Michael Pullen
Griffith University
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Publication
Featured researches published by Michael Pullen.
Nature Communications | 2015
Michael Pullen; Benjamin Wolter; Anh-Thu Le; Matthias Baudisch; M. Hemmer; Arne Senftleben; C. D. Schröter; Joachim Ullrich; R. Moshammer; C. D. Lin; Jens Biegert
Laser-induced electron diffraction is an evolving tabletop method that aims to image ultrafast structural changes in gas-phase polyatomic molecules with sub-Ångström spatial and femtosecond temporal resolutions. Here we demonstrate the retrieval of multiple bond lengths from a polyatomic molecule by simultaneously measuring the C–C and C–H bond lengths in aligned acetylene. Our approach takes the method beyond the hitherto achieved imaging of simple diatomic molecules and is based on the combination of a 160 kHz mid-infrared few-cycle laser source with full three-dimensional electron–ion coincidence detection. Our technique provides an accessible and robust route towards imaging ultrafast processes in complex gas-phase molecules with atto- to femto-second temporal resolution.
Science | 2016
Benjamin Wolter; Michael Pullen; Anh-Thu Le; Matthias Baudisch; K. Doblhoff-Dier; Arne Senftleben; M. Hemmer; C. D. Schröter; Joachim Ullrich; Thomas Pfeifer; R. Moshammer; Stefanie Gräfe; O. Vendrell; C. D. Lin; Jens Biegert
Acetylenes scission visualized by selfie Can molecules take pictures of themselves? That is more or less the principle underlying laser-induced electron diffraction (LIED): A laser field strips an electron from a molecule and then sends it back to report on the structure of the remaining ion. Wolter et al. applied this technique to acetylene to track the cleavage of its C–H bond after double ionization (see the Perspective by Ruan). They imaged the full structure of the molecule and also distinguished more rapid dissociative dynamics when it was oriented parallel rather than perpendicular to the LIED field. Science, this issue p. 308; see also p. 283 An electron transiently stripped from a molecule is used to image that molecules dissociation. Visualizing chemical reactions as they occur requires atomic spatial and femtosecond temporal resolution. Here, we report imaging of the molecular structure of acetylene (C2H2) 9 femtoseconds after ionization. Using mid-infrared laser–induced electron diffraction (LIED), we obtained snapshots as a proton departs the [C2H2]2+ ion. By introducing an additional laser field, we also demonstrate control over the ultrafast dissociation process and resolve different bond dynamics for molecules oriented parallel versus perpendicular to the LIED field. These measurements are in excellent agreement with a quantum chemical description of field-dressed molecular dynamics.
Optics Express | 2009
David Kielpinski; Michael Pullen; John Canning; Mark Stevenson; Paul S. Westbrook; Kenneth S. Feder
We generate mode-locked picosecond pulses near 1110 nm by spectrally slicing and reamplifying an octave-spanning supercontinuum source pumped at 1550 nm. The 1110 nm pulses are near transform-limited, with 1.7 ps duration over their 1.2 nm bandwidth, and exhibit high interpulse coherence. Both the supercontinuum source and the pulse synthesis system are implemented completely in fiber. The versatile source construction suggests that pulse synthesis from sliced supercontinuum may be a useful technique across the 1000 - 2000 nm wavelength range.
Physical Review A | 2014
Benjamin Wolter; C. Lemell; Matthias Baudisch; Michael Pullen; Xiao-Min Tong; M. Hemmer; Arne Senftleben; C. D. Schröter; Joachim H. Ullrich; R. Moshammer; Jens Biegert; Burgdörfer; Joachim
Atomic ionization by intense mid-infrared (mid-IR) pulses produces low electron energy features that the strong-field approximation, which is expected to be valid in the tunneling ionization regime characterized by small Keldysh parameters (
Nature Communications | 2016
Michael Pullen; Benjamin Wolter; Anh-Thu Le; Matthias Baudisch; Michele Sclafani; Hugo Pires; C. D. Schröter; Joachim Ullrich; R. Moshammer; Thomas Pfeifer; C. D. Lin; Jens Biegert
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Optics Letters | 2016
Matthias Baudisch; Benjamin Wolter; Michael Pullen; M. Hemmer; Jens Biegert
), cannot describe. These features include the low-energy structure (LES), the very-low-energy structure (VLES), and the more recently found zero-energy structure (ZES). They result from the interplay between the laser electric field and the atomic Coulomb field which controls the low-energy spectrum also for small
Physical Review Letters | 2016
William Carl Wallace; Omair Ghafur; C. Khurmi; Satya Sainadh U; James Edward Calvert; Dane Edward Laban; Michael Pullen; Klaus Bartschat; A N Grum-Grzhimailo; D. Wells; Harry M. Quiney; Xiao-Min Tong; Igor Litvinyuk; Robert Sang; David Kielpinski
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Optics Letters | 2011
Michael Pullen; William Carl Wallace; Dane Edward Laban; Adam James Palmer; G F Hanne; A N Grum-Grzhimailo; Brant Abeln; Klaus Bartschat; Daniel Weflen; Igor Ivanov; Anatoli Kheifets; Harry M. Quiney; Igor Litvinyuk; Robert Sang; David Kielpinski
. In the present joint experimental and theoretical study we investigate the vectorial momentum spectrum at very low energies. Using a reaction microscope optimized for the detection of very low energy electrons, we have performed a thorough study of the three-dimensional momentum spectrum well below 1 eV. Our measurements are complemented by quantum and classical simulations, which allow for an interpretation of the LES, VLES and of the newly identified ZES in terms of two-dimensional Coulomb focusing and recapture into Rydberg states, respectively.
Physical Review A | 2017
Michael Pullen; Benjamin Wolter; Xu Wang; Xiao-Min Tong; Michele Sclafani; Matthias Baudisch; Hugo Pires; C. D. Schröter; Joachim Ullrich; Thomas Pfeifer; R. Moshammer; J. H. Eberly; Jens Biegert
The ability to directly follow and time-resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser-induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as πg) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction to these findings, that the orientation and shape of molecular orbitals presents no impediment for retrieving molecular structure with adequate sampling of the momentum transfer space. We overcome previous issues by showcasing retrieval of the structure of randomly oriented O2 and C2H2 molecules, with πg and πu symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. While this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms.
Journal of Physics B | 2014
Michael Pullen; Judith Dura; Benjamin Wolter; Matthias Baudisch; M. Hemmer; Nicolas Camus; Arne Senftleben; Claus Dieter Schroeter; R. Moshammer; Joachim Ullrich; Jens Biegert
Many experimental investigations demand synchronized pulses at various wavelengths, ideally with very short pulse duration and high repetition rate. Here we describe a femtosecond multi-color optical parametric chirped pulse amplifier (OPCPA) with simultaneous outputs from the deep-UV to the mid-IR with optical synchronization. The high repetition rate of 160 kHz is well suited to compensate for low interaction probability or low cross section in strong-field interactions. Our source features high peak powers in the tens to hundreds of MW regime with pulse durations below 110 fs, which is ideal for pump-probe experiments of nonlinear and strong-field physics. We demonstrate its utility by strong-field ionization experiments of xenon in the near- to mid-IR.