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Xiong Y, Borne K, Carrascosa AM, Saha SK, Wilkin KJ, Yang M, Bhattacharyya S, Chen K, Du W, Ma L, Marshall N, Nunes JPF, Pathak S, Phelps Z, Xu X, Yong H, Lopata K, Weber PM, Rudenko A, Rolles D, Centurion M. Strong-field induced fragmentation and isomerization of toluene probed by ultrafast femtosecond electron diffraction and mass spectrometry. Faraday Discuss 2021; 228:39-59. [PMID: 33565561 DOI: 10.1039/d0fd00125b] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We investigate the fragmentation and isomerization of toluene molecules induced by strong-field ionization with a femtosecond near-infrared laser pulse. Momentum-resolved coincidence time-of-flight ion mass spectrometry is used to determine the relative yield of different ionic products and fragmentation channels as a function of laser intensity. Ultrafast electron diffraction is used to capture the structure of the ions formed on a picosecond time scale by comparing the diffraction signal with theoretical predictions. Through the combination of the two measurements and theory, we are able to determine the main fragmentation channels and to distinguish between ions with identical mass but different structures. In addition, our diffraction measurements show that the independent atom model, which is widely used to analyze electron diffraction patterns, is not a good approximation for diffraction from ions. We show that the diffraction data is in very good agreement with ab initio scattering calculations.
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Affiliation(s)
- Yanwei Xiong
- University of Nebraska - Lincoln, Lincoln, Nebraska, USA.
| | - Kurtis Borne
- Kansas State University - Manhattan, Kansas, USA
| | | | | | - Kyle J Wilkin
- University of Nebraska - Lincoln, Lincoln, Nebraska, USA.
| | - Mengqi Yang
- Louisiana State University, Baton Rouge, Louisiana, USA
| | | | - Keyu Chen
- Kansas State University - Manhattan, Kansas, USA
| | - Wenpeng Du
- Brown University - Providence, Rhode Island, USA
| | - Lingyu Ma
- Brown University - Providence, Rhode Island, USA
| | | | | | | | - Zane Phelps
- Kansas State University - Manhattan, Kansas, USA
| | - Xuan Xu
- Brown University - Providence, Rhode Island, USA
| | - Haiwang Yong
- Brown University - Providence, Rhode Island, USA
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Yang J, Guehr M, Vecchione T, Robinson MS, Li R, Hartmann N, Shen X, Coffee R, Corbett J, Fry A, Gaffney K, Gorkhover T, Hast C, Jobe K, Makasyuk I, Reid A, Robinson J, Vetter S, Wang F, Weathersby S, Yoneda C, Wang X, Centurion M. Femtosecond gas phase electron diffraction with MeV electrons. Faraday Discuss 2016; 194:563-581. [PMID: 27711826 DOI: 10.1039/c6fd00071a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present results on ultrafast gas electron diffraction (UGED) experiments with femtosecond resolution using the MeV electron gun at SLAC National Accelerator Laboratory. UGED is a promising method to investigate molecular dynamics in the gas phase because electron pulses can probe the structure with a high spatial resolution. Until recently, however, it was not possible for UGED to reach the relevant timescale for the motion of the nuclei during a molecular reaction. Using MeV electron pulses has allowed us to overcome the main challenges in reaching femtosecond resolution, namely delivering short electron pulses on a gas target, overcoming the effect of velocity mismatch between pump laser pulses and the probe electron pulses, and maintaining a low timing jitter. At electron kinetic energies above 3 MeV, the velocity mismatch between laser and electron pulses becomes negligible. The relativistic electrons are also less susceptible to temporal broadening due to the Coulomb force. One of the challenges of diffraction with relativistic electrons is that the small de Broglie wavelength results in very small diffraction angles. In this paper we describe the new setup and its characterization, including capturing static diffraction patterns of molecules in the gas phase, finding time-zero with sub-picosecond accuracy and first time-resolved diffraction experiments. The new device can achieve a temporal resolution of 100 fs root-mean-square, and sub-angstrom spatial resolution. The collimation of the beam is sufficient to measure the diffraction pattern, and the transverse coherence is on the order of 2 nm. Currently, the temporal resolution is limited both by the pulse duration of the electron pulse on target and by the timing jitter, while the spatial resolution is limited by the average electron beam current and the signal-to-noise ratio of the detection system. We also discuss plans for improving both the temporal resolution and the spatial resolution.
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Affiliation(s)
- Jie Yang
- University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
| | - Markus Guehr
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA and Physics and Astronomy, Potsdam University, Potsdam, 14476, Germany
| | | | - Matthew S Robinson
- University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
| | - Renkai Li
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Nick Hartmann
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Ryan Coffee
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Jeff Corbett
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Alan Fry
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Kelly Gaffney
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Tais Gorkhover
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Carsten Hast
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Keith Jobe
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Igor Makasyuk
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Alexander Reid
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Joseph Robinson
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Sharon Vetter
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Fenglin Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | | | - Charles Yoneda
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Martin Centurion
- University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA.
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Scoby CM, Li RK, Musumeci P. Effect of an ultrafast laser induced plasma on a relativistic electron beam to determine temporal overlap in pump-probe experiments. Ultramicroscopy 2012; 127:14-8. [PMID: 22951263 DOI: 10.1016/j.ultramic.2012.07.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper we report on a simple and robust method to measure the absolute temporal overlap of the laser and the electron beam at the sample based on the effect of a laser induced plasma on the electron beam transverse distribution, successfully extending a similar method from keV to MeV electron beams. By pumping a standard copper TEM grid to form the plasma, we gain timing information independent of the sample under study. In experiments discussed here the optical delay to achieve temporal overlap between the pump electron beam and probe laser can be determined with ~1 ps precision.
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Affiliation(s)
- Cheyne M Scoby
- UCLA Department of Physics, 475 Portola Plaza, Los Angeles, CA 90095-1547, USA.
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