Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, 2018 Missouri University of Science and Technology

#### Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, Igor Bray, Don H. Madison, Ian E. Mccarthy

*Don H. Madison*

The coupled-channel optical method solves a set of coupled momentum-space integral equations for a finite set of reaction channels. The remaining channels, including the target continuum, are described by the polarization potential operator, which formally depends on the full three-body state vectors for these channels. The distorted-wave optical potential makes the distorted-wave Born approximation for these state vectors, using exact target states. No other approximation is made. Calculations and comparison with experiment are reported for total ionization cross sections and asymmetries, total excitation cross sections, entrance-channel phenomena, and the coupled 1s,2s,2p channels, at a range of energies.

Correlated Two-Electron Wave Functions Of Any Symmetry, 2018 Missouri University of Science and Technology

#### Correlated Two-Electron Wave Functions Of Any Symmetry, Christopher Bottcher, David R. Schultz, Don H. Madison

*Don H. Madison*

Using a procedure originally due to Hylleraas, a convenient expansion in coupled spherical harmonics which terminates in a very small number of terms is applied to the treatment of fully correlated two-electron wave functions of any symmetry (total angular momentum, parity, and spin). Coupled equations satisfied by these wave functions are derived which are well adapted to computation and which we discretize on a numerical lattice utilizing the basis-spline collocation method. Use of this method which relies on very flexible basis functions is intended to facilitate subsequently the consideration of time-dependent rearrangments such as autoionization, photoionization, and electron-impact excitation and ...

Comparison Of Experiment And Theory For Electron Impact Ionization Of Isoelectronic Atoms And Molecules, 2018 Missouri University of Science and Technology

#### Comparison Of Experiment And Theory For Electron Impact Ionization Of Isoelectronic Atoms And Molecules, Hari Chaluvadi, Kate L. Nixon, Sadek M. Amami, Andrew James Murray, Don H. Madison

*Don H. Madison*

Experimental and Theoretical Triply Differential Cross sections will be presented for low energy electron impact ionization of Ne, CH4, and NH3. The collision mechanisms responsible for the various structures found in the cross sections will be discussed.

Coplanar Asymmetric Angles And Symmetric Energy Sharing Triple Differential Cross Sections For 200 Ev Electron-Impact Ionization Of Ar (3p), 2018 Missouri University of Science and Technology

#### Coplanar Asymmetric Angles And Symmetric Energy Sharing Triple Differential Cross Sections For 200 Ev Electron-Impact Ionization Of Ar (3p), Zehra Nur Ozer, Sadek M. Amami, Onur Varol, Murat Yavuz, Mevlut Dogan, Don H. Madison

*Don H. Madison*

We have measured triple differential cross sections (TDCSs) for electron-impact ionization of the 3p shell of Ar at 200 eV incident electron energy. The experiments have been performed in coplanar asymmetric energy sharing geometry. The experimental results are compared with the theoretical models of three body distorted wave (3DW) and distorted wave Born approximation (DWBA).

Connection Between Superelastic And Inelastic Electron-Atom Collisions Involving Polarized Collision Partners, 2018 Missouri University of Science and Technology

#### Connection Between Superelastic And Inelastic Electron-Atom Collisions Involving Polarized Collision Partners, Klaus Bartschat, Don H. Madison

*Don H. Madison*

It is shown how the results of a recent experiment by Jiang, Zuo, Vuković, and Bederson [Phys. Rev. Lett. 68, 915 (1992)], who investigated low-energy electron scattering from laser-excited polarized sodium atoms in the initial (3p) 2P°3/2 (F=3, MF=3) state, can be related to the inelastic 3S→3P transition involving initially unpolarized electron and atom beams. Hence, this method can provide an independent check of the traditional electron-scattering experiment with unpolarized beams.

Comparison Of Experimental And Theoretical Electron Ejection Cross Sections In Helium By Proton Impact From 5 To 100 Kev, 2018 Missouri University of Science and Technology

#### Comparison Of Experimental And Theoretical Electron Ejection Cross Sections In Helium By Proton Impact From 5 To 100 Kev, M. Eugene Rudd, Don H. Madison

*Don H. Madison*

Absolute values of doubly differential cross sections are obtained for electron production in helium by 5- to 100-keV proton impact. The measured values along with earlier data at higher energies are compared with theoretical plane-wave Born-approximation functions obtained from a Hartree-Fock potential. Not only is good agreement obtained at high impact energies (above 300 keV), but fairly good agreement is found at low energies (below about 20 keV). For electrons ejected in the backward hemisphere, unexpectedly poor agreement is noted at intermediate energies where the measured cross sections dip to 50% of the calculated values in some cases. Singly differential ...

Comment On "Role Of The Ground State In Electron-Atom Double Ionization" [1] (Multiple Letters), 2018 Missouri University of Science and Technology

#### Comment On "Role Of The Ground State In Electron-Atom Double Ionization" [1] (Multiple Letters), Jamal Berakdar, Stephenie J. Jones, Don H. Madison

*Don H. Madison*

No abstract provided.

Comparison Of Electron-Atom Collision Parameters For S To P Transitions Under Reversal Of Energy Transfer, 2018 Missouri University of Science and Technology

#### Comparison Of Electron-Atom Collision Parameters For S To P Transitions Under Reversal Of Energy Transfer, Max Shurgalin, Andrew James Murray, William R. Macgillivray, M. C. Standage, Don H. Madison, Kathrin D. Winkler, Igor Bray

*Don H. Madison*

Inelastic and superelastic electron scattering from the optically prepared 32P3/2 state of sodium has enabled atomic collision parameters to be deduced for the 4S-3P deexcitation and the 3S-3P excitation processes. These data are compared with convergent close coupling and second order distorted wave Born calculations. For excitation, both theories agree with experiment, whereas for deexcitation the close coupling theory is in better agreement. A long-standing proposal relating to the sign of the transferred angular momentum is not supported.

Coincidence Angular Correlation In Electron Impact Single Or Double Ionisation Of Atoms And Molecules, 2018 Missouri University of Science and Technology

#### Coincidence Angular Correlation In Electron Impact Single Or Double Ionisation Of Atoms And Molecules, E. M. Staicu-Casagrande, Adnan Naja, Xueguang Ren, Mohammed Nekkab, Fabrice Catoire, F. Mezdari, Azzeddine Lahmam-Bennani, Don H. Madison, Ochbadrakh Chuluunbaatar, Boghos B. Joulakian

*Don H. Madison*

Experimental results obtained with our multi-parameter multi-coincidence spectrometer are presented for the (e,3e) double ionisation of Ar and (e,2e) single ionisation of small molecules. The (e,3e) measurements are discussed in terms of competition between the two double ionisation processes present under the chosen kinematics, and qualitative conclusions are given. The results for the ionisation of H_{2} and the outer orbital of N_{2} are compared with the predictions of the most elaborate available theoretical models for description of the molecular ionisation process. Overall reasonable agreement is observed and tentative interpretations for the discrepancies are discussed.

(E,2e) Study Of Two-Center Interference Effects In The Ionization Of N2, 2018 Missouri University of Science and Technology

#### (E,2e) Study Of Two-Center Interference Effects In The Ionization Of N2, Leigh R. Hargreaves, Christopher J. Colyer, Mark A. Stevenson, B. Lohmann, Ola A. Al-Hagan, Don H. Madison, Chuangang Ning

*Don H. Madison*

A number of previous studies have suggested the possibility of two-center interference effects in the single ionization of diatomic molecules such as H_{2} and N_{2}. While interference effects have been successfully observed in the ionization of H_{2}, to date evidence for interference in N_{2} ionization has yet to be conclusively demonstrated. This study presents triply differential cross sections for electron impact ionization of N_{2}, measured using the (e,2e) technique. The data are probed for signatures of two-center interference effects. Evidence for interference manifesting in the cross sections is observed.

Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, 2018 Missouri University of Science and Technology

#### Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, Jingbo Wang, J. F. Williams, Andris T. Stelbovics, John E. Furst, Don H. Madison

*Don H. Madison*

In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed 1s4f state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the 1s4f state.

A Dynamical (E,2e) Investigation Of The Structurally Related Cyclic Ethers Tetrahydrofuran, Tetrahydropyran, And 1,4-Dioxane, 2018 Missouri University of Science and Technology

#### A Dynamical (E,2e) Investigation Of The Structurally Related Cyclic Ethers Tetrahydrofuran, Tetrahydropyran, And 1,4-Dioxane, J. D. Builth-Williams, Susan M. Bellm, Luca Chiari, Penny A. Thorn, Darryl B. Jones, Hari Chaluvadi, Don H. Madison, Chuangang Ning, B. Lohmann, Gabriel Da Silva, Michael J. Brunger

*Don H. Madison*

Triple differential cross section measurements for the electron-impact ionization of the highest occupied molecular orbitals of tetrahydropyran and 1,4-dioxane are presented. For each molecule, experimental measurements were performed using the (e,2e) technique in asymmetric coplanar kinematics with an incident electron energy of 250 eV and an ejected electron energy of 20 eV. With the scattered electrons being detected at -5°, the angular distributions of the ejected electrons in the binary and recoil regions were observed. These measurements are compared with calculations performed within the molecular 3-body distorted wave model. Here, reasonable agreement was observed between the theoretical model ...

(E,2e) Measurements On Xenon: Reexamination Of The Fine-Structure Effect, 2018 Missouri University of Science and Technology

#### (E,2e) Measurements On Xenon: Reexamination Of The Fine-Structure Effect, Radmila Panajotovic, Julian C A Lower, Erich Weigold, A. Prideaux, Don H. Madison

*Don H. Madison*

The process of electron scattering from heavy target atoms is of considerable interest due to the enhanced role of relativistic effects and distortion of the electron trajectories resulting from the large value of nuclear charge. Here we present (e,2e) ionization measurements and distorted-wave Born approximation calculations for the scattering of spin-polarized electrons from xenon atoms in which the fine-structure levels of the residual ion are resolved. Comparison of measurements performed using a high-sensitivity toroidal analyzer spectrometer with the predictions of sophisticated calculations provide an improved understanding of the ionization dynamics of heavy target atoms and the treatment of electron ...

Using Geometry To Manipulate Long-Range Correlation Of Light Inside Disordered Media, 2018 Missouri University of Science and Technology

#### Using Geometry To Manipulate Long-Range Correlation Of Light Inside Disordered Media, Raktim Sarma, Alexey Yamilov, Pauf Neupane, Hui Cao

*Alexey Yamilov*

We demonstrate an effective approach of modifying the long-range spatial correlation for light propagating inside random photonic waveguides by varying the shape of the waveguide. The functional form of spatial correlation is no longer universal in the regime of diffusive transport and becomes shape dependent due to the nonlocal nature of wave propagation. The spatial dependence of the correlation may become asymmetric for light incident from opposite ends of the waveguide. This work opens the door to control nonlocal effects in mesoscopic transport of waves by tailoring the geometry of random systems. .

Relation Between Transmission And Energy Stored In Random Media With Gain, 2018 Missouri University of Science and Technology

#### Relation Between Transmission And Energy Stored In Random Media With Gain, Ben Payne, Jonathan Andreasen, Hui Cao, Alexey Yamilov

*Alexey Yamilov*

In this work, we investigate a possibility of using the ratio between optical transmission, T, and energy stored inside the system, E, as a quantitative measure of the enhanced mesoscopic corrections to diffusive transport of light through a random medium with gain. We obtain an expression for T/E as a function of amplification strength in the diffusive approximation and show that it does not a have tendency to diverge when the threshold for random lasing is approached, as both T and E do. Furthermore, we find that a change in T/E signifies a change in the electric field ...

Statistics Of Transmission In One-Dimensional Disordered Systems: Universal Characteristics Of States In The Fluctuation Tails, 2018 Missouri University of Science and Technology

#### Statistics Of Transmission In One-Dimensional Disordered Systems: Universal Characteristics Of States In The Fluctuation Tails, Lev I. Deych, Mikhail V. Erementchouk, Alexander A. Lisyansky, Alexey Yamilov, Hui Cao

*Alexey Yamilov*

We numerically study the distribution function of the conductance (transmission) in the one-dimensional tight-binding Anderson and periodic-on-average superlattice models in the region of fluctuation states where single parameter scaling is not valid. We show that the scaling properties of the distribution function depend upon the relation between the system's length L and the length l_{s} determined by the integral density of states. For long enough systems, L ≫ l_{s}, the distribution can still be described within a new scaling approach based upon the ratio of the localization length l_{loc} and l_{s}. In an intermediate interval of ...

Shape Dependence Of Transmission, Reflection, And Absorption Eigenvalue Densities In Disordered Waveguides With Dissipation, 2018 Missouri University of Science and Technology

#### Shape Dependence Of Transmission, Reflection, And Absorption Eigenvalue Densities In Disordered Waveguides With Dissipation, Alexey Yamilov, Sasha Petrenko, Raktim Sarma, Hui Cao

*Alexey Yamilov*

The universal bimodal distribution of transmission eigenvalues in lossless diffusive systems underpins such celebrated phenomena as universal conductance fluctuations, quantum shot noise in condensed matter physics, and enhanced transmission in optics and acoustics. Here, we show that in the presence of absorption, the density of the transmission eigenvalues depends on the confinement geometry of the scattering media. Furthermore, in an asymmetric waveguide, the densities of the reflection and absorption eigenvalues also depend on the side from which the waves are incident. With increasing absorption, the density of absorption eigenvalues transforms from a single-peak to a double-peak function. Our findings open ...

Tunable Local Polariton Modes In Semiconductors, 2018 Missouri University of Science and Technology

#### Tunable Local Polariton Modes In Semiconductors, Michael G. Foygel, Alexey Yamilov, Lev I. Deych, Alexander A. Lisyansky

*Alexey Yamilov*

We study the local states within the polariton band gap that arise due to deep defect centers with strong electron-phonon coupling. Electron transitions involving deep levels may result in alteration of local elastic constants. In this case, substantial reversible transformations of the impurity polariton density of states occur, which include the appearance/disappearance of the polariton impurity band, and its shift and/or the modification of its shape. These changes can be induced by thermo- and photoexcitation of the localized electron states or by trapping of injected charge carriers. We develop a simple model, which is applied to the Op ...

Scaling In One-Dimensional Localized Absorbing Systems, 2018 Missouri University of Science and Technology

#### Scaling In One-Dimensional Localized Absorbing Systems, Lev I. Deych, Alexey Yamilov, Alexander A. Lisyansky

*Alexey Yamilov*

Numerical study of the scaling of transmission fluctuations in the one-dimensional localization problem in the presence of absorption is carried out. Violations of single-parameter scaling for lossy systems are found and explained on the basis of a new criterion for different types of scaling behavior derived by Deych et al.

Probing Long-Range Intensity Correlations Inside Disordered Photonic Nanostructures, 2018 Missouri University of Science and Technology

#### Probing Long-Range Intensity Correlations Inside Disordered Photonic Nanostructures, Raktim Sarma, Alexey Yamilov, Pauf Neupane, Boris Shapiro, Hui Cao

*Alexey Yamilov*

We report the direct observation of the development of long-range spatial intensity correlation and the growth of intensity fluctuations inside random media. We fabricated quasi-two-dimensional disordered photonic structures and probed light transport from a third dimension. Good agreement between experiment and theory is obtained. We were able to manipulate the long-range intensity correlation and intensity fluctuations inside the disordered waveguides by simply varying the waveguide geometry.