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Light-induced deprotonation of molecules is an important process in photochemical reactions. Here, we theoretically investigate the tunneling deprotonation of H 2 + and its asymmetric isotopologues driven by circularly polarized THz laser pulses. The quasi-static picture shows that the field-dressed potential barrier is significantly lowered for the deprotonation channel when the mass asymmetry of the diatomic molecule increases. Our numerical simulations demonstrate that when the mass symmetry breaks, the tunneling deprotonation is significantly enhanced and the proton tunneling becomes the dominant dissociation channel in the THz driving fields. In addition, the simulated nuclear momentum distributions show that the emission of the proton is directed by the effective vector potential for the deprotonation channel and, meanwhile, the angular distribution of the emitting proton is affected by the alignment and rotation of the molecule induced by the rotating field. [ABSTRACT FROM AUTHOR]

We experimentally study two-body Coulomb explosions of CO2, O2, and CH3Cl molecules in intense femtosecond laser pulses. We observe an obvious variation in the ionic angular distribution of the fragments with respect to the kinetic energy releases (KERs). Using a classical model based on ab initio potential energy curves, we find that the dependence of the ionic angular distribution on the KER is relevant to the fact that the accurate potential energy deviates significantly from the value determined by applying the Coulomb interaction approximation at a relatively small internuclear distance of the molecule. We show that the KER-dependent ionic angular distribution provides an effective way to determine the critical internuclear distance at which the Coulomb interaction approximation holds or breaks down without relying on the knowledge of the accurate potential energy curves. [ABSTRACT FROM AUTHOR]

With a classical trajectory Monte Carlo model, we systematically study the laser intensity and field amplitude ratio dependence of nonsequential double ionization by counter-rotating two-color circularly polarized fields (800 and 1600 nm). The results show that the optimized field amplitude ratio changes with the laser intensity, which is attributed to the shift of the most probable amplitude ratio of electron returning with the laser intensity. Moreover, the laser intensity-dependent double ionization probability curve shows a remarkable dip in the transition region between the nonsequential and sequential channels. It can be well explained by the reduction of the probability of electron returning with the increase of the laser intensity. [ABSTRACT FROM AUTHOR]

The momentum distribution of photoelectrons in H2+ molecules subjected to an attosecond pulse is theoretically investigated. To better understand the laser–molecule interaction, we develop an in-line photoelectron holography approach that is analogous to optical holography. This approach is specifically suitable for extracting the amplitude and phase of the forward-scattered electron wave packet in a dissociating molecule with atomic precision. We also extend this approach to imaging the transient scattering cross-section of a molecule dressed by a near infrared laser field. This attosecond photoelectron holography sheds light on structural microscopy of dissociating molecules with high spatial-temporal resolution. [ABSTRACT FROM AUTHOR]

Light–matter interactions are usually described within the electric-dipole approximation, where the magnetic-field component and the spatial variation of the light electric field over the relevant electronic length scales are both ignored. Non-dipole effects in photoionization were revealed to be tiny from the infrared to the soft X-ray domains, and all non-dipole observations reported so far were limited to single-pulse, single-colour measurements. Here we advance attosecond time-resolved spectroscopy into the non-dipole interaction regime. Using a self-referenced attosecond photoelectron interferometry on helium atoms, we resolve the electron subcycle motion along the light propagation direction in the 15 pm range driven by the magnetic component of a near-infrared laser field. Furthermore, we measure a time delay of 15 ± 10 as between the electric-dipole and electric-quadrupole transitions by resolving the asymmetry of the photoelectron forward–backward yields with attosecond resolution. These fundamental findings are supported by ab initio calculations based on the non-dipole time-dependent Schrödinger equation. Using a self-referenced attosecond photoelectron interferometry on helium atoms, the electron subcycle motion along the light propagation direction is observed in the 15 pm range. A time delay of 15 ± 10 as between the electric-dipole and electric-quadrupole transitions is also revealed. [ABSTRACT FROM AUTHOR]

To prepare high-performance asphalt cold replacement liquids, a composite modification preparation process was used to synthesize a styrene–butadiene–styrene (SBS) block copolymer, styrene–butadiene–rubber (SBR) copolymer, and polyphosphate acid (PPA), erucamide/diesel/acrylic ester as surfactants/diluents/reinforcing agent respectively. These six were blended to prepare an asphalt cold replenishment liquid (ACRL), and its modification effect on base asphalt was studied using base asphalt as the control group. A comparative study was conducted on the high- and low-temperature rheological properties and microstructure. The modification mechanisms of high-temperature asphalt cold replenishment liquid (H-ACRL) and low-temperature asphalt cold replenishment liquid (L-ACRL) were studied through dynamic shear rheometry, bending beam rheometry, Fourier-transform infrared spectroscopy, fluorescence microscopy, and atomic force microscopy. The results showed that the optimal dosages of PPA/SBS/SBR in H-ACRL and L-ACRL were (1.2%/5%/3%) and (0.9%/4%/4%), respectively. Within the optimal dosage range, the particles in the cold replenishment fluid were uniformly dispersed in the asphalt to form a dense and continuous network. No new functional groups were generated during the preparation of H-ACRL and L-ACRL, showing that the modifiers (surfactants/diluents/reinforcing agent) were only physically blended with the asphalt. [ABSTRACT FROM AUTHOR]

A poly(toluidine blue) modified glassy carbon electrode (PTB/GCE) was prepared by two-step electropolymerization, and was used for the stripping voltammetric analysis of trace uranium for the first time. The results showed that the PTB modified electrode had higher sensitivity of uranium detection compared with the glassy carbon electrode, and the standard addition method was satisfactory for seawater, river water and tap water. The PTB/GCE can be used as a mercury-free electrode for the electrochemical detection of uranyl ions in the environmental water, which provides a new way for the rapid detection of trace uranium. [ABSTRACT FROM AUTHOR]

With the development of emerging information technology, the traditional management methods of marine fishes are slowly replaced by new methods due to high cost, time-consumption and inaccurate management. The update of marine fishes management technology is also a great help for the creation of smart cities. However, some new methods have been studied that are too specific, which are not applicable for the other marine fishes, and the accuracy of identification is generally low. Therefore, this paper proposes an ecological Internet of Things (IoT) framework, in which a lightweight Deep Neural Networks model is implemented as a image recognition model for marine fishes, which is recorded as Fish-CNN. In this study, multi-training and evaluation of Fish-CNN is accomplished, and the accuracy of the final classification can be fixed to 89.89%–99.83%. Moreover, the final evaluation compared with Rem-CNN, Linear Regression and Multilayer Perceptron also verify the stability and advantage of our method. [ABSTRACT FROM AUTHOR]

We theoretically investigate nonadiabatic effects in tunneling ionization of a hydrogen atom induced by a few-cycle elliptically polarized laser pulse. We find a deflection angle between the maximum of the photoelectron momentum distribution and the direction of the negative vector potential corresponding to the electric-field peak. This deflection angle mainly originates from the fact that the instant of the maximal ionization rate does not exactly correspond to the instant of the electric-field peak in the few-cycle elliptically polarized laser pulse, revealing an ionization time shift between those two instants. The ionization time shift is a result of the nonadiabatic effect induced by the envelope of the few-cycle elliptically polarized laser pulse, which disappears in a long-pulsed laser. Our study is useful for understanding attoclock experiments using few-cycle elliptically polarized laser pulses. [ABSTRACT FROM AUTHOR]

In industrial recirculating aquaculture systems (IRAS), the autonomous decision control of feeding strategies remains a practical concern. Conventionally, control schemes were established from data‐driven view, which fails to comprehensively perceive activity status of fishes. To deal with this issue, a deep vision sensing‐based fuzzy control scheme is proposed for smart feeding in IRAS. In the first stage, a deep learning‐based object detection model is introduced to capture two aspects features as the decision factors: residual bait and eating frequency. In the second stage, a fuzzy neural network model is formulated to calculate control decision strategies via fuzzy inference. And experiments on real‐world visual scenes are conducted to verify the proposal. [ABSTRACT FROM AUTHOR]

New insights are proposed into enhancing detection of uranyl ions (UO22+) by electropolymerization brilliant cresyl blue–modified glassy carbon electrode (PBCB/GCE). The mercury-free PBCB/GCE sensor was applied to determine UO22+ in water samples by differential pulse adsorptive stripping voltammetry (DPAdSV). The unique combination of the PBCB/GCE and DPAdSV significantly improves sensitivity due to the polymer of high electroactive area and fast electron transfer rate. The DPAdSV current using a 3 mm diameter PBCB/GCE was proportional to the UO22+ concentration in the range 2.0–90.0 μg·L−1 (− 0.113 V vs. SCE) with a detection limit of 0.650 μg·L−1, RSD = 3.1% (n = 10), and 4.5% reproducibility. In addition, the sensitivity for UO22+ determination was further improved at using an 1 mm diameter PBCB/GCE, which enhances the efficiency of UO22+ deposition due to its higher current density. The 1 mm diameter PBCB/GCE based on DPAdSV technique could be used to determine uranyl ions in the concentration range 0.20–2.0 μg·L−1 (− 0.113 V vs. SCE) with a detection limit of 0.067 μg·L−1, RSD = 5.7 % (n = 10) and 5.4% reproducibility. Hence, the PBCB/GCE is a suitable candidate to substitute the mercury electrode. [ABSTRACT FROM AUTHOR]

Herein, a novel strategy for sensitive determination of uranium in natural water was proposed using electropolymerization of Nile blue modified glassy carbon electrode (PNB/GCE) and differential pulse adsorptive stripping voltammetry (DPAdSV). The preparation of modified electrodes, electrolyte, reproducibility, and substance interferences was studied. The PNB/GCE were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and DPAdSV. The DPAdSV peak current was proportional to the concentration of uranium in the range of 0.30–100 μg·L−1 with the detection limit of 0.19 μg·L−1 and R2 = 0.997. Finally, the PNB/GCE was successfully applied to determination of uranium in natural water samples. [ABSTRACT FROM AUTHOR]

Coherent superposition of electronic states induces attosecond electron motion in molecules. We theoretically investigate the strong-field ionization of this superposition state by numerically solving the time-dependent Schrödinger equation. In the obtained photoelectron momentum distribution, an intriguing bifurcation structure appears in the strong-field holographic interference pattern. We demonstrate that this bifurcation structure directly provides complete information about the status of the transient wave function of the superposition state: the horizontal location of the bifurcation in the momentum distribution reveals the relative phase of the involved components of the superposition state and the vertical position indicates the relative coefficient. Thus, this bifurcation structure takes a snapshot of the transient electron wave packet of the superposition state and provides an intuitive way to monitor electron motion in molecules. [ABSTRACT FROM AUTHOR]

Radioactive iodine is severely hazardous to human health and the environment because of its high specific activity and environmental mobility. In this article, three covalent organic frameworks (COFs) (named as DbTd‐COF, DpTd‐COF, and DaTd‐COF) were prepared for the removal of iodine in both gas and solution states. The COFs were obtained by the solvothermal reaction of 1,3,5,7‐tetrakis (4‐formylphenyl) adamantane (TFPA) with benzidine, 2,5‐diaminopyridine, and p‐phenylenediamine, respectively. The obtained samples were characterized by SEM, FT‐IR, TGA, and nitrogen adsorption‐desorption analysis. The rigid linker of phenzyl chains helps to improve the stability of the polymer. DbTd‐COF and DaTd‐COF show excellent thermomechanical stability with a decomposition temperature of over 400 °C. DbTd‐COF and DaTd‐COF show good uptake capacities of 4.93 and 4.48 g g−1 for iodine vapor capture, respectively. DpTd‐COF shows a slightly smaller iodine uptake of 3.43 g g−1. XPS results indicated that iodine was captured in the form of its polyiodide anions. A better recyclability can be obtained after four cycle runs. In addition, DaTd‐COF shows good removal of iodine (concentration: 500 mg L−1) from cyclohexane solution with an adsorption capacity of 666.79 mg g−1. [ABSTRACT FROM AUTHOR]

The Jahn-Teller effect is an essential mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to directly image the onset of Jahn-Teller symmetry breaking remains unreached. Here we employ ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution and unambiguously image the ultrafast dynamics of Jahn-Teller deformations of CH 4 + cation in symmetry space. It is unraveled that the Jahn-Teller deformation from C3v to C2v geometries takes a characteristic time of 20 ± 7 fs for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C2v structure involving complex revival process of multiple vibrational pathways of the CH 4 + cation. The Jahn-Teller effect is the spontaneous symmetry breaking of the molecular structure caused by the coupling of electrons and nuclei. Here the authors use ultrafast Coulomb explosion imaging to map the evolution of the fundamental symmetry lowering process in photoionized methane within around 20fs. [ABSTRACT FROM AUTHOR]

Strong-field tunneling ionization is the first step for a broad class of phenomena in intense laser-atom/molecule interactions. Accurate information about the electron wave packet from strong-field tunneling ionization of atoms and molecules is of essential importance for understanding various tunneling ionization triggered processes. Here, we survey the property of the electron wave packet in tunneling ionization of molecules with a method based on strong-field photoelectron holography. By solving the time-dependent Schrödinger equation, it is shown that the holographic interference in the photoelectron momentum distribution exhibits the asymmetric behavior with respect to the laser polarization direction, when the molecule is aligned with a nonzero angle to the linearly polarized laser field. We demonstrate that this asymmetry is due to the nonzero initial transverse displacement of the electron wave packet at tunneling. By analyzing the holographic interference, this transverse displacement for the launching of electron wave packet tunneling from the molecules is accurately retrieved. This displacement is directly related to the electron density distribution in molecules, and thus our work developed a novel concept for probing electronic structure in molecules. [ABSTRACT FROM AUTHOR]

We use an interferometic scheme to extract the phase distribution of the electron wave packet from above-threshold ionization in elliptically polarized laser fields. In this scheme, an electron wave packet released from a circularly polarized laser pulse acts as a reference wave and interferes with the electron wave packet ionized by a time-delayed counter-rotating elliptically polarized laser field. The generated vortex-shaped interference pattern in the photoelectron momentum distribution enables us to extract the phase distribution of the electron wave packet in the elliptically polarized laser pulse with high precision. By artificially screening the ionic potential at different ranges when solving the time-dependent Schördinger equation, we find that the angle-dependent phase distribution of the electron wave packet in the elliptically polarized laser field shows an obvious angular shift as compared to the strong-field approximation, whose value is the same as the attoclock shift. We also show that the amplitude of the angle-dependent phase distribution is sensitive to the ellipticity of the laser pulse, providing an alternative way to precisely calibrate the laser ellipticity in the attoclock measurement. [ABSTRACT FROM AUTHOR]

By numerically solving the three-dimensional time-dependent Schrödinger equation, we theoretically investigate the dynamic interference of the hydrogen atom in intense arbitrarily polarized high-frequency XUV pulses with and without the non-dipole correction included. Our results show a clear shift of the dynamic-interference peaks in the photoelectron spectra from the linearly and circularly polarized XUV pulses, which can be attributed to the different AC Stark shifts of the ground state. The non-dipole correction for the electron–light interaction produces a similar peak shift along the propagation direction in the photoelectron momentum spectra for the linear and circular pulses. But no obvious non-dipole effect for the AC Stark shift of the ground state is identified for the light pulse with intensity around 1019 W cm−2. [ABSTRACT FROM AUTHOR]

Direct and rapid determination of trace amounts of uranium in natural water remains a challenge. Herein, determination of uranium by differential pulse adsorptive stripping voltammetry (DPAdSV) in presence of cupferron and diphenylguanidine on glassy carbon electrode was investigated. Under optimized conditions, the DPAdSV peak current was proportional to the concentration of uranium in the range of 3–80 μg L−1 with the detection limit of 1.0 μg L−1 and a linear correlation coefficient of 0.999. The DPAdSV method based on GCE was successfully applied to direct determination of trace uranium in natural water samples. [ABSTRACT FROM AUTHOR]

A novel permselective film of electrodeposited polydopamine (PDA) on electrochemical reduced graphene oxide (erGO) surface was prepared. The obtained composite films were characterized by atomic force microscope (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The influences of permselectivity with different electropolymerized cycles and concentration of dopamine on electrochemical responses of biomolecules on electrode were investigated. It was found that the composite film held high cationic permeable to dopamine (DA) and good suppression of ascorbic acid (AA) and uric acid (UA) using CV. The anodic peak currents were proportional to dopamine concentration. The significant permselectivity suggested that the PDA/graphene‐modified electrode has opened a new route to high selective dopamine biosensor. [ABSTRACT FROM AUTHOR]

This article takes Guangzhou as an example, the application of color pavement of bus lane has been studied technically, adopting research methods of internal analysis and field practice. At present, there are mainly three kinds of color pavement bus lanes in China, such as color asphalt pavement, ordinary color aggregate pavement and two-component color ceramic particles, by comparing and analyzing the performance of these three kinds of color pavement, combining with various factors such as the geographical characteristics of Guangzhou, it is considered that the two-component color ceramic particle color road surface is more suitable for the construction of Guangzhou bus lanes. The technical requirements for the setting of the color pavement bus lane were prepared, the application technology of the experiement section was introduced to provide reference for the similar project. [ABSTRACT FROM AUTHOR]

By numerically solving the two-dimensional time-dependent Schrödinger equation, we investigate the strong-field photoelectron holography (SFPH) for different atomic and molecular targets. The results show that the photoelectron hologram is capable of providing structural information-the phase of scattering amplitude. In our calculations, the holographic pattern shifts with the target, indicating the phase difference between various targets. However, for the near-forward scattering, the phases of scattering amplitude for different targets are similar and thus no structural information has been retrieved in the previous works on near-forward scattering hologram. We suggest to use the backward scattering photoelectron hologram to extract this type of structural information. This paves a significant step towards time-resolved imaging of molecular structure and dynamics with the concept of SFPH. [ABSTRACT FROM AUTHOR]

With the three-dimensional semiclassical ensemble model, we studied the correlated electron dynamics in strong-field nonsequential double ionization of Xe by mid-infrared laser pulses over a wide range of laser intensities. Numerical results show that the correlated electron momentum distribution exhibits the strong back-to-back pattern at the lower laser intensity. It evolves into the side-by-side behavior as the laser intensity increases and presents the experimentally observed crosslike shape at high laser intensity. Different from the case of near-infrared region where recollision mainly occurs at the first returning, at the mid-infrared region recollision dominantly occurs at the later returnings. The windows of initial transverse velocity for the various multiple-returning recollision trajectories are different and are unambiguously determined by this semiclassical ensemble model. [ABSTRACT FROM AUTHOR]

A modified model is established according to the analysis of energy balance acting on an agglomerate of binary mixed nanoparticles in a vibrated fluidized bed (VFB). The sizes of agglomerates of binary mixed nanoparticles are calculated with this model. The average agglomerate size estimated by the model of energy balance decreases with increasing superficial gas velocity. The vibration frequency had a comparatively significant impact on agglomerate sizes that seemed to change regularly and decreased with higher frequency. Both of the experimental and theoretical results showed that vibration led to a smaller agglomerate size, and the average agglomerate sizes calculated by this model provided the closest fit to those determined experimentally. [ABSTRACT FROM AUTHOR]

Better sensitivity and interface of ambient sampling/ionization mass spectrometry remain a challenge. Herein, a novel, plasma-based, ambient sampling/ionization/transmission (PASIT) integrated source in a pin-to-funnel configuration was developed for the sensitive analysis of complex samples. With the funnel sleeve directly affected by direct-current discharge plasma, PASIT combines the ability to sample/ionize analyte molecules and then efficiently collect/transport charged mass species under atmospheric pressure and consequently shows an improved sensitivity. The integrated source enhances the signal intensity by more than 2 orders of magnitude compared with the previous pin-to-plate plasma source without significant background addition. A surface limit of detection (LOD) of 130 fmol mm−2 (S/N = 3) has been achieved for clenbuterol on filter paper with an argon carrier gas. Demonstrated applications include the direct determination of active ingredients from drugs and symbolic compounds from natural plants and cholesterol from mouse brain tissue sections. [ABSTRACT FROM AUTHOR]

Using the classical ensemble method, we have investigated double ionization (DI) of stretched molecules by circularly polarized laser pulses. Back analysis of the DI trajectories shows that most DI occurs through a process of collision, indicating the nonsequential feature of DI. In contrast to the common recollision picture for nonsequential double ionization, here the first electron ionizes over the inner potential barrier of the molecule, moves directly towards the other nucleus and leads to excitation or ionization of the second electron by collision. The correlated momentum distributions for the electron pairs from this collision-induced nonsequential process show an obvious correlation pattern in the direction parallel to the molecular axis, whereas they show an anticorrelation pattern in the direction perpendicular to the molecular axis. [ABSTRACT FROM AUTHOR]

Chinese liquors are often a very important part of social event in China. Driven by high profit, some illegal traders often use inferior liquors instead of the products with high quality to cheat the customer. Therefore, it is highly required to authenticate Chinese liquors. In this paper a novel method based on ambient glow discharge ionization mass spectrometry has been developed to differentiate Chinese liquors. Volatile components from liquor samples were ionized by the plasma generated by glow discharge and then detected by a commercial linear ion trap mass spectrometer. Consequently, the fingerprint mass spectra of several Chinese liquors were obtained. Combined with principal component analysis, this new method was successfully applied to differentiate different brands of Chinese liquors without any sample pretreatment. Compared with conventional methods, this novel method has the advantages of easy operation, high speed, and high efficiency, which make it a potential tool in the fields of food safety, atmosphere chemistry. [ABSTRACT FROM AUTHOR]

Herbicides such as atrazine are widely used in the biosphere. Urine analysis is usually performed to evaluate the toxicological effects associated with atrazine exposure. A simple procedure based on the extractive electrospray ionization mass spectrometry (EESI-MS) method was established to detect atrazine and its metabolites in undiluted raw urine without sample pretreatment. A 4.3 × 10−14 g atrazine in spiked raw urine was detected and identified by EESI/MS/MS/MS. The detection limit was found to be 0.4 fg for atrazine (m/z 174) and 0.2 fg for 2-chloro-4, 6-diamino-S-triazine (DACT) (m/z 129) (S/N = 3) in EESI/MS/MS. A linear dynamic range of 4–5 orders of magnitude (r = 0.996) was determined for both atrazine and DACT. A single sample analysis was completed using tandem EESI-MS/MS within 1 min, providing a practical convenient method for rapid analysis of trace amounts of targeted metabolites present in complex matrices. Thus, tandem EESI-MS is potentially useful for previously discovered biomarker detection in multiple applications such as clinical diagnosis, drug discovery and forensic science. [ABSTRACT FROM AUTHOR]

Using the classical ensemble method, we have investigated double ionization (DI) of diatomic molecules driven by circularly polarized laser pulses with different internuclear distances (R). The results show that the DI mechanism changes from sequential double ionization (SDI) to nonsequential double ionization (NSDI) as the internuclear distance increases. In SDI range, the structure of the electron momentum distribution changes seriously as R increases, which indicates the sensitive dependence of the release times of the two electrons on R. For NSDI, because of the circular polarization, the ionization of the second electron is not through the well-known recollision process but through a process where the first electron ionizes over the inner potential barrier of the molecule, moves directly towards the other nucleus, and kicks out the second electron. [ABSTRACT FROM AUTHOR]

By numerically solving the time-dependent Schrödinger equation, we theoretically investigate the holographic structure of the multiple-returning rescattering recorded in the photoelectron momentum distribution. In the orthogonally polarized two-color fields, we show that the interference patterns periodically oscillate with the relative phase. Tracing the relative phase where the oscillation minimizes, we find that the dependences of the phase on the parallel momentum for the first-returning and the second-returning rescattering holographic interferences are different. With the quantum-orbit model, we demonstrated that the difference is related to the ionization and rescattering times of the electron. Moreover, we show that the influence of the Coulomb interaction on the oscillation of both the first-returning rescattering and the second-returning rescattering holographic interferences can be ignored. This suggests us that the temporal characteristics of the electron can be resolved by analyzing the relative phase's dependence of the multiple-returning holographic interference. [ABSTRACT FROM AUTHOR]

We calculate the photoelectron momentum distributions (PMDs) from strong-field above-threshold ionization of Ar in the co-linearly polarized two-color laser fields consisting a strong fundamental component and a much weaker second harmonic by solving the time-dependent Schrödinger equation. Utilizing the recently introduced phase-of-the-phase (PP) spectroscopy, we analyze the relative phase dependence of the PMDs of the recollision electrons and the jumps in the PP spectroscopy are observed. With the semi-classical model, we demonstrate that the phase jumps originate from the competition between the orbits where recollision occurs at different returnings. Thus, the relative contribution of the multiple-returning recollision orbits is unambiguously identified with the PP spectroscopy. Additionally, we show that the relative contribution of the multiple-returning recollision orbits depends on the laser wavelength and ellipticity. In elliptically polarized laser field, the yield of the high-energy photoelectrons favors the contribution of the second-returning recollision orbits. In 1600-nm laser field, the PP spectroscopy indicates that the relative contribution of multiple-returning recollision orbits is strongly sensitive to the electron energy. [ABSTRACT FROM AUTHOR]

The partition of the photon energy into the subsystems of molecules determines many photon-induced chemical and physical dynamics in laser-molecule interactions. The electron-nuclear energy sharing from multiphoton ionization of molecules has been used to uncover the correlated dynamics of the electron and fragments. However, most previous studies focus on symmetric molecules. Here we study the electron-nuclear energy sharing in strong-field photoionization of HeH2+ by solving the one-dimensional time-dependent Schrödinger equation (TDSE). Compared with symmetric molecules, the joint electron-nuclear energy spectrum (JES) of HeH2+ reveals an anomalous energy shift at certain nuclear energies, while it disappears at higher and lower nuclear energies. Through tracing the time evolution of the wavepacket of bound states, we identify that this energy shift originates from the joint effect of the Stark shift, associated with the permanent dipole, and the Autler-Townes effect due to the coupling of the 2pσ and 2sσ states in strong fields. The energy shift in the JES appears at certain nuclear distances only when both Stark effect and Autler-Townes effect play important roles. We further demonstrate that the electron-nuclei energy sharing can be controlled by varying laser intensity for asymmetric molecules, providing alternative approaches to manipulate photochemical reactions for more complex molecules. [ABSTRACT FROM AUTHOR]