@article{13998,
  abstract     = {The interaction of strong near-infrared (NIR) laser pulses with wide-bandgap dielectrics produces high harmonics in the extreme ultraviolet (XUV) wavelength range. These observations have opened up the possibility of attosecond metrology in solids, which would benefit from a precise measurement of the emission times of individual harmonics with respect to the NIR laser field. Here we show that, when high-harmonics are detected from the input surface of a magnesium oxide crystal, a bichromatic probing of the XUV emission shows a clear synchronization largely consistent with a semiclassical model of electron–hole recollisions in bulk solids. On the other hand, the bichromatic spectrogram of harmonics originating from the exit surface of the 200 μm-thick crystal is strongly modified, indicating the influence of laser field distortions during propagation. Our tracking of sub-cycle electron and hole re-collisions at XUV energies is relevant to the development of solid-state sources of attosecond pulses.},
  author       = {Vampa, Giulio and Lu, Jian and You, Yong Sing and Baykusheva, Denitsa Rangelova and Wu, Mengxi and Liu, Hanzhe and Schafer, Kenneth J and Gaarde, Mette B and Reis, David A and Ghimire, Shambhu},
  issn         = {1361-6455},
  journal      = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  keywords     = {Condensed Matter Physics, Atomic and Molecular Physics, and Optics},
  number       = {14},
  publisher    = {IOP Publishing},
  title        = {{Attosecond synchronization of extreme ultraviolet high harmonics from crystals}},
  doi          = {10.1088/1361-6455/ab8e56},
  volume       = {53},
  year         = {2020},
}

@article{14007,
  abstract     = {In a recent article by Hockett et al (2016 J. Phys. B: At. Mol. Opt. Phys. 49 095602), time delays arising in the context of molecular single-photon ionization are investigated from a theoretical point of view. We argue that one of the central equations given in this article is incorrect and present a reformulation that is consistent with the established treatment of angle-dependent scattering delays (Eisenbud 1948 PhD Thesis Princeton University; Wigner 1955 Phys. Rev. 98 145–7; Smith 1960 Phys. Rev. 118 349–6; Nussenzveig 1972 Phys. Rev. D 6 1534–42).},
  author       = {Baykusheva, Denitsa Rangelova and Wörner, Hans Jakob},
  issn         = {1361-6455},
  journal      = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  keywords     = {Condensed Matter Physics, Atomic and Molecular Physics, and Optics},
  number       = {7},
  publisher    = {IOP Publishing},
  title        = {{Comment on ‘Time delays in molecular photoionization’}},
  doi          = {10.1088/1361-6455/aa62b5},
  volume       = {50},
  year         = {2017},
}

@article{14021,
  abstract     = {We present the detailed analysis of a new two-pulse orientation scheme that achieves macroscopic field-free orientation at the high particle densities required for attosecond and high-harmonic spectroscopies (Kraus et al 2013 arXiv:1311.3923). Carbon monoxide molecules are oriented by combining one-colour and delayed two-colour non-resonant femtosecond laser pulses. High-harmonic generation is used to probe the oriented wave-packet dynamics and reveals that a very high degree of orientation (Nup/Ntotal = 0.73–0.82) is achieved. We further extend this approach to orienting carbonyl sulphide molecules. We show that the present two-pulse scheme selectively enhances orientation created by the hyperpolarizability interaction whereas the ionization-depletion mechanism plays no role. We further control and optimize orientation through the delay between the one- and two-colour pump pulses. Finally, we demonstrate a complementary encoding of electronic-structure features, such as shape resonances, in the even- and odd-harmonic spectrum. The achieved progress makes two-pulse field-free orientation an attractive tool for a broad class of time-resolved measurements.},
  author       = {Kraus, P M and Baykusheva, Denitsa Rangelova and Wörner, H J},
  issn         = {1361-6455},
  journal      = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  keywords     = {Condensed Matter Physics, Atomic and Molecular Physics, and Optics},
  number       = {12},
  publisher    = {IOP Publishing},
  title        = {{Two-pulse orientation dynamics and high-harmonic spectroscopy of strongly-oriented molecules}},
  doi          = {10.1088/0953-4075/47/12/124030},
  volume       = {47},
  year         = {2014},
}