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Full-Text Articles in Physical Sciences and Mathematics

Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley Aug 2010

Frequency Dependence In The Initiation Of Laser-Induced Damage, Jeremy Gulley

Jeremy R. Gulley

Numerous studies have investigated the role of photoionization in ultrafast laser-induced damage of bulk dielectrics. This study examines the role of spectral width and instantaneous laser frequency in laser-induced damage using a frequency dependent multiphoton ionization model and numerical simulation of an 800 nm laser pulse propagating through fused silica. When the individual photon wavelengths are greater than 827 nm, an additional photon is required for photoionization, reducing the probability of the event by many orders of magnitude. Simulation results suggest that this frequency dependence may significantly affect the processes of laser-induced damage and filamentation.


Fivefold Differential Cross Sections For Ground-State Ionization Of Aligned H₂ By Electron Impact, Arne Senftleben, Ola A. Al-Hagan, Thomas Pfluger, Xueguang Ren, Don H. Madison, Alexander Dorn, Joachim Hermann Ullrich Jul 2010

Fivefold Differential Cross Sections For Ground-State Ionization Of Aligned H₂ By Electron Impact, Arne Senftleben, Ola A. Al-Hagan, Thomas Pfluger, Xueguang Ren, Don H. Madison, Alexander Dorn, Joachim Hermann Ullrich

Physics Faculty Research & Creative Works

We discuss the ionization of aligned hydrogen molecules into their ionic ground state by 200 eV electrons. Using a reaction microscope, the complete electron scattering kinematics is imaged over a large solid angle. Simultaneously, the molecular alignment is derived from postcollision dissociation of the residual ion. It is found that the ionization cross section is maximized for small angles between the internuclear axis and the momentum transfer. Fivefold differential cross sections (5DCSs) reveal subtle differences in the scattering process for the distinct alignments. We compare our observations with theoretical 5DCSs obtained with an adapted molecular three-body distorted wave model that ...


Comment On "Coincidence Studies Of He Ionized By C⁶⁺, Au²⁴⁺, And Au⁵³⁺", Michael Schulz, Robert Moshammer, Daniel Fischer, Joachim Hermann Ullrich Jun 2010

Comment On "Coincidence Studies Of He Ionized By C⁶⁺, Au²⁴⁺, And Au⁵³⁺", Michael Schulz, Robert Moshammer, Daniel Fischer, Joachim Hermann Ullrich

Physics Faculty Research & Creative Works

In a recent article, McGovern [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA. 81.042704 81, 042704 (2010)] suggested that the normalization of our measured fully differential cross section for ionization of helium by Au53+ needs to be checked. In this comment we confirm that the normalization of the published data is correct. Furthermore, we point out that, for a conclusive comparison between experiment and theory, an accurate inclusion of the experimental resolution using correct experimental parameters in the calculation is important.


Determination Of Structure Parameters In Strong-Field Tunneling Ionization Theory Of Molecules, Song-Feng Zhao, Cheng Jin, Anh-Thu Le, T. F. Jiang, C. D. Lin Mar 2010

Determination Of Structure Parameters In Strong-Field Tunneling Ionization Theory Of Molecules, Song-Feng Zhao, Cheng Jin, Anh-Thu Le, T. F. Jiang, C. D. Lin

Physics Faculty Research & Creative Works

In the strong field molecular tunneling ionization theory of Tong et al. [Phys. Rev. A 66, 033402 (2002)], the ionization rate depends on the asymptotic wave function of the molecular orbital from which the electron is removed. The orbital wave functions obtained from standard quantum chemistry packages in general are not good enough in the asymptotic region. Here we construct a one-electron model potential for several linear molecules using density functional theory. We show that the asymptotic wave function can be improved with an iteration method and after one iteration accurate asymptotic wave functions and structure parameters are determined. With ...