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Journal of Physics B: Atomic, Molecular and Optical Physics - latest papers

Latest articles for Journal of Physics B: Atomic, Molecular and Optical Physics

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  • Orientational anisotropy of photoemitting CS2 molecules induced by molecular field splitting
    We recorded the sulfur 2p photoelectron spectrum from gas-phase CS2 molecules, in coincidence with the ionic fragments S+, S2+ and CS+. The fragments are created by the dissociation of the parent molecular dication following the Auger decay of the S 2p vacancy. The S 2p photoelectrons were recorded in the direction of the polarization vector of synchrotron radiation at FinEstBeAMS beamline of MAX IV synchrotron, using a hemispherical energy analyzer with sufficiently high resolution to resolve the molecular field splitting effects. The coincident ionic fragments of the linear molecule provided the orientation of the molecular axis of molecules emitting electrons in the polarization direction along the polarization vector of the incident photon beam and we obtained the orientation distributions of these molecules for photoemission from the three spin–orbit and molecular field split components in the S 2p orbital. The molecular field splitting introduced clear differences in the measured orientation distributions. Photoemission along the polarization vector from the 2p orbital with created the most isotropic distribution of the emitter molecules, while the distribution corresponding to the 2p orbital with was preferredly perpendicular to the polarization vector. Emission from the 2p orbital with came from molecules preferably oriented along the polarization vector. We compare these results to previous theoretical predictions with a good quantitative agreement for the components with . However, the measured anisotropy for the components with is somewhat weaker than predicted. This work demonstrates how the electron-ion coincidence technique allows, with high electron energy resolution, for testing photoelectron angular distribution predictions, with the constraint that the polarization vector of the incident photons is parallel to the momentum vector of the photoelectron.

  • A mathematical formalism for computing cross sections for the single ionization of atoms and simple molecules by fast proton impact: application to the H ...
    In this paper, we present an analytical formalism for computing triple and fourfold differential cross sections for the single ionization by proton impact of atoms as well as oriented and randomly oriented molecules. To improve the accuracy of the standard one Coulomb wave model, we incorporate the Salin factor, which provides a better approximation for the electron’s transition to the continuum. Although demonstrated for proton impact, the formalism is generalizable to other light ions. Its mathematical structure is designed to be both simple and practical, facilitating straightforward implementation and high computational efficiency, making it ideal for large-scale simulations. We validate the formalism by comparing the double differential cross sections for the ionization of water molecules with existing experimental data, demonstrating close agreement.

  • Unveiling quantum features of time-dependent electron spins influenced by Zeeman energy and symmetric cross spin
    This paper investigates quantum correlations between two identical spin-1/2 particles linked by long-range dipolar interactions. A time-dependent symmetric cross-spin interaction and an external homogeneous magnetic field that varies with time are also applied to the system. Quantum correlations, such as entanglement, steering, and steered quantum coherence, are quantified using concurrence, three-steering functions, and the l1 norm measure of coherence, respectively. These quantum correlations are examined based on the direction of interaction for dipole–dipole interactions along either the x-axis or z-axis and are symmetric concerning Zeeman energy along these axes. The maximal bounds of all three quantifiers are obtained by increasing the frequency of the time-dependent and symmetric coupling parameters. These maximal bounds significantly strengthen when considering symmetric and Zeeman interactions along the x-axis; however, the pinnacle of entanglement is reached in perpendicular configurations.

  • Photoluminescence of L-cystine and taurine molecules
    This paper describes the measurement techniques and results obtained by optical spectroscopy under photon excitation of aliphatic sulfur-containing amino acid molecules in a microcrystalline state (powder). The photoluminescence (PL) spectra of L-cystine and taurine were investigated for the first time in the 400–700 nm wavelength range upon excitation by photons with energies of 3.26–4.51 eV. The measured PL spectra revealed emission from CH radicals. The PL spectra of taurine also exhibited emission from the hydroxyl radical OH. The dependence of the PL spectra (structure, emission intensity, peak positions) on the excitation photon energy was studied. It was shown that the presence of a disulfide bond in the L-cystine molecule has a decisive influence on the formation of its PL spectrum.

  • Interaction time of two macroscopic quantum wave packets colliding with a rectangular barrier
    We theoretically study the dynamical process of two macroscopic quantum wave packets colliding with a rectangular barrier. We define an interaction time as the time interval between two instants when the atomic probability reaches its maximum at the center and edges of the barrier, serving as a key quantity to characterize this collision process. The impacts of various barrier parameters and wave packet incident energies on the interaction time are systematically explored. Two interferometry schemes, namely Mach–Zehnder scheme and Hong–Ou–Mandel (HOM) scheme, are proposed to determine the interaction time, and the mappings between the interaction time and the observable quantities of the two schemes are established. Through a comparative analysis of the sensitivity of the observable quantities, it is revealed that the HOM scheme exhibits distinct advantages. This research contributes to the quantitative study of quantum tunneling and matter-wave interference, and it is anticipated that the findings can be experimentally validated.