Pulse-delay effects in the angular distribution of near-threshold EUV + IR two-photon ionization of Ne

Mondal, Subhendu; Fukuzawa, H.; Motomura, K.; Tachibana, Takehiko; Nagaya, K.; Sakai, Tsukasa; Matsunami, K.; Yase, S.; Yao, Makoto; Wada, S.; Hayashita, H.; Saitô, Norio; Callegari, Carlo; Miron, Catalin; Nagasono, Mitsuru; Togashi, Tadashi; Yabashi, Makina; Ishikawa, Kenichi L.; Kazansky, A. K.; Кабачник, Н. М.; Ueda, Kiyoshi

doi:10.1103/physreva.89.013415

Cited by 14 publications

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“…An alternative to the approach of varying the relative polarizations of IR and VUV radiation by angular detection of the photoelectrons was established for He and Ar in Refs. [23][24][25][26][27][28][29]. This enabled studying the dependence of the TCATI electron angular distributions on their kinetic energy and on the photon energy of the dressing field [26], and it was used to determine the polarization state of a VUV free-electron laser source [28].…”

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confidence: 99%

“…Can we "turn the tables" on polarization-controlled TCATI as it has been applied so far and use the polarization dependence of the TCATI sideband electrons to extract information on the angular distribution of the main photoelectron lines in molecules? This could add an approach to the suite of methods for measuring the angular distribution of photoelectrons in molecules [34] by angular-resolved detection of the electrons with two or more electron energy analyzers [34][35][36][37][38][39], by imaging the electron trajectories with, e.g., velocity map imaging [23][24][25][26][27][28][29], by aligning or orienting the target in space [40][41][42][43][44][45], or by performing the measurement in the molecular frame by correlating ion and electron momenta with, e.g., coincidence techniques [46][47][48]. Here we present our combined experimental and theoretical investigation of polarization-controlled TCATI in gaseous H 2 O, O 2 , and N 2 .…”

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confidence: 99%

“…Although none of these values is close to the value determined here (Table II), this interference could still explain the discrepancy between the measured and modeled anisotropy parameter as it was not included in our model. Measuring the dependence of the sideband electron angular distribution on the time delay between VUV and IR pulses was recently demonstrated to be sensitive to the relative importance of resonant and nonresonant ionization pathways [29] and could be one way to test this hypothesis.…”

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Probing photoelectron angular distributions in molecules with polarization-controlled two-color above-threshold ionization

et al. 2015

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We present polarization-controlled multiphoton two-color above-threshold ionization (TCATI) of molecules. The intensity modulations of valence photoelectron intensities of molecules arising from varying the relative orientation of the linear polarization vectors of femtosecond infrared (IR) and vacuum-ultraviolet (VUV) radiation in TCATI of the highest occupied molecular orbitals of H 2 O, O 2 , and N 2 are reported. The results on the molecular systems are compared to the 3p photoionization of atomic Ar, which serves as a reference system. Modeling the large differences of the modulation amplitudes within the soft-photon approximation enables us to extract the one-photon-ionization anisotropy parameter β 2 . Accounting only for the first sideband due to two-photon TCATI by one VUV and one IR photon we find satisfactory agreement between experiment and simulation for H 2 O and O 2 . However, the model fails for N 2 and possible reasons are discussed. We discuss that the described approach may represent an alternative way of determining photoelectron angular distributions from valence shells of molecules and indicate future directions for modeling TCATI of molecules. The occurrence of sidebands in atomic photoemission with femtosecond vacuum-ultraviolet (VUV) pulses in the presence of an infrared (IR) dressing field was already discovered more than 20 years ago for the laser-assisted Auger decay (LAAD) [1] and for two-color above-threshold ionization (TCATI) [2]. Sidebands occur when the photon density of the dressing field is high enough to enable simultaneous absorption or emission of one or more IR photons by the photoelectron arising from ionization with the VUV pulse [3,4]. They are expressed in the spectra as satellite lines shifted in kinetic energy with respect to the main line from single-photon VUV ionization by the energy of one or more IR photons. As the sideband intensity represents a cross-correlation signal of the femtosecond IR and VUV pulses, two-photon TCATI on gaseous as well as solid samples has ever since been used to determine the temporal resolution in pump-probe photoelectron spectroscopy experiments with laboratory VUV and soft x-ray sources and free-electron lasers (FELs) [5][6][7][8][9][10][11][12][13][14][15][16][17].In TCATI in atoms it was discovered that the sideband intensity depends on the relative orientations of the linear polarization vectors of IR and VUV radiation [18,19]. This effect was then used in polarization-controlled TCATI to extract the angular distribution and the symmetry of the outgoing TCATI electron waves in He as a function of the dressing photon field density [20]. The polarization dependence in TCATI can be understood in terms of polarization-dependent coupling of the intermediate states with the continua, and the angular distribution is in general described by two asymmetry parameters, β 2 and β 4 [21,22] An atomic model connecting sideband polarization sensitivity with the one-photon-ionization anisotropy parameter β 2 , which characterizes the photoelectro...

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Probing photoelectron angular distributions in molecules with polarization-controlled two-color above-threshold ionization

et al. 2015

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“…The difference between these two extreme cases clearly demonstrates that the PAD in TPSI strongly depends on the time delay between the pulses. The corresponding theoretical calculations agree with the measurements and explain the dependence by the change in the relative contribution of resonant and nonresonant ionization paths [43].…”

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confidence: 50%

“…[43]. It was shown experimentally that the PAD in two-color TPSI of Ne atoms is notably different for temporally overlapping and nonoverlapping EUV and IR pulses.…”

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confidence: 97%

Theoretical study of pulse delay effects in the photoelectron angular distribution of near-thresholdEUV+IRtwo-photon ionization of atoms

et al. 2014

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We study theoretically the photoelectron angular distributions (PADs) from two-color two-photon nearthreshold ionization of hydrogen and noble gas (He, Ne, and Ar) atoms by a combined action of femtosecond extreme ultraviolet (EUV) and near-infrared (IR) laser pulses. By using second-order time-dependent perturbation theory, we clarify how the two-photon ionization process depends on the EUV-IR pulse delay and how it is connected to the interplay between resonant and nonresonant ionization paths. Furthermore, by solving the time-dependent Schrödinger equation, we calculate the anisotropy parameters β 2 and β 4 as well as the amplitude ratio and relative phase between partial waves characterizing the PADs. We show that, in general, these parameters notably depend on the time delay between the EUV and IR pulses, except for He. This dependence is related to the varying relative role of resonant and nonresonant paths of photoionization. Our numerical results for H, He, Ne, and Ar show that the pulse-delay effect is more pronounced for p-shell ionization than for s-shell ionization.

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Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

et al. 2021

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Pulse-delay effects in the angular distribution of near-threshold EUV + IR two-photon ionization of Ne

Cited by 14 publications

References 28 publications

Probing photoelectron angular distributions in molecules with polarization-controlled two-color above-threshold ionization

Probing photoelectron angular distributions in molecules with polarization-controlled two-color above-threshold ionization

Theoretical study of pulse delay effects in the photoelectron angular distribution of near-thresholdEUV+IRtwo-photon ionization of atoms

Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

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