOI 10.1103/PhysRevLett.125.073203

  View details for PubMedID 32857563

• Electronic Population Transfer via Impulsive Stimulated X-Ray Raman Scattering with Attosecond Soft-X-Ray Pulses PHYSICAL REVIEW LETTERS O'Neal, J. T., Champenois, E. G., Oberli, S., Obaid, R., Al-Haddad, A., Barnard, J., Berrah, N., Coffee, R., Duris, J., Galinis, G., Garratt, D., Glownia, J. M., Haxton, D., Ho, P., Li, S., Li, X., MacArthur, J., Marangos, J. P., Natan, A., Shivaram, N., Slaughter, D. S., Walter, P., Wandel, S., Young, L., Bostedt, C., Bucksbaum, P. H., Picon, A., Marinelli, A., Cryan, J. P. 2020; 125 (7)

  View details for DOI 10.1103/PhysRevLett.125.073203

  View details for Web of Science ID 000558086800003

• Tunable isolated attosecond X-ray pulses with gigawatt peak power from a free-electron laser NATURE PHOTONICS Duris, J., Li, S., Driver, T., Champenois, E. G., MacArthur, J. P., Lutman, A. A., Zhang, Z., Rosenberger, P., Aldrich, J. W., Coffee, R., Coslovich, G., Decker, F., Glownia, J. M., Hartmann, G., Helml, W., Kamalov, A., Knurr, J., Krzywinski, J., Lin, M., Nantel, M., Natan, A., O'Neal, J., Shivaram, N., Walter, P., Wang, A., Welch, J. J., Wolf, T. A., Xu, J. Z., Kling, M. F., Bucksbaum, P. H., Zholents, A., Huang, Z., Cryan, J. P., Marinelli, A., Marangos, J. P. 2020; 14 (1): 30-+

  View details for DOI 10.1038/s41566-019-0549-5

  View details for Web of Science ID 000504727600007

• Attosecond transient absorption spooktroscopy: a ghost imaging approach to ultrafast absorption spectroscopy. Physical chemistry chemical physics : PCCP Driver, T., Li, S., Champenois, E. G., Duris, J., Ratner, D., Lane, T. J., Rosenberger, P., Al-Haddad, A., Averbukh, V., Barnard, T., Berrah, N., Bostedt, C., Bucksbaum, P. H., Coffee, R., DiMauro, L. F., Fang, L., Garratt, D., Gatton, A., Guo, Z., Hartmann, G., Haxton, D., Helml, W., Huang, Z., LaForge, A., Kamalov, A., Kling, M. F., Knurr, J., Lin, M., Lutman, A. A., MacArthur, J. P., Marangos, J. P., Nantel, M., Natan, A., Obaid, R., O'Neal, J. T., Shivaram, N. H., Schori, A., Walter, P., Li Wang, A., Wolf, T. J., Marinelli, A., Cryan, J. P. 2019

  Abstract

  The recent demonstration of isolated attosecond pulses from an X-ray free-electron laser (XFEL) opens the possibility for probing ultrafast electron dynamics at X-ray wavelengths. An established experimental method for probing ultrafast dynamics is X-ray transient absorption spectroscopy, where the X-ray absorption spectrum is measured by scanning the central photon energy and recording the resultant photoproducts. The spectral bandwidth inherent to attosecond pulses is wide compared to the resonant features typically probed, which generally precludes the application of this technique in the attosecond regime. In this paper we propose and demonstrate a new technique to conduct transient absorption spectroscopy with broad bandwidth attosecond pulses with the aid of ghost imaging, recovering sub-bandwidth resolution in photoproduct-based absorption measurements.

  View details for DOI 10.1039/c9cp03951a

  View details for PubMedID 31793561

• Development of ultrafast capabilities for X-ray free-electron lasers at the linac coherent light source PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES Coffee, R. N., Cryan, J. P., Duris, J., Helml, W., Li, S., Marinelli, A. 2019; 377 (2145)

  View details for DOI 10.1098/rsta.2018.0386

  View details for Web of Science ID 000465499800015

• Development of ultrafast capabilities for X-ray free-electron lasers at the linac coherent light source. Philosophical transactions. Series A, Mathematical, physical, and engineering sciences Coffee, R. N., Cryan, J. P., Duris, J., Helml, W., Li, S., Marinelli, A. 2019; 377 (2145): 20180386

  Abstract

  The ability to produce ultrashort, high-brightness X-ray pulses is revolutionizing the field of ultrafast X-ray spectroscopy. Free-electron laser (FEL) facilities are driving this revolution, but unique aspects of the FEL process make the required characterization and use of the pulses challenging. In this paper, we describe a number of developments in the generation of ultrashort X-ray FEL pulses, and the concomitant progress in the experimental capabilities necessary for their characterization and use at the Linac Coherent Light Source. This includes the development of sub-femtosecond hard and soft X-ray pulses, along with ultrafast characterization techniques for these pulses. We also describe improved techniques for optical cross-correlation as needed to address the persistent challenge of external optical laser synchronization with these ultrashort X-ray pulses. This article is part of the theme issue 'Measurement of ultrafast electronic and structural dynamics with X-rays'.

  View details for PubMedID 30929632

• Generation and Characterization of Attosecond Pulses from an X-ray Free-electron Laser Li, S., Rosenberger, P., Champenois, E. G., Driver, T., Bucksbaum, P. H., Coffee, R., Gatton, A., Hartmann, G., Helml, W., Huang, Z., Knurr, J., Kling, M. F., Lin, M., MacArthur, J. P., Maxwell, T. J., Nantel, M., Natan, A., Oneal, J. T., Shivaram, N. H., Walter, P., Wolf, T. A., Cryan, J. P., Marinelli, A., IEEE IEEE. 2019

  View details for Web of Science ID 000482226301273

• Characterizing isolated attosecond pulses with angular streaking OPTICS EXPRESS Li, S., Guo, Z., Coffee, R. N., Hegazy, K., Huang, Z., Natan, A., Osipov, T., Ray, D., Marinelli, A., Cryan, J. P. 2018; 26 (4): 4531–47

  Abstract

  We present a reconstruction algorithm for isolated attosecond pulses, which exploits the phase dependent energy modulation of a photoelectron ionized in the presence of a strong laser field. The energy modulation due to a circularly polarized laser field is manifest strongly in the angle-resolved photoelectron momentum distribution, allowing for complete reconstruction of the temporal and spectral profile of an attosecond burst. We show that this type of reconstruction algorithm is robust against counting noise and suitable for single-shot experiments. This algorithm holds potential for a variety of applications for attosecond pulse sources.

  View details for DOI 10.1364/OE.26.004531

  View details for Web of Science ID 000426268500073

  View details for PubMedID 29475303