Dmitry Telnov
Department of Physics, St. Petersburg State University, St. Petersburg, Russia
13 shared publications
Shih-I Chu
Center for Quantum Science and Engineering, Department of Physics, National Taiwan University, Taipei 10617, Taiwan
12 shared publications
Shih-I Chu
Department of Physics, Center for Quantum Science and Engineering and Center for Advanced Study in Theoretical Sciences, National Taiwan University, Taipei 10617, Taiwan
5 shared publications
Eric Cunningham
SLAC National Accelerator Laboratory
2 shared publications
He Wang
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
2 shared publications
Michael Chini
The Ohio State University
2 shared publications

Latest Publications

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Cited by 21
- 17 September 2018
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
Multiphoton Ionization of One-Electron Relativistic Diatomic Quasimolecules in Strong Laser Fields
by Dmitry A. Telnov, Dmitry A. Krapivin, John Heslar, Shih-I Chu
We perform a theoretical and computational study of relativistic one-electron homonuclear diatomic quasimolecules subject to strong electromagnetic fields linearly polarized along the molecular axis. Several quasimolecules with the nuclear charges 1–92 and appropriately scaled internuclear distances and field parameters are used in the calculations. The time-dependent Dirac equation is solved with the help of the generalized pseudospectral method in prolate spheroidal coordinates. We have found that employing this coordinate system makes it possible to avoid emergence of spurious states, which usually show up when solving the Dirac equation numerically. For lower carrier frequencies, interaction with the driving field is described within the dipole approximation. Relativistic effects in the multiphoton ionization probabilities are investigated with respect to the internuclear distance in the quasimolecule. For higher frequencies, the interaction with the field is described beyond the dipole approximation. Nondipole effects in the ionization probability are discussed.
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- 17 September 2018
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
Multiphoton Ionization of One-Electron Relativistic Diatomic Quasimolecules in Strong Laser Fields
by Dmitry A. Telnov, Dmitry A. Krapivin, John Heslar, Shih-I Chu
We perform a theoretical and computational study of relativistic one-electron homonuclear diatomic quasimolecules subject to strong electromagnetic fields linearly polarized along the molecular axis. Several quasimolecules with the nuclear charges 1–92 and appropriately scaled internuclear distances and field parameters are used in the calculations. The time-dependent Dirac equation is solved with the help of the generalized pseudospectral method in prolate spheroidal coordinates. We have found that employing this coordinate system makes it possible to avoid emergence of spurious states, which usually show up when solving the Dirac equation numerically. For lower carrier frequencies, interaction with the driving field is described within the dipole approximation. Relativistic effects in the multiphoton ionization probabilities are investigated with respect to the internuclear distance in the quasimolecule. For higher frequencies, the interaction with the field is described beyond the dipole approximation. Nondipole effects in the ionization probability are discussed.
Cited by 21
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Cited by 22
- 18 April 2018
- Published by American Physical Society (APS) in Physical Review A
Controlling electron quantum paths for generation of circularly polarized high-order harmonics by $H_{2}^{+}$ subject to tailored ( $ω$ , $2 ω$ ) counter-rotating laser fields
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Recently, studies of high-order harmonics (HHG) from atoms driven by bichromatic counter-rotating circularly polarized laser fields as a source of coherent circularly polarized extreme ultraviolet (XUV) and soft-x-ray beams in a tabletop-scale setup have received considerable attention. Here, we demonstrate the ability to control the electron recollisions giving three returns per one cycle of the fundamental frequency $ω$ by using tailored bichromatic ( $ω$ , $2 ω$ ) counter-rotating circularly polarized laser fields with a molecular target. The full control of the electronic pathway is first analyzed by a classical trajectory analysis and then extended to a detailed quantum study of $H_{2}^{+}$ molecules in bichromatic ( $ω$ , $2 ω$ ) counter-rotating circularly polarized laser fields. The radiation spectrum contains doublets of left- and right-circularly polarized harmonics in the XUV ranges. We study in detail the below-, near-, and above-threshold harmonic regions and describe how excited-state resonances alter the ellipticity and phase of the generated harmonic peaks.
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- 18 April 2018
- Published by American Physical Society (APS) in Physical Review A
Open Access
Controlling electron quantum paths for generation of circularly polarized high-order harmonics by $H_{2}^{+}$ subject to tailored ( $ω$ , $2 ω$ ) counter-rotating laser fields
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Recently, studies of high-order harmonics (HHG) from atoms driven by bichromatic counter-rotating circularly polarized laser fields as a source of coherent circularly polarized extreme ultraviolet (XUV) and soft-x-ray beams in a tabletop-scale setup have received considerable attention. Here, we demonstrate the ability to control the electron recollisions giving three returns per one cycle of the fundamental frequency $ω$ by using tailored bichromatic ( $ω$ , $2 ω$ ) counter-rotating circularly polarized laser fields with a molecular target. The full control of the electronic pathway is first analyzed by a classical trajectory analysis and then extended to a detailed quantum study of $H_{2}^{+}$ molecules in bichromatic ( $ω$ , $2 ω$ ) counter-rotating circularly polarized laser fields. The radiation spectrum contains doublets of left- and right-circularly polarized harmonics in the XUV ranges. We study in detail the below-, near-, and above-threshold harmonic regions and describe how excited-state resonances alter the ellipticity and phase of the generated harmonic peaks.
Cited by 22
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Cited by 24
- 5 December 2017
- Published by American Physical Society (APS) in Physical Review A
Generation of circularly polarized XUV and soft-x-ray high-order harmonics by homonuclear and heteronuclear diatomic molecules subject to bichromatic counter-rotating circularly polarized intense laser fields
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Recently, studies of bright circularly polarized high-harmonic beams from atoms in the soft-x-ray region as a source for x-ray magnetic circular dichroism measurement in a tabletop-scale setup have received considerable attention. In this paper, we address the problem with molecular targets and perform a detailed quantum study of ${H_{2}}^{+}$ , CO, and $N_{2}$ molecules in bichromatic counter-rotating circularly polarized laser fields where we adopt wavelengths (1300 and 790 nm) and intensities ( $2 \times 10^{14} W / {cm}^{2}$ ) reported in a recent experiment [ Proc. Natl. Acad. Sci. USA 112, 14206 (2015)]. Our treatment of multiphoton processes in homonuclear and heteronuclear diatomic molecules is nonperturbative and based on the time-dependent density-functional theory for multielectron systems. The calculated radiation spectrum contains doublets of left and right circularly polarized harmonics with high-energy photons in the XUV and soft-x-ray ranges. Our results reveal intriguing and substantially different nonlinear optical responses for homonuclear and heteronuclear diatomic molecules subject to circularly polarized intense laser fields. We study in detail the below- and above-threshold harmonic regions and analyze the ellipticity and phase of the generated harmonic peaks.
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- 5 December 2017
- Published by American Physical Society (APS) in Physical Review A
Generation of circularly polarized XUV and soft-x-ray high-order harmonics by homonuclear and heteronuclear diatomic molecules subject to bichromatic counter-rotating circularly polarized intense laser fields
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Recently, studies of bright circularly polarized high-harmonic beams from atoms in the soft-x-ray region as a source for x-ray magnetic circular dichroism measurement in a tabletop-scale setup have received considerable attention. In this paper, we address the problem with molecular targets and perform a detailed quantum study of ${H_{2}}^{+}$ , CO, and $N_{2}$ molecules in bichromatic counter-rotating circularly polarized laser fields where we adopt wavelengths (1300 and 790 nm) and intensities ( $2 \times 10^{14} W / {cm}^{2}$ ) reported in a recent experiment [ Proc. Natl. Acad. Sci. USA 112, 14206 (2015)]. Our treatment of multiphoton processes in homonuclear and heteronuclear diatomic molecules is nonperturbative and based on the time-dependent density-functional theory for multielectron systems. The calculated radiation spectrum contains doublets of left and right circularly polarized harmonics with high-energy photons in the XUV and soft-x-ray ranges. Our results reveal intriguing and substantially different nonlinear optical responses for homonuclear and heteronuclear diatomic molecules subject to circularly polarized intense laser fields. We study in detail the below- and above-threshold harmonic regions and analyze the ellipticity and phase of the generated harmonic peaks.
Cited by 24
Open Access
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Cited by 30
- 26 April 2017
- Published by American Physical Society (APS) in Physical Review A
High-order-harmonic generation of vibrating ${H_{2}}^{+}$ and ${D_{2}}^{+}$
by Dmitry A. Telnov, John Heslar, Shih-I Chu
We study the isotope effect on high-order-harmonic generation (HHG) of vibrating ${H_{2}}^{+}$ and ${D_{2}}^{+}$ molecular ions aligned parallel to the polarization of the laser field. The time-dependent Schrödinger equation is solved accurately and efficiently by the time-dependent generalized pseudospectral and Fourier grid methods in three spatial coordinates, one of them being the internuclear separation and the other two describing the electronic motion. The laser pulses have a carrier wavelength of 800 nm and duration of 10 or 16 optical cycles. The peak intensities used in the calculations are $2 \times 10^{14}$ and $3 \times 10^{14} W / {cm}^{2}$ . The effect of nuclear vibration is visible in both ${H_{2}}^{+}$ and ${D_{2}}^{+}$ but more pronounced in the lighter ${H_{2}}^{+}$ molecule. Striking differences from the fixed nuclei case are a total disappearance of the traditional plateau in the HHG spectrum at the higher intensity and significant redshift of the harmonic peaks in the central part of the spectrum. These phenomena are explained based on the analysis of the dynamics of the nuclear vibrational wave packet.
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- 26 April 2017
- Published by American Physical Society (APS) in Physical Review A
Open Access
High-order-harmonic generation of vibrating ${H_{2}}^{+}$ and ${D_{2}}^{+}$
by Dmitry A. Telnov, John Heslar, Shih-I Chu
We study the isotope effect on high-order-harmonic generation (HHG) of vibrating ${H_{2}}^{+}$ and ${D_{2}}^{+}$ molecular ions aligned parallel to the polarization of the laser field. The time-dependent Schrödinger equation is solved accurately and efficiently by the time-dependent generalized pseudospectral and Fourier grid methods in three spatial coordinates, one of them being the internuclear separation and the other two describing the electronic motion. The laser pulses have a carrier wavelength of 800 nm and duration of 10 or 16 optical cycles. The peak intensities used in the calculations are $2 \times 10^{14}$ and $3 \times 10^{14} W / {cm}^{2}$ . The effect of nuclear vibration is visible in both ${H_{2}}^{+}$ and ${D_{2}}^{+}$ but more pronounced in the lighter ${H_{2}}^{+}$ molecule. Striking differences from the fixed nuclei case are a total disappearance of the traditional plateau in the HHG spectrum at the higher intensity and significant redshift of the harmonic peaks in the central part of the spectrum. These phenomena are explained based on the analysis of the dynamics of the nuclear vibrational wave packet.
Cited by 30
Open Access
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Cited by 15
- 17 April 2017
- Published by American Physical Society (APS) in Physical Review A
Probing multirescattering dynamics and electron quantum paths for below- and near-threshold harmonic generation of $H_{2}$ in an intense laser field
by John Heslar, Shih-I Chu
Most previous studies of high-order-harmonic generation have focused on the regime beyond the ionization threshold; the dynamical origin of below- and near-threshold harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here, we report a self-interaction free time-dependent density-functional-theory study along with an extended semiclassical study for the nonperturbative probing of the dynamical origin of below- and near-threshold harmonic generation of the $H_{2}$ molecule in an intense near-infrared laser field. Our approach allows an accurate study of the electron trajectories as a function of energy, time, and position for below-, near-, and above-threshold harmonics for electrons departing initially from each of the individual hydrogen cores of the $H_{2}$ molecule. We discover that short trajectories are multiphoton dominated and can have multiple returns for below-threshold harmonics, and excited-state resonances can have significant effects on the generation of neighboring below-threshold harmonics. Furthermore, we find that the electron dynamics for below-threshold long, short, and resonant trajectories differ greatly depending upon which hydrogen core (left or right) the electron was released from initially. An intuitive and appealing picture of near- and below-threshold harmonic generation discovered in our study can give guidance to future experiments in this forefront area of ultrafast atomic, molecular, and optical physics.
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- 17 April 2017
- Published by American Physical Society (APS) in Physical Review A
Open Access
Probing multirescattering dynamics and electron quantum paths for below- and near-threshold harmonic generation of $H_{2}$ in an intense laser field
by John Heslar, Shih-I Chu
Most previous studies of high-order-harmonic generation have focused on the regime beyond the ionization threshold; the dynamical origin of below- and near-threshold harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here, we report a self-interaction free time-dependent density-functional-theory study along with an extended semiclassical study for the nonperturbative probing of the dynamical origin of below- and near-threshold harmonic generation of the $H_{2}$ molecule in an intense near-infrared laser field. Our approach allows an accurate study of the electron trajectories as a function of energy, time, and position for below-, near-, and above-threshold harmonics for electrons departing initially from each of the individual hydrogen cores of the $H_{2}$ molecule. We discover that short trajectories are multiphoton dominated and can have multiple returns for below-threshold harmonics, and excited-state resonances can have significant effects on the generation of neighboring below-threshold harmonics. Furthermore, we find that the electron dynamics for below-threshold long, short, and resonant trajectories differ greatly depending upon which hydrogen core (left or right) the electron was released from initially. An intuitive and appealing picture of near- and below-threshold harmonic generation discovered in our study can give guidance to future experiments in this forefront area of ultrafast atomic, molecular, and optical physics.
Cited by 15
Open Access
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Cited by 15
- 24 November 2016
- Published by Springer Nature in Scientific Reports
Unravelling the dynamical origin of below- and near-threshold harmonic generation of H2+ in an intense NIR laser field
by John Heslar, Shih-I. Chu
Recently, the study of near- and below- threshold regime harmonics as a potential source of intense coherent vacuum-ultraviolet radiation has received considerable attention. However, the dynamical origin of these lower harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here we perform the first fully ab initio and high precision 3D quantum study of the below- and near-threshold harmonic generation of molecules in an intense 800-nm near-infrared (NIR) laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, we explore in-depth the roles of various quantum trajectories, including short- and long trajectories, multiphoton trajectories, resonance-enhanced trajectories, and multiple rescattering trajectories of the below- and near- threshold harmonic generation processes. Our results shed new light on the dynamical origin of the below- and near-threshold harmonic generation and various quantum trajectories for diatomic molecules for the first time.
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- 24 November 2016
- Published by Springer Nature in Scientific Reports
Open Access
Unravelling the dynamical origin of below- and near-threshold harmonic generation of H2+ in an intense NIR laser field
by John Heslar, Shih-I. Chu
Recently, the study of near- and below- threshold regime harmonics as a potential source of intense coherent vacuum-ultraviolet radiation has received considerable attention. However, the dynamical origin of these lower harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here we perform the first fully ab initio and high precision 3D quantum study of the below- and near-threshold harmonic generation of molecules in an intense 800-nm near-infrared (NIR) laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, we explore in-depth the roles of various quantum trajectories, including short- and long trajectories, multiphoton trajectories, resonance-enhanced trajectories, and multiple rescattering trajectories of the below- and near- threshold harmonic generation processes. Our results shed new light on the dynamical origin of the below- and near-threshold harmonic generation and various quantum trajectories for diatomic molecules for the first time.
Cited by 15
Open Access
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Cited by 19
- 1 June 2016
- Published by American Physical Society (APS) in Physical Review A
Enhancement of VUV and EUV generation by field-controlled resonance structures of diatomic molecules
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Below- and near-threshold harmonic generation provides a potential approach to achieve a high conversion efficiency of vacuum-ultraviolet and extreme-ultraviolet sources for the advancement of spectroscopy. Here, we perform a time-dependent density functional theory study for the nonperturbative treatment of below- and near-threshold harmonic generation of CO and $N_{2}$ diatomic molecules subject to short near-infrared laser pulses and aligned parallel to the laser field polarization. We find that with the use of different driving laser pulse shapes, we can control and enhance harmonic generation through the excited-state resonance structures. Depending on the pulse shape, the enhancement can reach five to seven orders of magnitude as compared to the reference sine-squared laser pulse of the same duration. The results for different driving laser intensities are also presented and discussed in detail.
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- 1 June 2016
- Published by American Physical Society (APS) in Physical Review A
Open Access
Enhancement of VUV and EUV generation by field-controlled resonance structures of diatomic molecules
by John Heslar, Dmitry A. Telnov, Shih-I Chu
Below- and near-threshold harmonic generation provides a potential approach to achieve a high conversion efficiency of vacuum-ultraviolet and extreme-ultraviolet sources for the advancement of spectroscopy. Here, we perform a time-dependent density functional theory study for the nonperturbative treatment of below- and near-threshold harmonic generation of CO and $N_{2}$ diatomic molecules subject to short near-infrared laser pulses and aligned parallel to the laser field polarization. We find that with the use of different driving laser pulse shapes, we can control and enhance harmonic generation through the excited-state resonance structures. Depending on the pulse shape, the enhancement can reach five to seven orders of magnitude as compared to the reference sine-squared laser pulse of the same duration. The results for different driving laser intensities are also presented and discussed in detail.
Cited by 19
Open Access
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Cited by 16
- 19 February 2015
- Published by American Physical Society (APS) in Physical Review A
Subcycle dynamics of high-harmonic generation in valence-shell and virtual states of Ar atoms: A self-interaction-free time-dependent density-functional-theory approach
by John Heslar, Dmitry A. Telnov, Shih-I Chu
We perform an ab initio all-electron study of the subcycle structure, dynamics, and spectra of high harmonic generation (HHG) processes of Ar atoms in the presence of extreme ultraviolet (XUV) attosecond pulses and near-infrared (NIR) laser fields by means of the self-interaction-free time-dependent density functional theory (TDDFT). The TDDFT equations are solved accurately and efficiently via the time-dependent generalized pseudospectral (TDGPS) method. We focus on the subcycle (with respect to NIR field) temporal behavior of the level shift of the excited energy levels and related dynamics of harmonic photon emission. We observe and identify the subcycle shifts in the harmonic emission spectrum as a function of the time delay between the XUV and NIR pulses. In the region where the two pulses overlap, the photon emission peaks have an oscillatory structure with a period of $\sim 1.3$ fs, which is half of the NIR laser optical cycle. We present and analyze the harmonic emission spectra from $3 s n p_{0}, 3 p_{0} n s, 3 p_{1} n d_{1}, 3 p_{1} n p_{1}, 3 p_{0} n d_{0}, 3 p_{0} n p_{0}$ , and $3 p_{0} n s$ excited states and the $3 p_{0} 4 p_{0}^{-}$ virtual state as functions of the time delay. In addition, we explore the subcycle a.c. Stark shift phenomenon in NIR fields and its influence on the harmonic emission process. Our analysis reveals several features of the subcycle HHG dynamics and spectra as well as a temporal energy level shift.
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- 19 February 2015
- Published by American Physical Society (APS) in Physical Review A
Open Access
Subcycle dynamics of high-harmonic generation in valence-shell and virtual states of Ar atoms: A self-interaction-free time-dependent density-functional-theory approach
by John Heslar, Dmitry A. Telnov, Shih-I Chu
We perform an ab initio all-electron study of the subcycle structure, dynamics, and spectra of high harmonic generation (HHG) processes of Ar atoms in the presence of extreme ultraviolet (XUV) attosecond pulses and near-infrared (NIR) laser fields by means of the self-interaction-free time-dependent density functional theory (TDDFT). The TDDFT equations are solved accurately and efficiently via the time-dependent generalized pseudospectral (TDGPS) method. We focus on the subcycle (with respect to NIR field) temporal behavior of the level shift of the excited energy levels and related dynamics of harmonic photon emission. We observe and identify the subcycle shifts in the harmonic emission spectrum as a function of the time delay between the XUV and NIR pulses. In the region where the two pulses overlap, the photon emission peaks have an oscillatory structure with a period of $\sim 1.3$ fs, which is half of the NIR laser optical cycle. We present and analyze the harmonic emission spectra from $3 s n p_{0}, 3 p_{0} n s, 3 p_{1} n d_{1}, 3 p_{1} n p_{1}, 3 p_{0} n d_{0}, 3 p_{0} n p_{0}$ , and $3 p_{0} n s$ excited states and the $3 p_{0} 4 p_{0}^{-}$ virtual state as functions of the time delay. In addition, we explore the subcycle a.c. Stark shift phenomenon in NIR fields and its influence on the harmonic emission process. Our analysis reveals several features of the subcycle HHG dynamics and spectra as well as a temporal energy level shift.
Cited by 16
Open Access
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Cited by 22
- 4 December 2014
- Published by American Physical Society (APS) in Physical Review A
Effect of nuclear vibration on high-order-harmonic generation of aligned ${H_{2}}^{+}$ molecules
by Dmitry A. Telnov, John Heslar, Shih-I Chu
High-order-harmonic generation (HHG) spectra have been calculated for ${H_{2}}^{+}$ molecules aligned parallel to the polarization of the laser field. We make use of the Jacobi coordinates and neglect the rotation of the nuclei. The remaining time-dependent Schrödinger equation is three dimensional in spatial coordinates, one of them being the internuclear separation and the other two describing the electronic motion. The problem is solved using the accurate and efficient time-dependent generalized pseudospectral method in prolate spheroidal coordinates for the electronic coordinates and Fourier grid method for the internuclear separation. Laser pulses with a carrier wavelength of 800 nm, a duration of ten optical cycles, and a peak intensity of $2 \times 10^{14}$ ${W/cm}^{2}$ have been used in the calculations. Our HHG spectra, which incorporate the effect of nuclear vibration, generally exhibit a significant deviation from those calculated for the fixed internuclear separations. The low-energy regions of the spectra, however, resemble those for the nuclei fixed at larger separations, while the high-energy regions are closer to those for the nuclei fixed at smaller internuclear distances. The dynamics of the nuclear vibrational wave packet is also obtained and analyzed.
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- 4 December 2014
- Published by American Physical Society (APS) in Physical Review A
Open Access
Effect of nuclear vibration on high-order-harmonic generation of aligned ${H_{2}}^{+}$ molecules
by Dmitry A. Telnov, John Heslar, Shih-I Chu
High-order-harmonic generation (HHG) spectra have been calculated for ${H_{2}}^{+}$ molecules aligned parallel to the polarization of the laser field. We make use of the Jacobi coordinates and neglect the rotation of the nuclei. The remaining time-dependent Schrödinger equation is three dimensional in spatial coordinates, one of them being the internuclear separation and the other two describing the electronic motion. The problem is solved using the accurate and efficient time-dependent generalized pseudospectral method in prolate spheroidal coordinates for the electronic coordinates and Fourier grid method for the internuclear separation. Laser pulses with a carrier wavelength of 800 nm, a duration of ten optical cycles, and a peak intensity of $2 \times 10^{14}$ ${W/cm}^{2}$ have been used in the calculations. Our HHG spectra, which incorporate the effect of nuclear vibration, generally exhibit a significant deviation from those calculated for the fixed internuclear separations. The low-energy regions of the spectra, however, resemble those for the nuclei fixed at larger separations, while the high-energy regions are closer to those for the nuclei fixed at smaller internuclear distances. The dynamics of the nuclear vibrational wave packet is also obtained and analyzed.
Cited by 22
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Cited by 11
- 21 May 2014
- Published by American Physical Society (APS) in Physical Review A
Subcycle dynamics of high-order-harmonic generation of He atoms excited by attosecond pulses and driven by near-infrared laser fields: A self-interaction-free time-dependent density-functional-theory approach
by John Heslar, Dmitry A. Telnov, Shih-I Chu
In the framework of the self-interaction-free time-dependent density-functional theory, we have performed three-dimensional (3D) ab initio calculations of He atoms in near-infrared (NIR) laser fields subject to excitation by a single extreme ultraviolet (XUV) attosecond pulse (SAP). We have explored the dynamical behavior of the subcycle high harmonic generation (HHG) for transitions from the excited states to the ground state and found oscillation structures with respect to the time delay between the SAP and NIR fields. The oscillatory pattern in the photon emission spectra has a period of $$\sim${}$$1.3$ fs which is half of the NIR laser optical cycle, similar to that recently measured in the experiments on transient absorption of He [M. Chini et al., Sci. Rep. 3, 1105 (2013)]. We present the photon emission spectra from $1s2p$, $1s3p$, $1s4p$, $1s5p$, and $1s6p$ excited states as functions of the time delay. We explore the subcycle Stark shift phenomenon in NIR fields and its influence on the photon emission process. Our analysis reveals several interesting features of the subcycle HHG dynamics and we identify the mechanisms responsible for the observed peak splitting in the photon emission spectra.
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- 21 May 2014
- Published by American Physical Society (APS) in Physical Review A
Subcycle dynamics of high-order-harmonic generation of He atoms excited by attosecond pulses and driven by near-infrared laser fields: A self-interaction-free time-dependent density-functional-theory approach
by John Heslar, Dmitry A. Telnov, Shih-I Chu
In the framework of the self-interaction-free time-dependent density-functional theory, we have performed three-dimensional (3D) ab initio calculations of He atoms in near-infrared (NIR) laser fields subject to excitation by a single extreme ultraviolet (XUV) attosecond pulse (SAP). We have explored the dynamical behavior of the subcycle high harmonic generation (HHG) for transitions from the excited states to the ground state and found oscillation structures with respect to the time delay between the SAP and NIR fields. The oscillatory pattern in the photon emission spectra has a period of $$\sim${}$$1.3$ fs which is half of the NIR laser optical cycle, similar to that recently measured in the experiments on transient absorption of He [M. Chini et al., Sci. Rep. 3, 1105 (2013)]. We present the photon emission spectra from $1s2p$, $1s3p$, $1s4p$, $1s5p$, and $1s6p$ excited states as functions of the time delay. We explore the subcycle Stark shift phenomenon in NIR fields and its influence on the photon emission process. Our analysis reveals several interesting features of the subcycle HHG dynamics and we identify the mechanisms responsible for the observed peak splitting in the photon emission spectra.
Cited by 11

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