Lue-Yung Chow Chiu

Bio: Lue-Yung Chow Chiu is an academic researcher from Goddard Space Flight Center. The author has contributed to research in topics: Electron & Spin polarization. The author has an hindex of 2, co-authored 2 publications receiving 7 citations.

Forbidden photo-ionization and electron spin polarization.

Abstract: Photoionization by spin-dependent electric dipole and spin-dependent magnetic quadrupole transitions with polarized electron spin

Spin magnetic effect on the polarization of the electron-atom impact radiation.

Abstract: Spin magnetic effect on polarization of electron- atom impact radiation at threshold energy, calculating various transitions for helium atom

Optical detection of electron polarization

Abstract: A method is suggested for measuring the polarization of low-energy electron beams by observing the polarization of the light emitted by mercury atoms following their excitation by electron impact. It is shown that the asymmetry of the left and right circularly polarized components of the 2537 Angstrom radiation of the even isotopes is approximately equal to the longitudinal polarization of the incident electron beam. The efficiency of such a detector is estimated for incident electron energies near the excitation threshold and its expected performance compares favourably with that of a typical Mott detector. Some distinctive advantages of the proposed scheme are pointed out.

Relativistic Effect and Nonconservative Spin–Orbital Forces in the Radiative Transition of Molecules

Abstract: A treatment is given of a one‐electron orbital model for a many‐electron molecule, in which each electron is allowed to interact with the over‐all orbital and spin magnetic fields, as well as the (Coulomb) electric field of the rest of the electrons and nuclei. It is shown that when redundancy is properly taken care of, by introducing a factor of 12 for the mutual‐magnetic vector potential Aij between the electrons, the subsequent reduction of Dirac's equation reproduces all of Darwin's orbit–orbit, spin–own‐orbit, spin–other‐orbit, and spin–spin interactions, etc., given by the Breit–Pauli approximation. The above treatment is extended to a system of Dirac electrons interacting with the (time‐dependent) electromagnetic field of radiation, in which field–field interaction in the form of Aij·Aj (radiation), is also included. After integration over the photon space, effective transition operators for the large‐component spinors are obtained. When the non‐Hermitian part of the “Dirac Hamiltonian” for the lar...

Photoionization and photoelectron angular distribution for H2

Abstract: Photoionization of H2(1Σg+) in a vibrational υ″ and rotational N″ state into H2+(2Σg+) in a vibrational υ′ and rotational N′ state is studied theoretically. The differential cross section, after summing over the final states, is expressed in the well-known simple form of ( σ T 4π )[1 + βP 2 ( cos θ)] . Parallel expressions are obtained for H2+ in a specific υ′ state (in terms of σ(υ′) and β(υ′)) and for H2+ in a rotational fine level υ′N′ (in terms of σ(υ′N′) and β(υ′N′)). Asymmetry parameters β, β(υ′) and β υ′N′), which are expressed in terms of Racah and Clebsch-Gordan coefficients and electronic transition moments, can be reduced approximately to 2 lineary polarized light and to -1 for unpolarized light. Using single-center electronic wave functions and including partial eaves l = 1, 3, and 5, σ(υ′) and β(υ′) are computed as a function of υ′ at 584 A. The computed σ(υ′) divided by the Frank-Condon overlap, in agreement with experimental results, increases monotonically with υ′; σT and β are computed in the incident photon energy range of 600–4000 A and the results compare favorably with previous calculations.

Depolarization of Resonance Fluorescence from Interacting Atoms

Abstract: The polarization of the resonance fluorescence of interacting atoms and the transfer of coherence, due to the exchange of excitation, are studied theoretically. The treatment is for the general case where both the excited and the ground states can have arbitrary angular momenta, except that they can be connected to each other by an allowed transition. Electrostatic dipole–dipole interaction and electromagnetic radiative interaction are considered simultaneously as the perturbations on the system. Heitler and Ma's generalized time‐dependent perturbation method is used. The system is quantized with respect to the space‐fixed z axis and a static magnetic field along the z axis may be present, so that the magnetic sublevels (m, m′, etc., for the excited state J, and α, β, etc., for the ground state J′) are not necessarily degenerate. The intensity of the scattered light of a given polarization, in a given direction, is expressed as a function of kR (where ℏck is the energy of excitation and R is the internucl...