Yanwen Sun

All Publications

• A versatile pressure-cell design for studying ultrafast molecular-dynamics in supercritical fluids using coherent multi-pulse x-ray scattering. The Review of scientific instruments Muhunthan, P., Li, H., Vignat, G., Toro, E. R., Younes, K., Sun, Y., Sokaras, D., Weiss, T., Rajkovic, I., Osaka, T., Inoue, I., Song, S., Sato, T., Zhu, D., Fulton, J. L., Ihme, M. 2024; 95 (1)

  Abstract

  Supercritical fluids (SCFs) can be found in a variety of environmental and industrial processes. They exhibit an anomalous thermodynamic behavior, which originates from their fluctuating heterogeneous micro-structure. Characterizing the dynamics of these fluids at high temperature and high pressure with nanometer spatial and picosecond temporal resolution has been very challenging. The advent of hard x-ray free electron lasers has enabled the development of novel multi-pulse ultrafast x-ray scattering techniques, such as x-ray photon correlation spectroscopy (XPCS) and x-ray pump x-ray probe (XPXP). These techniques offer new opportunities for resolving the ultrafast microscopic behavior in SCFs at unprecedented spatiotemporal resolution, unraveling the dynamics of their micro-structure. However, harnessing these capabilities requires a bespoke high-pressure and high-temperature sample system that is optimized to maximize signal intensity and address instrument-specific challenges, such as drift in beamline components, x-ray scattering background, and multi-x-ray-beam overlap. We present a pressure cell compatible with a wide range of SCFs with built-in optical access for XPCS and XPXP and discuss critical aspects of the pressure cell design, with a particular focus on the design optimization for XPCS.

  View details for DOI 10.1063/5.0158497

  View details for PubMedID 38170817

• Low-loss stable storage of 1.2 & ANGS; X-ray pulses in a 14 m Bragg cavity NATURE PHOTONICS Margraf, R., Robles, R., Halavanau, A., Kryzywinski, J., Li, K., MacArthur, J., Osaka, T., Sakdinawat, A., Sato, T., Sun, Y., Tamasaku, K., Huang, Z., Marcus, G., Zhu, D. 2023

  View details for DOI 10.1038/s41566-023-01267-0

  View details for Web of Science ID 001048092600001

• A Contrast Calibration Protocol for X-ray Speckle Visibility Spectroscopy APPLIED SCIENCES-BASEL Sun, Y., Esposito, V., Hart, P., Hansson, C., Li, H., Nakahara, K., MacArthur, J., Nelson, S., Sato, T., Song, S., Sun, P., Fuoss, P., Sutton, M., Zhu, D. 2021; 11 (21)

  View details for DOI 10.3390/app112110041

  View details for Web of Science ID 000726897500001

• Generation of highly mutually coherent hard-x-ray pulse pairs with an amplitude-splitting delay line PHYSICAL REVIEW RESEARCH Li, H., Sun, Y., Vila-Comamala, J., Sato, T., Song, S., Sun, P., Seaberg, M. H., Wang, N., Hastings, J. B., Dunne, M., Fuoss, P., David, C., Sutton, M., Zhu, D. 2021; 3 (4)

  View details for DOI 10.1103/PhysRevResearch.3.043050

  View details for Web of Science ID 000708677100006

• Nonuniform Flow Dynamics Probed by Nanosecond X-Ray Speckle Visibility Spectroscopy PHYSICAL REVIEW LETTERS Sun, Y., Carini, G., Chollet, M., Decker, F., Dunne, M., Fuoss, P., Hruszkewycz, S. O., Lane, T. J., Nakahara, K., Nelson, S., Robert, A., Sato, T., Song, S., Stephenson, G., Sutton, M., Van Driel, T. B., Weninger, C., Zhu, D. 2021; 127 (5)

  View details for DOI 10.1103/PhysRevLett.127.058001

  View details for Web of Science ID 000679183300006

• Accurate contrast determination for X-ray speckle visibility spectroscopy JOURNAL OF SYNCHROTRON RADIATION Sun, Y., Montana-Lopez, J., Fuoss, P., Sutton, M., Zhu, D. 2020; 27: 999–1007

  View details for DOI 10.1107/S1600577520006773

  View details for Web of Science ID 000546241000016

• Accurate contrast determination for X-ray speckle visibility spectroscopy. Journal of synchrotron radiation Sun, Y., Montana-Lopez, J., Fuoss, P., Sutton, M., Zhu, D. 2020; 27 (Pt 4): 999-1007

  Abstract

  X-ray speckle visibility spectroscopy using X-ray free-electron lasers has long been proposed as a probe of fast dynamics in noncrystalline materials. In this paper, numerical modeling is presented to show how the data interpretation of visibility spectroscopy can be impacted by the nonidealities of real-life X-ray detectors. Using simulated detector data, this work provides a detailed analysis of the systematic errors of several contrast extraction algorithms in the context of low-count-rate X-ray speckle visibility spectroscopy and their origins are discussed. Here, it was found that the finite detector charge cloud and pixel size lead to an unavoidable `degeneracy' in photon position determination, and that the contrasts extracted using different algorithms can all be corrected by a simple linear model. The results suggest that experimental calibration of the correction coefficient at the count rate of interest is possible and essential. This allows computationally lightweight algorithms to be implemented for on-the-fly analysis.

  View details for DOI 10.1107/S1600577520006773

  View details for PubMedID 33566009

  View details for PubMedCentralID PMC7336177

• Realizing split-pulse x-ray photon correlation spectroscopy to measure ultrafast dynamics in complex matter PHYSICAL REVIEW RESEARCH Sun, Y., Dunne, M., Fuoss, P., Robert, A., Zhu, D., Osaka, T., Yabashi, M., Sutton, M. 2020; 2 (2)

  View details for DOI 10.1103/PhysRevResearch.2.023099

  View details for Web of Science ID 000602777500004

• Design of an amplitude-splitting hard x-ray delay line with subnanoradian stability OPTICS LETTERS Li, H., Sun, Y., Sutton, M., Fuoss, P., Zhu, A. 2020; 45 (7): 2086–89

  Abstract

  We present the design and analysis of a hard x-ray split-delay optical arrangement that combines diffractive and crystal optics. Transmission gratings are employed to achieve the much-desired amplitude splitting and recombination of the beam. Asymmetric channel-cut crystals are utilized to tune the relative delay time. The use of a dispersion-compensation arrangement of the crystals allows the system to achieve subnanoradian pointing stability during a delay scan. It also minimizes wavefront distortion and preserves the pulse front and pulse duration. We analyze the performance of a prototype design that can cover a delay time range of 15 ps with a sub-20 fs time resolution at 10 keV. We anticipate that this system can fully satisfy the very demanding stability requirements for performing split-pulse x-ray photon correlation spectroscopy measurements for the investigation of fast atomic scale dynamics in complex disordered matter.

  View details for DOI 10.1364/OL.389977

  View details for Web of Science ID 000522794100124

  View details for PubMedID 32236074

• Speckle correlation as a monitor of X-ray free-electron laser induced crystal lattice deformation. Journal of synchrotron radiation Plumley, R. n., Sun, Y. n., Teitelbaum, S. n., Song, S. n., Sato, T. n., Chollet, M. n., Nelson, S. n., Wang, N. n., Sun, P. n., Robert, A. n., Fuoss, P. n., Sutton, M. n., Zhu, D. n. 2020; 27 (Pt 6): 1470–76

  Abstract

  X-ray free-electron lasers (X-FELs) present new opportunities to study ultrafast lattice dynamics in complex materials. While the unprecedented source brilliance enables high fidelity measurement of structural dynamics, it also raises experimental challenges related to the understanding and control of beam-induced irreversible structural changes in samples that can ultimately impact the interpretation of experimental results. This is also important for designing reliable high performance X-ray optical components. In this work, X-FEL beam-induced lattice alterations are investigated by measuring the shot-to-shot evolution of near-Bragg coherent scattering from a single crystalline germanium sample. It is shown that X-ray photon correlation analysis of sequential speckle patterns measurements can be used to monitor the nature and extent of lattice rearrangements. Abrupt, irreversible changes are observed following intermittent high-fluence monochromatic X-ray pulses, thus revealing the existence of a threshold response to X-FEL pulse intensity.

  View details for DOI 10.1107/S1600577520011509

  View details for PubMedID 33147171

• Compact hard x-ray split-delay system based on variable-gap channel-cut crystals OPTICS LETTERS Sun, Y., Wang, N., Song, S., Sun, P., Chollet, M., Sato, T., van Driel, T. B., Nelson, S., Plumley, R., Montana-Lopez, J., Teitelbaum, S. W., Haber, J., Hastings, J. B., Baron, A. R., Sutton, M., Fuoss, P. H., Robert, A., Zhu, D. 2019; 44 (10): 2582–85

  Abstract

  We present the concept and a prototypical implementation of a compact x-ray split-delay system that is capable of performing continuous on-the-fly delay scans over a range of ∼10  ps with sub-100 nanoradian pointing stability. The system consists of four channel-cut silicon crystals, two of which have gradually varying gap sizes from intentional 5 deg asymmetric cuts. The delay adjustment is realized by linear motions of these two monolithic varying-gap channel cuts, where the x-ray beam experiences pairs of anti-parallel reflections, and thus becomes less sensitive in output beam pointing to motion imperfections of the translation stages. The beam splitting is accomplished by polished crystal edges. A high degree of mutual coherence between the two branches at the focus is observed by analyzing small-angle coherent x-ray scattering patterns. We envision a wide range of applications including single-shot x-ray pulse temporal diagnostics, studies of high-intensity x-ray-matter interactions, as well as measurement of dynamics in disordered material systems using split-pulse x-ray photon correlation spectroscopy.

  View details for DOI 10.1364/OL.44.002582

  View details for Web of Science ID 000467906400050

  View details for PubMedID 31090737

• Higher-order modes at FELs: a machine interpretation Sun, P., Sun, Y., Zhu, D., Song, S., Li, H., Chollet, M., Seaberg, M., Hastings, J. B., Robert, A., Sutton, M., Feng, Y., Tschentscher, T., Patthey, L., Tiedtke, K., Zangrando, M. SPIE-INT SOC OPTICAL ENGINEERING. 2019

  View details for DOI 10.1117/12.2522912

  View details for Web of Science ID 000502119600001

• Design of a Compact Hard X-ray Split-Delay System Based on Variable-Gap Channelcut Crystals Sun, Y., Robert, A., Zhu, D., Gwo, S., Huang, D. J., Wei, D. H. AMER INST PHYSICS. 2019

  View details for DOI 10.1063/1.5084635

  View details for Web of Science ID 000472769500073

• Pulse intensity characterization of the LCLS nanosecond double-bunch mode of operation JOURNAL OF SYNCHROTRON RADIATION Sun, Y., Decker, F., Turner, J., Song, S., Robert, A., Zhu, D. 2018; 25: 642–49

  Abstract

  The recent demonstration of the `nanosecond double-bunch' operation mode, i.e. two X-ray pulses separated in time between 0.35 and hundreds of nanoseconds and by increments of 0.35 ns, offers new opportunities to investigate ultrafast dynamics in diverse systems of interest. However, in order to reach its full potential, this mode of operation requires the precise characterization of the intensity of each X-ray pulse within each pulse pair for any time separation. Here, a transmissive single-shot diagnostic that achieves this goal for time separations larger than 0.7 ns with a precision better than 5% is presented. It also provides real-time monitoring feedback to help tune the accelerator parameters to deliver double pulse intensity distributions optimized for specific experimental goals.

  View details for PubMedID 29714175

• Direct experimental observation of the gas density depression effect using a two-bunch X-ray FEL beam Feng, Y., Schafer, D. W., Song, S., Sun, Y., Zhu, D., Krzywinski, J., Robert, A., Wu, J., Decker, F. INT UNION CRYSTALLOGRAPHY. 2018: 145–50

  Abstract

  The experimental observation of the depression effect in gas devices designed for X-ray free-electron lasers (FELs) is reported. The measurements were carried out at the Linac Coherent Light Source using a two-bunch FEL beam at 6.5 keV with 122.5 ns separation passing through an argon gas cell. The relative intensities of the two pulses of the two-bunch beam were measured, after and before the gas cell, from X-ray scattering off thin targets by using fast diodes with sufficient temporal resolution. At a cell pressure of 140 hPa, it was found that the after-to-before ratio of the intensities of the second pulse was about 17% ± 6% higher than that of the first pulse, revealing lower effective attenuation of the gas cell due to heating by the first pulse and subsequent gas density reduction in the beam path. This measurement is important in guiding the design and/or mitigating the adverse effects in gas devices for high-repetition-rate FELs such as the LCLS-II and the European XFEL or other future high-repetition-rate upgrades to existing FEL facilities.

  View details for DOI 10.1107/S1600577517014278

  View details for Web of Science ID 000418593300022

  View details for PubMedID 29271764

  View details for PubMedCentralID PMC5741131

• Anatomically Defined and Functionally Distinct Dorsal Raphe Serotonin Sub-systems. Cell Ren, J. n., Friedmann, D. n., Xiong, J. n., Liu, C. D., Ferguson, B. R., Weerakkody, T. n., DeLoach, K. E., Ran, C. n., Pun, A. n., Sun, Y. n., Weissbourd, B. n., Neve, R. L., Huguenard, J. n., Horowitz, M. A., Luo, L. n. 2018

  Abstract

  The dorsal raphe (DR) constitutes a major serotonergic input to the forebrain and modulates diverse functions and brain states, including mood, anxiety, and sensory and motor functions. Most functional studies to date have treated DR serotonin neurons as a single population. Using viral-genetic methods, we found that subcortical- and cortical-projecting serotonin neurons have distinct cell-body distributions within the DR and differentially co-express a vesicular glutamate transporter. Further, amygdala- and frontal-cortex-projecting DR serotonin neurons have largely complementary whole-brain collateralization patterns, receive biased inputs from presynaptic partners, and exhibit opposite responses to aversive stimuli. Gain- and loss-of-function experiments suggest that amygdala-projecting DR serotonin neurons promote anxiety-like behavior, whereas frontal-cortex-projecting neurons promote active coping in the face of challenge. These results provide compelling evidence that the DR serotonin system contains parallel sub-systems that differ in input and output connectivity, physiological response properties, and behavioral functions.

  View details for PubMedID 30146164

• Development of a Hard X-ray Split-Delay System at the Linac Coherent Light Source Zhu, D., Sun, Y., Schafer, D. W., Shi, H., James, J. H., Gumerlock, K. L., Osier, T. O., Whitney, R., Zhang, L., Nicolas, J., Smith, B., Badara, A. H., Robert, A., Tschentscher, T., Patthey, L. SPIE-INT SOC OPTICAL ENGINEERING. 2017

  View details for DOI 10.1117/12.2265171

  View details for Web of Science ID 000406878700013

• Characterization of the LCLS "nanosecond two-bunch" mode for X-ray Speckle Visibility Spectroscopy experiments Sun, Y., Zhu, D., Song, S., Decker, F., Sutton, M., Ludwig, K., Roseker, W., Gruebel, G., Hruszkewycz, S., Stephenson, G., Fuoss, P. H., Robert, A., Tschentscher, T., Patthey, L. SPIE-INT SOC OPTICAL ENGINEERING. 2017

  View details for DOI 10.1117/12.2265454

  View details for Web of Science ID 000406878700011

• DESIGN OF A MULTI-DOF MOTION SYSTEM FOR X-RAY SPLIT AND DELAY Shi, H., Zhu, D., Schafer, D. W., Barada, A. H., Sun, Y., Zhang, L., Gumerlock, K. L., James, J. H., Osier, T. O., Whitney, R. A., Smith, B. E., Robert, A., ASME AMER SOC MECHANICAL ENGINEERS. 2017

  View details for Web of Science ID 000423244300031