Related papers: The influence of multiple ionization thresholds on…
We investigate harmonic generation (HG) from ground-state Ar+ aligned with M=1 at a laser wavelength of 390-nm and intensity of 4x10(14) Wcm-2. Using time-dependent R-matrix theory, we find that an initial state with magnetic quantum number…
We apply the time-dependent R-matrix method to investigate harmonic generation from Ne(+) at a wavelength of 390 nm and intensities up to 10(15) Wcm(-2). The 1s(2)2s(2)2p(4) (3)P(e), (1)D(e), and (1)S(e) states of Ne(2+) are included as…
We investigate the influence of the autoionizing 3s3p(6)nl resonances on the fifth harmonic generated by 200 - 240 nm laser fields interacting with Ar. To determine the influence of a multi-electron response we have developed capability…
High-order harmonic generation in multiphoton ionization regime is studied theoretically to examine the resonant effects of the generating particle. We solve the time-dependent Schr\"odinger equation for In+ in the laser field by expanding…
We employ the R-matrix with time-dependence method to investigate extreme-ultraviolet-initiated high-harmonic generation (XIHHG) in Ar$^{+}$. Using a combination of extreme-ultraviolet (XUV, $92\textrm{ nm}$, $3\times…
We report on calculations of harmonic generation by neon in a mixed (800-nm + time-delayed 400-nm) laser pulse scheme. In contrast with previous studies we employ a short (few-cycle) 400-nm pulse, finding that this affords control of the…
The below-threshold harmonic generation in the multiphoton ionization regime for a helium atom driven by the elliptically polarized laser field is studied numerically within the framework of two-dimensional (2D) and three-dimensional (3D)…
High-order harmonic generation is investigated for H$_2^+$ and D$_2^+$ with and without Born-Oppenheimer approximation by numerical solution of full dimensional electronic time-dependent Schr\"{o}dinger equation under 4-cycle intense laser…
An interesting property of high harmonic generation in solids is its laser polarization dependent nature which in turn provides information about the crystal and band structure of the generation medium. Here we report on the linear…
The high harmonic generation from atoms in the combination of chirped laser pulse and static field is theoretically investigated. For the first time, we explore a further physical mechanism of the significant extension of high harmonic…
The emission of above-ionization-threshold harmonics results from the recombination of two electron wavepackets moving along a "short" and a "long" trajectory in the atomic continuum. Attosecond pulse train generation has so far been…
High-order harmonic generation (HHG) from molecular ion HeH$^{2+}$ in two initial states of $1s\sigma$ (ground state) and $2p\sigma$ (first excited state) is investigated theoretically, in homogeneous and plasmonic-enhanced laser fields.…
We present studies of high-order harmonic generation (HHG) at laser intensities well above saturation. We use driving laser pulses which present a particular electron dynamics in the turn-on stage. Our results predict an increasing on the…
Fully quantum treatment explicitly presents the high harmonic generation as a three-stage process: above threshold ionization (ATI) is followed by the continuum electron propagation in a laser field and subsequent stimulated recombination…
We study high-order harmonic generation in aligned molecules close to the ionization threshold. Two distinct contributions to the harmonic signal are observed, which show very different responses to molecular alignment and ellipticity of…
We establish how the intensities of the higher harmonics that arise when a photoelectron recombines with a parent ion depend functionally on the parameters of the laser wave and atomic medium, and estimate the limiting values of these…
When molecules interact with intense light sources of femtosecond or shorter duration the rotational degrees of freedom are frozen during the response to the strong nonperturbative interaction. We show how the frozen degrees of freedom…
In present paper we develop an analytic theory for the harmonic generation of symmetric diatomic molecular ions beyond two-level model, emphasizing the influence of charge-resonance (CR) states those are strongly coupled to electromagnetic…
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…
We present ab initio calculations using the $R$-matrix with time dependence (RMT) method for high-order harmonic generation (HHG) in argon in a short, intense pulse regime. The calculations employ a $6$-cycle $\sin^2$ pulse at $850$ nm with…