Thomas P. Debies

Bio: Thomas P. Debies is an academic researcher from University of Houston. The author has contributed to research in topics: Photoionization & Ionization energy. The author has an hindex of 4, co-authored 5 publications receiving 208 citations.

Calculated photoionization cross sections and relative experimental photoionization intensities for a selection of small molecules

Abstract: The general equations for calculating photoionization cross sections of polyatomic molecules in the plane‐wave and orthogonalized plane‐wave approximations have been programmed for the electronic computer. Applications are described for the molecules H2, CH4, N2, CO, H2O, H2S, and H2CCH2 for incident photon energies from threshold to 1500 eV. Relative experimental photoionization band intensities for the above molecules are measured using NeI, HeI, and HeII resonance radiation. A simplified analysis of the intensities derived from electrostatic deflection analyzers is presented. The 2P3/2:2P1/2 intensity ratios of the rare gases are determined with the three modes of excitation mentioned above. An analysis of the resolution capabilities of an electrostatic deflection spectrometer as a function of electron kinetic energy is presented. Relative experimental photoionization band intensities for the above molecules obtained by ionization with the three uv sources and MgKa and A1Ka x‐ray sources are compared with computed differential cross sections. Variations in computed cross sections as a function of the kinetic energy of the photoelectrons are discussed and possible interpretations are proposed.

Erratum: Calculated angular distributions of photoelectrons using the orthogonalized plane‐wave approximation

Abstract: The general equations for calculating angular distributions of photoelectrons within the orthogonalized plane‐wave approximation have been programmed for the electronic computer. Applications are described for the molecules CH4, H2O, and N2 with incident photon energies from threshold to 1254 eV. Computed values of the asymmetry parameter β are compared to experimentally determined β values using HeI excitation. Large variations in β as a function of photon energy are obtained; possible interpretations are proposed.

Attosecond Electron Dynamics in Molecules.

Abstract: Advances in attosecond science have led to a wealth of important discoveries in atomic, molecular, and solid-state physics and are progressively directing their footsteps toward problems of chemical interest. Relevant technical achievements in the generation and application of extreme-ultraviolet subfemtosecond pulses, the introduction of experimental techniques able to follow in time the electron dynamics in quantum systems, and the development of sophisticated theoretical methods for the interpretation of the outcomes of such experiments have raised a continuous growing interest in attosecond phenomena, as demonstrated by the vast literature on the subject. In this review, after introducing the physical mechanisms at the basis of attosecond pulse generation and attosecond technology and describing the theoretical tools that complement experimental research in this field, we will concentrate on the application of attosecond methods to the investigation of ultrafast processes in molecules, with emphasis i...

Molecular Electron Propagator Theory and Calculations

Abstract: Publisher Summary This chapter describes that the electron propagator is being employed in molecular theory primarily for the calculation of electron binding energies as well as for photoionization cross sections and intensities related to various spectrometric processes. The usefulness of propagator theory is by no means limited to the realm of electron binding energies. All areas of spectrometry can be given a unified treatment and the solution of the equation of motion for the appropriate propagator yields a spectral density function and energy differences from which expectation values and spectra can be obtained. The chapter reviews some of the basic definitions and introduces the notations of the electron propagator. The decoupling problem is stated and general methods of approximation are discussed using a spin orbital basis. The direct pole-residue search is described and implemented. It is discussed for the solution of the working equations to produce the spectral representation of the electron propagator. The emphasis is placed on the calculation of relative intensities of lines in photoelectron spectra.