The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Yunquan Liu - One of the best experts on this subject based on the ideXlab platform.
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laser wavelength and intensity dependence of electron nuclear energy sharing in dissociative ionization of h 2
Physical Review A, 2020Co-Authors: Hao Liang, Yunquan Liu, Mingming Liu, Liangyou PengAbstract:We experimentally and theoretically study the Photoelectron-nuclear energy sharing mechanism of the correlated dynamics between the Photoelectrons and the fragmented ions in the dissociative ionization of ${\mathrm{H}}_{2}$ with respect to the laser intensity at the wavelengths $\ensuremath{\lambda}=395\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ and $\ensuremath{\lambda}=790\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$. We show that the prominent Photoelectron-nuclear energy sharing along the back-diagonal lines is only observed for 395 nm at lower intensities, which is absent for increased intensities at 395 nm and for 790 nm lasers over a wide range of intensities. Based on a quantum mechanical model that includes the correlation between the Photoelectron and the parent ion, we show that bond hardening has a significant effect on the Photoelectron-nuclear energy sharing. The resonant states of the neutral hydrogen molecule during strong-field ionization and the distribution of vibrational states of molecular ions determine the joint energy spectrum of Photoelectrons and nuclei. The study provides an intuitive and comprehensive description and understanding of the correlated Photoelectron-nuclear dynamics in the dissociative ionization.
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energy resolved ultrashort delays of Photoelectron emission clocked by orthogonal two color laser fields
Physical Review Letters, 2017Co-Authors: Xiaochun Gong, Yunquan Liu, Wenbin Zhang, Kang Lin, Cheng Lin, Qiying Song, Heping Zeng, Weifeng YangAbstract:A phase-controlled orthogonal two-color (OTC) femtosecond laser pulse is employed to probe the time delay of Photoelectron emission in the strong-field ionization of atoms. The OTC field spatiotemporally steers the emission dynamics of the Photoelectrons and meanwhile allows us to unambiguously distinguish the main and sideband peaks of the above-threshold ionization spectrum. The relative phase shift between the main and sideband peaks, retrieved from the phase-of-phase of the Photoelectron spectrum as a function of the laser phase, gradually decreases with increasing electron energy, and becomes zero for the fast electron which is mainly produced by the rescattering process. Furthermore, a Freeman resonance delay of 140±40 attoseconds between Photoelectrons emitted via the 4f and 5p Rydberg states of argon is observed.
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Fully differential measurement on above-threshold ionization of CO and CO_2 molecules in strong laser fields
Journal of The Optical Society of America B-optical Physics, 2011Co-Authors: Xianrong Liu, Yunquan Liu, Hong Liu, Yongkai Deng, Qihuang GongAbstract:We present a fully differential measurement on above-threshold ionization of diatomic (CO) and linear triatomic (CO2) molecules in strong femtosecond laser fields (25fs, 795nm) at a laser intensity of ∼8×1013W/cm2. The Photoelectron longitudinal momentum distribution of CO in the laser polarization direction shows a broader distribution near zero momentum in the laser polarization plane with a shoulder around 0.38a.u., whereas it shows a clear maximum for CO2. The relative Photoelectron yields near zero longitudinal momentum are less dependent on the laser intensity. The difference may result from the molecular structure. Even though molecular targets have different binding energy and outer orbitals, the near-threshold Photoelectrons have similar angular distribution, and the dominant angular momentum of the near-threshold Photoelectron is L=4 (ng Rydberg state) for both targets.
Steven Pratt - One of the best experts on this subject based on the ideXlab platform.
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Time-resolved Photoelectron spectroscopy of the CH3I B1E 6s [2] state
Physical Chemistry Chemical Physics, 2010Co-Authors: Nicolas Thiré, Raluca Cireasa, Valérie Blanchet, Steven PrattAbstract:The predissociation dynamics of the vibrationless level of the 6s (B 2E) Rydberg state of CH3I was studied by femtosecond-resolved velocity map imaging of Photoelectrons. By monitoring the decay of the CH3I+ produced by photoionizing the B state, the predissociation lifetime was measured to be 1310 ± 70 fs. Photoelectron spectra were recorded as a function of the excitation scheme (one or two photons to the B state), and as a function of the ionizing wavelength. All of these Photoelectron spectra show a simple time dependence that is consistent with the decay time of the CH3I+ ion signal. The Photoelectron angular distributions for the ionization of the B state depend on the excitation scheme and the ionizing wavelength, and show a strong dependence on the vibrational modes excited in the resulting CH3I+. At long delays, the Photoelectron spectra are characterized by photoionization of the I(2P1/2) fragment formed by predissociation of the B state.
W K Peterson - One of the best experts on this subject based on the ideXlab platform.
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Solar EUV and XUV energy input to thermosphere on solar rotation time scales derived from Photoelectron observations
Journal of Geophysical Research, 2012Co-Authors: W K Peterson, Juan Fontenla, W. Kent Tobiska, Thomas N Woods, Phillip C Chamberlin, P G Richards, Stanley C Solomon, Harry WarrenAbstract:[1] Solar radiation below ∼100 nm produces Photoelectrons, a substantial portion of the F region ionization, most of the E region ionization, and drives chemical reactions in the thermosphere. Unquantified uncertainties in thermospheric models exist because of uncertainties in solar irradiance models used to fill spectral and temporal gaps in solar irradiance observations. We investigate uncertainties in solar energy input to the thermosphere on solar rotation time scales using Photoelectron observations from the FAST satellite. We compare observed and modeled Photoelectron energy spectra using two Photoelectron production codes driven by five different solar irradiance models. We observe about 1.7% of the ionizing solar irradiance power in the escaping Photoelectron flux. Most of the code/model pairs used reproduce the average escaping Photoelectron flux over a 109-day interval in late 2006. The code/model pairs we used do not completely reproduce the observed spectral and solar rotation variations in Photoelectron power density. For the interval examined, 30% of the variability in Photoelectron power density with equivalent wavelengths between 18 and 45 nm was not captured in the code/model pairs. For equivalent wavelengths below ∼16 nm, most of the variability was missed. This result implies that thermospheric model runs based on the solar irradiance models we tested systematically underestimate the energy input from ionizing radiation on solar rotation time scales.
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time scales derived from Photoelectron observations.
2011Co-Authors: W K Peterson, Juan Fontenla, W. Kent Tobiska, Thomas N Woods, Phillip C Chamberlin, P G Richards, Stanley C Solomon, Harry P. WarrenAbstract:Solar radiation below ~100 nm produces Photoelectrons, a substantial portion of the F 16 region ionization, most of the E region ionization, and drives chemical reactions in the 17 thermosphere. Unquantified uncertainties in thermospheric models exist because of 18 uncertainties in solar irradiance models used to fill spectral and temporal gaps in solar 19 irradiance observations. We investigate uncertainties in solar energy input to the 20 thermosphere on solar rotation time scales using Photoelectron observations from the FAST 21 satellite. We compare observed and modeled Photoelectron energy spectra using two 22 Photoelectron production codes driven by five different solar irradiance models. We observe 23 about 1.7% of the ionizing solar irradiance power in the escaping Photoelectron flux. Most of 24 the code/model pairs used reproduce the average escaping Photoelectron flux over a 109-day 25 interval in late 2006. The code/model pairs we used do not completely reproduce the 26 observed spectral and solar cycle variations in Photoelectron power density. For the interval 27 examined, 30% of the variability in Photoelectron power density with equivalent 28
Harry Warren - One of the best experts on this subject based on the ideXlab platform.
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Solar EUV and XUV energy input to thermosphere on solar rotation time scales derived from Photoelectron observations
Journal of Geophysical Research, 2012Co-Authors: W K Peterson, Juan Fontenla, W. Kent Tobiska, Thomas N Woods, Phillip C Chamberlin, P G Richards, Stanley C Solomon, Harry WarrenAbstract:[1] Solar radiation below ∼100 nm produces Photoelectrons, a substantial portion of the F region ionization, most of the E region ionization, and drives chemical reactions in the thermosphere. Unquantified uncertainties in thermospheric models exist because of uncertainties in solar irradiance models used to fill spectral and temporal gaps in solar irradiance observations. We investigate uncertainties in solar energy input to the thermosphere on solar rotation time scales using Photoelectron observations from the FAST satellite. We compare observed and modeled Photoelectron energy spectra using two Photoelectron production codes driven by five different solar irradiance models. We observe about 1.7% of the ionizing solar irradiance power in the escaping Photoelectron flux. Most of the code/model pairs used reproduce the average escaping Photoelectron flux over a 109-day interval in late 2006. The code/model pairs we used do not completely reproduce the observed spectral and solar rotation variations in Photoelectron power density. For the interval examined, 30% of the variability in Photoelectron power density with equivalent wavelengths between 18 and 45 nm was not captured in the code/model pairs. For equivalent wavelengths below ∼16 nm, most of the variability was missed. This result implies that thermospheric model runs based on the solar irradiance models we tested systematically underestimate the energy input from ionizing radiation on solar rotation time scales.
Nicolas Thiré - One of the best experts on this subject based on the ideXlab platform.
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Time-resolved Photoelectron spectroscopy of the CH3I B1E 6s [2] state
Physical Chemistry Chemical Physics, 2010Co-Authors: Nicolas Thiré, Raluca Cireasa, Valérie Blanchet, Steven PrattAbstract:The predissociation dynamics of the vibrationless level of the 6s (B 2E) Rydberg state of CH3I was studied by femtosecond-resolved velocity map imaging of Photoelectrons. By monitoring the decay of the CH3I+ produced by photoionizing the B state, the predissociation lifetime was measured to be 1310 ± 70 fs. Photoelectron spectra were recorded as a function of the excitation scheme (one or two photons to the B state), and as a function of the ionizing wavelength. All of these Photoelectron spectra show a simple time dependence that is consistent with the decay time of the CH3I+ ion signal. The Photoelectron angular distributions for the ionization of the B state depend on the excitation scheme and the ionizing wavelength, and show a strong dependence on the vibrational modes excited in the resulting CH3I+. At long delays, the Photoelectron spectra are characterized by photoionization of the I(2P1/2) fragment formed by predissociation of the B state.
