@article{brown_rmt_2020,
	title = {{RMT}: {R}-matrix with time-dependence. {Solving} the semi-relativistic, time-dependent {Schrödinger} equation for general, multielectron atoms and molecules in intense, ultrashort, arbitrarily polarized laser pulses},
	volume = {250},
	issn = {0010-4655},
	shorttitle = {{RMT}},
	url = {https://www.sciencedirect.com/science/article/pii/S0010465519303856},
	doi = {10.1016/j.cpc.2019.107062},
	abstract = {RMT is a programme which solves the time-dependent Schrödinger equation for general, multielectron atoms, ions and molecules interacting with laser light. As such it can be used to model ionization (single-photon, multiphoton and strong-field), recollision (high-harmonic generation, strong-field rescattering) and, more generally, absorption or scattering processes with a full account of the multielectron correlation effects in a time-dependent manner. Calculations can be performed for targets interacting with ultrashort, intense laser pulses of long wavelength and arbitrary polarization. Calculations for atoms can optionally include the Breit–Pauli correction terms for the description of relativistic (in particular, spin–orbit) effects.
Program summary
Program Title: (RMT) R-matrix with time-dependence Program Files doi: http://dx.doi.org/10.17632/3ptyfg2bmx.1 Licensing provisions: GPLv3 Programming language: Fortran Nature of problem: The interaction of laser light with matter can be modelled with the time-dependent Schrödinger equation (TDSE). The solution of the TDSE for general, multielectron atomic and molecular systems is computationally demanding, and has previously been limited either to particular laser wavelengths and intensities, or to simple, few-electron cases. RMT overcomes this limitation by using a general approach to modelling dynamics in atoms and molecules which is applicable to multielectron systems and a wide range of perturbative and non-perturbative phenomena. Solution method: We use the R-matrix paradigm, partitioning the interaction region into an ‘inner’ and an ‘outer’ region. In the inner region (within some small radius of the nucleus/nuclei), full account is taken of all multielectron interactions including electron exchange and correlation. In the outer region, far from the nucleus/nuclei, these are neglected and a single, ionized electron moves in the long-range potential of the residual ionic system and the laser field. The key computational aspect of the RMT approach is the use of a different numerical scheme in each region, facilitating efficient parallelization without sacrificing accuracy. Given an initial wavefunction and the electric field of the driving laser pulse, the wavefunction for all subsequent times and the associated observables are computed using an explicit, Arnoldi propagator method. Additional comments including restrictions and unusual features: The description of the atomic/molecular structure is provided from other, time-independent R-matrix codes [1], [2], [3], and the capabilities (in terms of structure) are, in some sense, inherited therefrom. Thus, the atomic calculations can optionally include Breit–Pauli relativistic corrections to the Hamiltonian, in order to account for the spin–orbit effect. However, no such capability exists for the molecular case. Furthermore, the fixed-nuclei approximation is adopted in the molecular calculations (so nuclear motion is neglected). Similarly, all calculations are restricted to the description of a single electron in the outer region, and consequently the study of double-ionization phenomena is not yet within the capabilities of the method. Finally, the parallel strategy employed necessitates the use of at least two (and usually many more) computer cores. As a result, there is no option for serial calculations and, for most realistic cases, a massively parallel architecture (several hundred cores) will be required. Program repository available at: https://gitlab.com/Uk-amor/RMT References [1] C. P. Ballance Parallel R-matrix codes, http://connorb.freeshell.org. [2] R-matrix II codes, http://gitlab.com/uk-amor/rmt/rmatrixii. [3] Z. Mašín et al UKRmol+: a suite for modelling of electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method, Comput. Phys. Commun., accepted, http://dx.doi.org/10.1016/j.cpc.2019.107092.},
	language = {en},
	urldate = {2022-11-09},
	journal = {Computer Physics Communications},
	author = {Brown, Andrew C. and Armstrong, Gregory S. J. and Benda, Jakub and Clarke, Daniel D. A. and Wragg, Jack and Hamilton, Kathryn R. and Mašín, Zdeněk and Gorfinkiel, Jimena D. and van der Hart, Hugo W.},
	month = may,
	year = {2020},
	note = {tex.ids= brown2019RMTRmatrixTimedependence
arXiv: 1905.06156},
	keywords = {\#nosource, -matrix, Attosecond physics, Electron correlation, Ionization, Strong-field physics, Ultrafast physics},
	pages = {107062},
}

RMT is a programme which solves the time-dependent Schrödinger equation for general, multielectron atoms, ions and molecules interacting with laser light. As such it can be used to model ionization (single-photon, multiphoton and strong-field), recollision (high-harmonic generation, strong-field rescattering) and, more generally, absorption or scattering processes with a full account of the multielectron correlation effects in a time-dependent manner. Calculations can be performed for targets interacting with ultrashort, intense laser pulses of long wavelength and arbitrary polarization. Calculations for atoms can optionally include the Breit–Pauli correction terms for the description of relativistic (in particular, spin–orbit) effects. Program summary Program Title: (RMT) R-matrix with time-dependence Program Files doi: http://dx.doi.org/10.17632/3ptyfg2bmx.1 Licensing provisions: GPLv3 Programming language: Fortran Nature of problem: The interaction of laser light with matter can be modelled with the time-dependent Schrödinger equation (TDSE). The solution of the TDSE for general, multielectron atomic and molecular systems is computationally demanding, and has previously been limited either to particular laser wavelengths and intensities, or to simple, few-electron cases. RMT overcomes this limitation by using a general approach to modelling dynamics in atoms and molecules which is applicable to multielectron systems and a wide range of perturbative and non-perturbative phenomena. Solution method: We use the R-matrix paradigm, partitioning the interaction region into an ‘inner’ and an ‘outer’ region. In the inner region (within some small radius of the nucleus/nuclei), full account is taken of all multielectron interactions including electron exchange and correlation. In the outer region, far from the nucleus/nuclei, these are neglected and a single, ionized electron moves in the long-range potential of the residual ionic system and the laser field. The key computational aspect of the RMT approach is the use of a different numerical scheme in each region, facilitating efficient parallelization without sacrificing accuracy. Given an initial wavefunction and the electric field of the driving laser pulse, the wavefunction for all subsequent times and the associated observables are computed using an explicit, Arnoldi propagator method. Additional comments including restrictions and unusual features: The description of the atomic/molecular structure is provided from other, time-independent R-matrix codes [1], [2], [3], and the capabilities (in terms of structure) are, in some sense, inherited therefrom. Thus, the atomic calculations can optionally include Breit–Pauli relativistic corrections to the Hamiltonian, in order to account for the spin–orbit effect. However, no such capability exists for the molecular case. Furthermore, the fixed-nuclei approximation is adopted in the molecular calculations (so nuclear motion is neglected). Similarly, all calculations are restricted to the description of a single electron in the outer region, and consequently the study of double-ionization phenomena is not yet within the capabilities of the method. Finally, the parallel strategy employed necessitates the use of at least two (and usually many more) computer cores. As a result, there is no option for serial calculations and, for most realistic cases, a massively parallel architecture (several hundred cores) will be required. Program repository available at: https://gitlab.com/Uk-amor/RMT References [1] C. P. Ballance Parallel R-matrix codes, http://connorb.freeshell.org. [2] R-matrix II codes, http://gitlab.com/uk-amor/rmt/rmatrixii. [3] Z. Mašín et al UKRmol+: a suite for modelling of electronic processes in molecules interacting with electrons, positrons and photons using the R-matrix method, Comput. Phys. Commun., accepted, http://dx.doi.org/10.1016/j.cpc.2019.107092.

@article{driver_attosecond_2019,
	title = {Attosecond transient absorption spooktroscopy: a ghost imaging approach to ultrafast absorption spectroscopy},
	doi = {10.1039/c9cp03951a},
	abstract = {The recent demonstration of isolated attosecond pulses from an X-ray free-electron laser (XFEL) opens the possibility for probing ultrafast electron dynamics at X-ray wavelengths. An established experimental method for probing ultrafast dynamics is X-ray transient absorption spectroscopy, where the X-ray absorption spectrum is measured by scanning the central photon energy and recording the resultant photoproducts. The spectral bandwidth inherent to attosecond pulses is wide compared to the resonant features typically probed, which generally precludes the application of this technique in the attosecond regime. In this paper we propose and demonstrate a new technique to conduct transient absorption spectroscopy with broad bandwidth attosecond pulses with the aid of ghost imaging, recovering sub-bandwidth resolution in photoproduct-based absorption measurements.},
	urldate = {2020-01-27},
	author = {Driver, Taran and Li, Siqi and Champenois, Elio G and Duris, Joseph and Ratner, Daniel and Lane, Thomas J and Rosenberger, Philipp and Al-Haddad, Andre and Averbukh, Vitali and Barnard, Toby and Berrah, Nora and Bostedt, Christoph and Bucksbaum, Philip H and Coffee, Ryan and Dimauro, Louis F and Fang, Li and Garratt, Douglas and Gatton, Averell and Guo, Zhaoheng and Hartmann, Gregor and Haxton, Daniel and Helml, Wolfram and Huang, Zhirong and Laforge, Aaron and Kamalov, Andrei and Kling, Matthias F and Knurr, Jonas and Lin, Ming-Fu and Lutman, Alberto A and Macarthur, James P and Marangos, Jon P and Nantel, Megan and Natan, Adi and Obaid, Razib and O'neal, Jordan T and Shivaram, Niranjan H and Schori, Aviad and Walter, Peter and Wang, Anna Li and Wolf, Thomas J A and Marinelli, Agostino and Cryan, James P},
	year = {2019},
	note = {tex.ids: driver2020AttosecondTransientAbsorption
publisher: The Royal Society of Chemistry},
}

The recent demonstration of isolated attosecond pulses from an X-ray free-electron laser (XFEL) opens the possibility for probing ultrafast electron dynamics at X-ray wavelengths. An established experimental method for probing ultrafast dynamics is X-ray transient absorption spectroscopy, where the X-ray absorption spectrum is measured by scanning the central photon energy and recording the resultant photoproducts. The spectral bandwidth inherent to attosecond pulses is wide compared to the resonant features typically probed, which generally precludes the application of this technique in the attosecond regime. In this paper we propose and demonstrate a new technique to conduct transient absorption spectroscopy with broad bandwidth attosecond pulses with the aid of ghost imaging, recovering sub-bandwidth resolution in photoproduct-based absorption measurements.

@article{masin_ukrmol_2019,
	title = {{UKRmol}+: {A} suite for modelling electronic processes in molecules interacting with electrons, positrons and photons using the {R}-matrix method},
	issn = {00104655},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0010465519303972},
	doi = {10.1016/j.cpc.2019.107092},
	urldate = {2020-01-21},
	journal = {Computer Physics Communications},
	author = {Mašín, Zdeněk and Benda, Jakub and Gorfinkiel, Jimena D. and Harvey, Alex G. and Tennyson, Jonathan},
	month = dec,
	year = {2019},
	pages = {107092},
}

@article{larsen_resonance_2018,
	title = {Resonance signatures in the body-frame valence photoionization of {CF} 4},
	volume = {20},
	doi = {10.1039/c8cp03637c},
	urldate = {2020-01-27},
	journal = {Phys. Chem. Chem. Phys},
	author = {Larsen, K A and Trevisan, C S and Lucchese, R R and Heck, S and Iskandar, W and Champenois, E and Gatton, A and Moshammer, R and Strom, R and Severt, T and Jochim, B and Reedy, D and Weller, M and Landers, A L and Williams, J B and Ben-Itzhak, I and Dö, R and Slaughter, D and Mccurdy, C W and Weber, Th and Rescigno, T N},
	year = {2018},
	pages = {21075},
}

@article{suzuki_communication_2018,
	title = {Communication: {Photoionization} of degenerate orbitals for randomly oriented molecules: {The} effect of time-reversal symmetry on recoil-ion momentum angular distributions},
	volume = {148},
	issn = {00219606},
	doi = {10.1063/1.5026181},
	abstract = {The photoelectron asymmetry parameter β, which characterizes the direction of electrons ejected from a randomly oriented molecular ensemble by linearly polarized light, is investigated for degenerate orbitals. We show that β is totally symmetric under the symmetry operation of the point group of a molecule, and it has mixed properties under time reversal. Therefore, all degenerate molecular orbitals, except for the case of degeneracy due to time reversal, have the same β (Wigner-Eckart theorem). The exceptions are e-type complex orbitals of the C n , S n , C nh , T, and T h point groups, and calculations on boric acid (C 3h symmetry) are performed as an example. However, including those point groups, all degenerate orbitals have the same β if those orbitals are real. We discuss the implications of this operator formalism for molecular alignment and photoelectron circular dichroism.},
	number = {15},
	urldate = {2020-01-21},
	journal = {Journal of Chemical Physics},
	author = {Suzuki, Yoshi Ichi},
	month = apr,
	year = {2018},
	note = {Publisher: American Institute of Physics Inc.},
}

The photoelectron asymmetry parameter β, which characterizes the direction of electrons ejected from a randomly oriented molecular ensemble by linearly polarized light, is investigated for degenerate orbitals. We show that β is totally symmetric under the symmetry operation of the point group of a molecule, and it has mixed properties under time reversal. Therefore, all degenerate molecular orbitals, except for the case of degeneracy due to time reversal, have the same β (Wigner-Eckart theorem). The exceptions are e-type complex orbitals of the C n , S n , C nh , T, and T h point groups, and calculations on boric acid (C 3h symmetry) are performed as an example. However, including those point groups, all degenerate orbitals have the same β if those orbitals are real. We discuss the implications of this operator formalism for molecular alignment and photoelectron circular dichroism.

@article{Yagishita2015,
	title = {Photoelectron angular distributions from single oriented molecules: {Past}, present and future},
	volume = {200},
	issn = {03682048},
	url = {http://www.sciencedirect.com/science/article/pii/S0368204815000882},
	doi = {10.1016/j.elspec.2015.04.016},
	abstract = {We provide a simple physical picture of the molecular frame photoelectron angular distributions (MFPAD). In the energy region near the ionization threshold, it has been demonstrated that the MFPAD can be understood by the interference between several partial waves. In the energy region higher than 100eV, the MFPAD has been interpreted by the intra-molecule photoelectron diffraction. That is, it has been verified that multiple-scattering X-ray photoelectron diffraction (XPD) theory is a promising probe of the dynamical process. Therefore, we look into the future: a new methodology for molecular structure determination will be applied to determine ultrafast molecular structure changes due to ultrafast core-level XPD imaging from within, as demonstrated in our simulations for elemental processes of photo-induced unimolecular reactions.},
	journal = {Journal of Electron Spectroscopy and Related Phenomena},
	author = {Yagishita, Akira},
	year = {2015},
	note = {Publisher: Elsevier B.V.},
	keywords = {MFPAD, XFEL, XPD},
	pages = {247--256},
}

We provide a simple physical picture of the molecular frame photoelectron angular distributions (MFPAD). In the energy region near the ionization threshold, it has been demonstrated that the MFPAD can be understood by the interference between several partial waves. In the energy region higher than 100eV, the MFPAD has been interpreted by the intra-molecule photoelectron diffraction. That is, it has been verified that multiple-scattering X-ray photoelectron diffraction (XPD) theory is a promising probe of the dynamical process. Therefore, we look into the future: a new methodology for molecular structure determination will be applied to determine ultrafast molecular structure changes due to ultrafast core-level XPD imaging from within, as demonstrated in our simulations for elemental processes of photo-induced unimolecular reactions.

@article{Yagishita2005,
	title = {Photoelectron angular distributions from fixed-in-space molecules},
	volume = {142},
	issn = {03682048},
	url = {http://linkinghub.elsevier.com/retrieve/pii/S0368204804003639},
	doi = {10.1016/j.elspec.2004.09.005},
	number = {3},
	urldate = {2014-11-07},
	journal = {Journal of Electron Spectroscopy and Related Phenomena},
	author = {Yagishita, Akira and Hosaka, Kouichi and Adachi, Jun-Ichi},
	month = mar,
	year = {2005},
	keywords = {\#nosource, electric-dipole matrix element, fixed-molecule pad, shape resonance},
	pages = {295--312},
}

@article{Shigemasa1995,
	title = {Angular {Distributions} of 1sσ {Photoelectrons} from {Fixed}-in-{Space} {N2}},
	volume = {74},
	issn = {0031-9007},
	url = {https://link.aps.org/doi/10.1103/PhysRevLett.74.359},
	doi = {10.1103/PhysRevLett.74.359},
	abstract = {The angular distributions of 1so-photoelectrons from N2 molecules held fixed in space have been measured around the or* shape resonance for the first time, The angular distributions have been very rich in structure, which are completely different from usual photoelectron angular distributions from randomly oriented molecules, as predicted by Dill. The orbital angular momentum properties of the 1scr photoelectrons around the o. * shape resonance have been made clear from the angular distribution patterns. PACS numbers: 33.80.Eh, 33.90.+h Molecular K-shell spectra are known to depart remark-ably from corresponding atomic spectra [1]. Specifically, above the K edge there is a broad band of enhanced pho-toabsorption in place of the smooth monotonic decrease one might expect. The novel feature, so called shape res-onance, results from the interaction between the photo-electron escaping from the K shell and the anisotropic molecular field [2]. Direct study of the orbital angular momentum properties of the photoelectrons in the shape resonance is not pos-sible by conventional gas-phase photoelectron angular distribution studies, owing to the random orientations of the molecules. If, however, the molecules have a definite orientation, the angular distributions of photoelectrons ejected by the electric-dipole interaction has the general form [3] 2{\textasciitilde}max g {\textasciitilde}KM' KM(0 tt') @=0 M where the angles (0, tb) are measured from the molecule g axis, I " is the maximum orbital angular momentum component of the outgoing photoelectron, and Y{\textasciitilde}M are the spherical harmonics. Thus, such photoelectron angular distributions of fixed-in-space molecules can offer a direct probe of the orbital angular momentum composition of the molecular photoelectrons. In the limited case, the angular distribution of photoelectrons from oriented H2 [4], CO [5], and N2 and CO [6] molecules were predicted by three groups. The present experiment has been undertaken to study the orbital angular momentum properties of the photo-electrons in a prototype molecular shape resonance — the o. * shape resonance of nitrogen molecules. In this Let-ter, we present the first experimental results on the an-gular distributions of lsd-photoelectrons ejected from Nz molecules held fixed in space. The photoionization pro-cesses of fixed-in-space molecules in a gas phase can be realized by detecting photoelectrons in coincidence with fragment ions as reported by Golovin et al. [7,8]. Since the dissociation time of the molecular ions produced by a subsequent Auger decay of the K-shell vacancy is much shorter than the molecular rotation period, the emission direction of the fragment ion is considered to be equiva-lent to the molecular orientation at a moment of absorp-tion of a photon. The experiments have been carried out on beam line BL-28, supplying the synchrotron radiation emitted from an undulator [9] inserted in the 2.5 GeV positron stor-age ring at the Photon Factory. The undulator radia-tion, monochromatized with a 10 m grazing incidence monochromator [10], was focused onto an effusive beam of the sample gas at the center of the ionization region of the experimental chamber. The entrance and exit slit openings of the monochromator were both set to 50 p, m. The expected energy resolution was about 0.6 eV at h p = 400 eV. The diameter of the photon beam spot at the sam-ple position was less than 0.2 mm. The first harmonic of the undulator radiation was used for all measurements de-scribed here. It had been confirmed in our previous work that the degree of linear polarization within the first har-monic peak of the undulator radiation is more than 95\% [11]. Two identical ion detectors (channeltrons) with re-tarding grids were installed in the chamber at 0 and 90 relative to the polarization vector of the incident radiation in the plane perpendicular to the radiation path. A re-tarding potential of +3 V was applied to the grid of each detector to select energetic fragment ions only. Each de-tector has a collection half-angle of 10.5 . A parallel plate electrostatic analyzer with a position sensitive detector (a microchannel plate and a resistive anode), which can be rotated around the photon beam axis, was used to energy analyze photoelectrons [11]. The effective acceptance an-gle of the analyzer was estimated to be {\textasciitilde}5 . To obtain coincidence signals between photoelectrons and fragment ions, event signals from the electron detector were fed into two time-to-amplitude cogverters to start them at the same time, and signals from one ion detector were used to stop one of the converters and signals from the other detector to stop the other. As demonstrated in our previous work [11 — 19], the en-ergetic fragment-ion angular distributions after the K-shell excitations of diatomic molecules induced by linearly polarized radiation have enabled us to decompose the conventional photoabsorption spectra into their molecular 0031-9007/95/74(3)/359(4)\$06. 00 1995 The American Physical Society 359},
	number = {3},
	urldate = {2016-11-23},
	journal = {Physical Review Letters},
	author = {Shigemasa, E and Adachi, J and Oura, M and Yagishita, A},
	month = jan,
	year = {1995},
	note = {tex.ids= Shigemasa1995},
	pages = {359--362},
}

The angular distributions of 1so-photoelectrons from N2 molecules held fixed in space have been measured around the or* shape resonance for the first time, The angular distributions have been very rich in structure, which are completely different from usual photoelectron angular distributions from randomly oriented molecules, as predicted by Dill. The orbital angular momentum properties of the 1scr photoelectrons around the o. * shape resonance have been made clear from the angular distribution patterns. PACS numbers: 33.80.Eh, 33.90.+h Molecular K-shell spectra are known to depart remark-ably from corresponding atomic spectra [1]. Specifically, above the K edge there is a broad band of enhanced pho-toabsorption in place of the smooth monotonic decrease one might expect. The novel feature, so called shape res-onance, results from the interaction between the photo-electron escaping from the K shell and the anisotropic molecular field [2]. Direct study of the orbital angular momentum properties of the photoelectrons in the shape resonance is not pos-sible by conventional gas-phase photoelectron angular distribution studies, owing to the random orientations of the molecules. If, however, the molecules have a definite orientation, the angular distributions of photoelectrons ejected by the electric-dipole interaction has the general form [3] 2~max g ~KM' KM(0 tt') @=0 M where the angles (0, tb) are measured from the molecule g axis, I " is the maximum orbital angular momentum component of the outgoing photoelectron, and Y~M are the spherical harmonics. Thus, such photoelectron angular distributions of fixed-in-space molecules can offer a direct probe of the orbital angular momentum composition of the molecular photoelectrons. In the limited case, the angular distribution of photoelectrons from oriented H2 [4], CO [5], and N2 and CO [6] molecules were predicted by three groups. The present experiment has been undertaken to study the orbital angular momentum properties of the photo-electrons in a prototype molecular shape resonance — the o. * shape resonance of nitrogen molecules. In this Let-ter, we present the first experimental results on the an-gular distributions of lsd-photoelectrons ejected from Nz molecules held fixed in space. The photoionization pro-cesses of fixed-in-space molecules in a gas phase can be realized by detecting photoelectrons in coincidence with fragment ions as reported by Golovin et al. [7,8]. Since the dissociation time of the molecular ions produced by a subsequent Auger decay of the K-shell vacancy is much shorter than the molecular rotation period, the emission direction of the fragment ion is considered to be equiva-lent to the molecular orientation at a moment of absorp-tion of a photon. The experiments have been carried out on beam line BL-28, supplying the synchrotron radiation emitted from an undulator [9] inserted in the 2.5 GeV positron stor-age ring at the Photon Factory. The undulator radia-tion, monochromatized with a 10 m grazing incidence monochromator [10], was focused onto an effusive beam of the sample gas at the center of the ionization region of the experimental chamber. The entrance and exit slit openings of the monochromator were both set to 50 p, m. The expected energy resolution was about 0.6 eV at h p = 400 eV. The diameter of the photon beam spot at the sam-ple position was less than 0.2 mm. The first harmonic of the undulator radiation was used for all measurements de-scribed here. It had been confirmed in our previous work that the degree of linear polarization within the first har-monic peak of the undulator radiation is more than 95% [11]. Two identical ion detectors (channeltrons) with re-tarding grids were installed in the chamber at 0 and 90 relative to the polarization vector of the incident radiation in the plane perpendicular to the radiation path. A re-tarding potential of +3 V was applied to the grid of each detector to select energetic fragment ions only. Each de-tector has a collection half-angle of 10.5 . A parallel plate electrostatic analyzer with a position sensitive detector (a microchannel plate and a resistive anode), which can be rotated around the photon beam axis, was used to energy analyze photoelectrons [11]. The effective acceptance an-gle of the analyzer was estimated to be ~5 . To obtain coincidence signals between photoelectrons and fragment ions, event signals from the electron detector were fed into two time-to-amplitude cogverters to start them at the same time, and signals from one ion detector were used to stop one of the converters and signals from the other detector to stop the other. As demonstrated in our previous work [11 — 19], the en-ergetic fragment-ion angular distributions after the K-shell excitations of diatomic molecules induced by linearly polarized radiation have enabled us to decompose the conventional photoabsorption spectra into their molecular 0031-9007/95/74(3)/359(4)$06. 00 1995 The American Physical Society 359

@article{schmidt_photoionization_1992,
	title = {Photoionization of atoms using synchrotron radiation},
	volume = {55},
	issn = {00344885},
	doi = {10.1088/0034-4885/55/9/003},
	abstract = {A comprehensive review is given on photoionization of rare gas atoms using monochromatized synchrotron radiation. Emphasis is put upon the general experimental and theoretical background, and illustrative examples are presented in order to show the present status and the progress in the field during the last decade.},
	number = {9},
	urldate = {2020-01-21},
	journal = {Reports on Progress in Physics},
	author = {Schmidt, V.},
	year = {1992},
	keywords = {\#nosource},
	pages = {1483--1659},
}

A comprehensive review is given on photoionization of rare gas atoms using monochromatized synchrotron radiation. Emphasis is put upon the general experimental and theoretical background, and illustrative examples are presented in order to show the present status and the progress in the field during the last decade.

@article{Manson1982,
	title = {Photoelectron angular distributions: energy dependence for s subshells},
	volume = {54},
	issn = {0034-6861},
	url = {http://rmp.aps.org/abstract/RMP/v54/i2/p389_1},
	doi = {10.1103/RevModPhys.54.389},
	number = {2},
	urldate = {2012-07-19},
	journal = {Reviews of Modern Physics},
	author = {Manson, Steven and Starace, Anthony},
	month = apr,
	year = {1982},
	pages = {389--405},
}

@article{dehmer_shape-resonance-enhanced_1979,
	title = {Shape-resonance-enhanced nuclear-motion effects in molecular photoionization},
	volume = {43},
	issn = {00319007},
	doi = {10.1103/PhysRevLett.43.1005},
	abstract = {Shape resonances in molecular photoionization are shown to induce strong coupling between vibrational and electronic motion over a spectral range several times broader than the resonances half-width. This coupling is manifested by large deviations from Franck-Condon intensity distributions and strong dependence of photoelectron angular distributions on the vibrational state of the residual ion. These effects are illustrated for the 3σg photoionization channel of N2. © 1979 The American Physical Society.},
	number = {14},
	urldate = {2020-01-21},
	journal = {Physical Review Letters},
	author = {Dehmer, J. L. and Dill, Dan and Wallace, Scott},
	year = {1979},
	keywords = {\#nosource},
	pages = {1005--1008},
}

Shape resonances in molecular photoionization are shown to induce strong coupling between vibrational and electronic motion over a spectral range several times broader than the resonances half-width. This coupling is manifested by large deviations from Franck-Condon intensity distributions and strong dependence of photoelectron angular distributions on the vibrational state of the residual ion. These effects are illustrated for the 3σg photoionization channel of N2. © 1979 The American Physical Society.

@article{oh_dependence_1974,
	title = {Dependence of atomic photoeffect on a bound-electron magnetic substate},
	volume = {10},
	issn = {10502947},
	doi = {10.1103/PhysRevA.10.1198},
	abstract = {Flügge, Mehlhorn, and Schmidt have suggested that the dependence of the atomic photoeffect on a bound-electron magnetic substate will have observable consequences for the angular distribution of subsequent Auger electrons. Because of the constraints of parity and time-reversal invariance, this possibility first arises for ejection from LIII and MIII subshells. We have calculated the relative probabilities of {\textbar}jz{\textbar}=32 and {\textbar}jz{\textbar}=12 ejection from these subshells, both with the relativistic Born approximation (Gavrila's formulation) and in the nonrelativistic dipole approximation. The ratio of these cross sections can have a dramatic energy dependence, ranging from 7 at high energies to 9/11 in the low-energy domain, and dropping to 1/3 near threshold if there is a Cooper minimum. Screening effects are discussed. © 1974 The American Physical Society.},
	number = {4},
	urldate = {2020-01-21},
	journal = {Physical Review A},
	author = {Oh, Sung Dahm and Pratt, R. H.},
	year = {1974},
	keywords = {\#nosource},
	pages = {1198--1203},
}

Flügge, Mehlhorn, and Schmidt have suggested that the dependence of the atomic photoeffect on a bound-electron magnetic substate will have observable consequences for the angular distribution of subsequent Auger electrons. Because of the constraints of parity and time-reversal invariance, this possibility first arises for ejection from LIII and MIII subshells. We have calculated the relative probabilities of \textbarjz\textbar=32 and \textbarjz\textbar=12 ejection from these subshells, both with the relativistic Born approximation (Gavrila's formulation) and in the nonrelativistic dipole approximation. The ratio of these cross sections can have a dramatic energy dependence, ranging from 7 at high energies to 9/11 in the low-energy domain, and dropping to 1/3 near threshold if there is a Cooper minimum. Screening effects are discussed. © 1974 The American Physical Society.

@article{carlson_angular_1971,
	title = {Angular distribution of the photoelectron spectra for {Ar}, {Kr}, {Xe}, {H} 2, {N2}, and {CO}},
	volume = {55},
	issn = {00219606},
	doi = {10.1063/1.1675599},
	abstract = {The distribution of photoelectrons as a function of the angle 8 between the direction of the incoming photon and outgoing photoelectron has been measured for Ar, Kr, Xe, Hz, Na, and CO. The experiments have been carried out with a double focusing electrostatic electron spectrometer to which has been attached a chamber containing a gas discharge lamp that can be freely rotated. The Her (584 Å) and Nei (736, 744 Å) resonance lines were used as photon sources. For each of the photoionization bands studied the angular distribution could be fitted to the general shape predicted from theory: 1+β/2 (3/2 sin2θ-1). In addition, the values of the parameter βexperimentally determined were in good agreement with theoretically determined values for Hs and for the rare gases but only partially satisfactory agreement for the first ionization potential of H2. The II states of N2+ and CO+ give lower values of βthan the 2 state according to expectations. In general the vibrational structure for a given band was independent of 9, but several exceptions were found for both N2 and CO, which have been discussed in terms of the presence of autoionization states and possible breakdown in the Born-Oppenheimer approximation.},
	number = {10},
	urldate = {2020-01-21},
	journal = {The Journal of Chemical Physics},
	author = {Carlson, Thomas A. and Jonas, A. E.},
	year = {1971},
	pages = {4913--4924},
}

The distribution of photoelectrons as a function of the angle 8 between the direction of the incoming photon and outgoing photoelectron has been measured for Ar, Kr, Xe, Hz, Na, and CO. The experiments have been carried out with a double focusing electrostatic electron spectrometer to which has been attached a chamber containing a gas discharge lamp that can be freely rotated. The Her (584 Å) and Nei (736, 744 Å) resonance lines were used as photon sources. For each of the photoionization bands studied the angular distribution could be fitted to the general shape predicted from theory: 1+β/2 (3/2 sin2θ-1). In addition, the values of the parameter βexperimentally determined were in good agreement with theoretically determined values for Hs and for the rare gases but only partially satisfactory agreement for the first ionization potential of H2. The II states of N2+ and CO+ give lower values of βthan the 2 state according to expectations. In general the vibrational structure for a given band was independent of 9, but several exceptions were found for both N2 and CO, which have been discussed in terms of the presence of autoionization states and possible breakdown in the Born-Oppenheimer approximation.