Atomic harmonic generation in time-dependent R-matrix theory

Abstract

We have developed the capability to determine accurate harmonic spectra for multielectron atoms within time-dependent R-matrix (TDRM) theory. Harmonic spectra can be calculated using the expectation value of the dipole length, velocity or acceleration operator. We assess the calculation of the harmonic spectrum from He irradiated by 390 nm laser light with intensities up to 4 x 10(14) W cm(-2) using each form, including the influence of the multielectron basis used in the TDRM code. The spectra are consistent between the different forms, although the dipole acceleration calculation breaks down at lower harmonics. The results obtained from TDRM theory are compared with results from the HELIUM code finding good quantitative agreement between the methods. We find that bases which include pseudostates give the best comparison with the HELIUM code, but models comprising only physical orbitals also produce accurate results.

9 pages, 7 figures

References in corpus (5)

• Bright quasi-phasematched soft x-ray harmonic radiation from Argon ions
• High-order Harmonic Spectroscopy of the Cooper Minimum in Argon: Experimental and Theoretical Study
• Time delay between photoemission from the 2p and 2s subshells of Neon
• The Impact of Multichannel and Multipole Effects on the Cooper Minimum in the High-Harmonics Spectrum of Argon
• Interference between competing pathways in harmonic generation

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• Harmonic generation of noble-gas atoms in the Near-IR regime using ab-initio time-dependent R-matrix theory
• Pulse-shape control of two-color interference in high-order-harmonic generation
• Spin-Orbit Effects in Atomic High-Harmonic Generation
• Extreme-ultraviolet-initiated High-harmonic Generation in Ar${}^{+}$
• The influence of multiple ionization thresholds on harmonic generation: Ar+
• On the Cooper Minimum in Singly ionized and Neutral Argon
• Multichannel Interference In High-Order Harmonic Generation From Ne(+) Driven By Ultrashort Intense Laser Pulse
• Enhanced Harmonic Generation from M=1 aligned Ar+
• High-Harmonic Generation in the Water Window from mid-IR Laser Sources