Femtosecond photoelectron diffraction on laser-aligned molecules: Towards time-resolved imaging of molecular structure

Boll, Rebecca; Anielski, Denis; Bostedt, Christoph; Bozek, John D.; Christensen, Lars Rune; Coffee, Ryan; De, S.; Decleva, Piero; Epp, Sascha W.; Erk, Benjamin; Foucar, L.; Krasniqi, Faton; Küpper, Jochen; Rouzée, Arnaud; Rudek, Benedikt; Rudenko, Artem; Schorb, Sebastian; Stapelfeldt, Henrik; Stener, Mauro; Stern, Stephan; Techert, Simone; Trippel, Sebastian; Vrakking, Marc J. J.; Ullrich, J.; Rolles, Daniel

doi:10.1103/physreva.88.061402

Cited by 83 publications

(105 citation statements)

References 35 publications

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“…With the currently fast progressing development of pulsed light sources based on higherharmonic generation (HHG) [5], reaching photon energies in the uv and soft x-ray region, there is also a potential to use photoelectron diffraction in a pumpprobe scheme for studying structural dynamics at surfaces. Such experiments have already been successfully performed for laser-aligned molecules in the gas phase using free-electron laser pulses [6].…”

Section: Introductionmentioning

confidence: 99%

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Greif

Castiglioni

Becker‐Koch

et al. 2014

Journal of Electron Spectroscopy and Related Phenomena

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An efficient and fast way to measure photoelectron diffraction data over the full 2 angular range with high data point density is presented, taking advantage of the massive parallel detection capabilities of modern two-dimensional electron detectors. We introduce generic routines for data binning and for the mapping of the detector signal onto emission angles. X-ray photoelectron diffraction patterns taken from Bi(1 1 1) with the new detection scheme are compared to data sets taken with a conventional hemispherical analyzer equipped with a channeltron detector. As a result, the data acquisition time can be reduced by roughly a factor of ten while obtaining comparable if not superior data quality. The sampling technique is extended to UV-excited angle-resolved photoelectron spectroscopy as illustrated by a mapping of the Fermi surface of Cu (1 1 1 AbstractAn efficient and fast way to measure photoelectron diffraction data over the full 2π angular range with high data point density is presented, taking advantage of the massive parallel detection capabilities of modern two-dimensional electron detectors. We introduce generic routines for data binning and for the mapping of the detector signal onto emission angles. X-ray photoelectron diffraction patterns taken from Bi(111) with the new detection scheme are compared to data sets taken with a conventional hemispherical analyzer equipped with a channeltron detector. As a result, the data acquisition time can be reduced by roughly a factor of ten while obtaining comparable if not superior data quality.The sampling technique is extended to uv-excited angle-resolved photoelectron spectroscopy as illustrated by a mapping of the Fermi surface of Cu(111).

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Section: Introductionmentioning

confidence: 99%

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Greif

Castiglioni

Becker‐Koch

et al. 2014

Journal of Electron Spectroscopy and Related Phenomena

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“…Since x-ray diffraction suffers from weak elastic scattering cross sections, to take advantage of the currently available and future short extreme ultraviolet (XUV) or x-ray pulses, different schemes have been proposed for gas-phase molecules which rely on photoelectron diffraction [21][22][23][24][25][26][27][28][29]. In contrast to the TRPES method that probes valence electrons, photoelectron diffraction with localized inner-shell electrons is capable of directly imaging atomic positions.…”

Section: Introductionmentioning

confidence: 99%

Probing and extracting the structure of vibratingSF6molecules with inner-shell photoelectrons

et al. 2016

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We propose a scheme for probing the structure of vibrating molecules with photoelectrons generated from ultrashort soft-x-ray pulses. As an example we analyze below-100-eV photoelectrons liberated from the S(2p) orbital of vibrating SF 6 molecules to image very small structural changes of molecular vibration. In particular, photoionization cross sections and photoelectron angular distributions (PAD) at nonequilibrium geometries can be retrieved accurately with photoelectrons near the shape resonance at 13 eV. This is achieved with a pump-probe scheme, in which the symmetric stretch mode is first Raman excited predominantly by a relatively short laser pulse and then later probed at different time delays by a few-femtosecond soft-x-ray pulse with photon energy near 200 eV.

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“…These MFPADs show holographic structures due to the interference of the direct and the scattered parts of the outgoing-electron wave. Especially in the case of core excitations above an absorption edge, e.g., F(1s) photoionization, this hologram provides chemical sensitivity for probing of the local structure around the ionized atom [21]- [23]. These experiments will be compared to modern imaging experiments utilizing tabletop laser systems, such as MFPAD measurements following strong-field ionization [26], [27], laser-induced electron diffraction [28], or high-harmonic spectroscopy [29].…”

mentioning

confidence: 99%

“…These include the direct x-ray-diffractive imaging of aligned isolated gas-phase molecules [19], [20] and photoelectronholography approaches, which are implemented as imaging of molecular-frame photoelectron angular distributions (MF-PAD) [21]- [23]. In these first benchmark imaging experiments, we have exploited cold molecular beams from state-of-theart pulsed valves.…”

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confidence: 99%

Imaging molecular structure and dynamics utilizing x-ray free-electron-laser sources

Küpper

2015

2015 IEEE Photonics Conference (IPC)

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Abstract-Imaging controlled molecules with ultrashort xray pulses from free-electron lasers enables the recording of "molecular movies", i.e., snapshots of molecules at work, with spatial (picometer) and temporal (femtosecond) atomic resolution.Hard-x-ray free-electron lasers (FELs) provide femtosecond-duration pulses of x-rays with unprecedented brilliance [1], [2]. These enable the study of ultrafast chemical dynamics of isolated molecules in the gas phase using diffractive-imaging methods [3]- [7]. We exploit various imaging approaches to understand the intrinsic molecular structure and function, which is at the very heart of the chemical and molecular sciences.Experiments that allow for the creation of structurally pure samples and, subsequently, for the investigation of their intrinsic molecular dynamics and chemical function have developed tremendously over the last few decades, although "there's plenty of room at the bottom" -for better control as well as for further applications. We detail the use of inhomogeneous electric fields for the manipulation of neutral molecules in the gas-phase, i.e., for the separation of complex molecules according to size, structural isomer, and quantum state [8]- [12]. These quantum-state-selected samples allow for very strong degrees of alignment and orientation [9], [13]- [17]. The produced ensembles of structurally sorted and fixed-inspace molecules are well-suited for imaging experiments, as the availability of many identical molecules in the camera's frame of reference allows for direct, experimental averaging of the recorded signal until it is above noise.We have performed a number of imaging experiments at the Linac Coherent Light Source (LCLS) at SLAC [2] and the Free-Electron Laser in Hamburg (FLASH) at DESY [18]. These include the direct x-ray-diffractive imaging of aligned isolated gas-phase molecules [19], [20] and photoelectronholography approaches, which are implemented as imaging of molecular-frame photoelectron angular distributions (MF-PAD) [21]-[23]. In these first benchmark imaging experiments, we have exploited cold molecular beams from state-of-theart pulsed valves. These beams were further purified using the electric deflector [24], which spatially disperses the beam according to the molecules' quantum states and separates the molecules from the atomic seed gas. The quantum-state selected samples were laser aligned or mixed-field oriented using nanosecond-pulsed Nd:YAG lasers or stretched pulses from amplified Ti:Sapphire laser systems. The latter allows to generate strong alignment and orientation at full FEL repetition rates [15], [25].

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Femtosecond photoelectron diffraction on laser-aligned molecules: Towards time-resolved imaging of molecular structure

Cited by 83 publications

References 35 publications

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Acquisition of photoelectron diffraction patterns with a two-dimensional wide-angle electron analyzer

Probing and extracting the structure of vibratingSF6molecules with inner-shell photoelectrons

Imaging molecular structure and dynamics utilizing x-ray free-electron-laser sources

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