Calculation of density of states for modeling photoemission using method of moments

Daniel Finkenstadt; Samuel G. Lambrakos; Kevin L. Jensen; Andrew Shabaev; Nathan A. Moody

doi:10.1117/12.2272749

6 September 2017 Calculation of density of states for modeling photoemission using method of moments

Daniel Finkenstadt, Samuel G. Lambrakos, Kevin L. Jensen, Andrew Shabaev, Nathan A. Moody

Proceedings Volume 10374, Optical Modeling and Performance Predictions IX; 103740F (2017) https://doi.org/10.1117/12.2272749
Event: SPIE Optical Engineering + Applications, 2017, San Diego, California, United States

Abstract

Modeling photoemission using the Moments Approach (akin to Spicer’s “Three Step Model”) is often presumed to follow simple models for the prediction of two critical properties of photocathodes: the yield or “Quantum Efficiency” (QE), and the intrinsic spreading of the beam or “emittance” ε_n;rms. The simple models, however, tend to obscure properties of electrons in materials, the understanding of which is necessary for a proper prediction of a semiconductor or metal’s QE and ε_n;rms. This structure is characterized by localized resonance features as well as a universal trend at high energy. Presented in this study is a prototype analysis concerning the density of states (DOS) factor D(E) for Copper in bulk to replace the simple three-dimensional form of D(E) = (m/π² h³)p2mE currently used in the Moments approach. This analysis demonstrates that excited state spectra of atoms, molecules and solids based on density-functional theory can be adapted as useful information for practical applications, as well as providing theoretical interpretation of density-of-states structure, e.g., qualitatively good descriptions of optical transitions in matter, in addition to DFT’s utility in providing the optical constants and material parameters also required in the Moments Approach.

Citation Download Citation

Daniel Finkenstadt, Samuel G. Lambrakos, Kevin L. Jensen, Andrew Shabaev, and Nathan A. Moody "Calculation of density of states for modeling photoemission using method of moments", Proc. SPIE 10374, Optical Modeling and Performance Predictions IX, 103740F (6 September 2017); https://doi.org/10.1117/12.2272749

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