Contents
2024
Volume: 4 Issue 1
9 Article(s)
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Research Articles
Reconstructing Molecular Orbitals with Laser-Induced Electron Tunneling Spectroscopy
XuanYang Lai, RenPing Sun, ShaoGang Yu, YanLan Wang, Wei Quan, André Staudte, and XiaoJun Liu
Photoelectron spectroscopy in intense laser fields has proven to be a powerful tool for providing detailed insights into molecular structure. The ionizing molecular orbital, however, has not been reconstructed from the photoelectron spectra, because its phase information is difficult to access. Here, we propose a methoPhotoelectron spectroscopy in intense laser fields has proven to be a powerful tool for providing detailed insights into molecular structure. The ionizing molecular orbital, however, has not been reconstructed from the photoelectron spectra, because its phase information is difficult to access. Here, we propose a method to retrieve the phase information of the ionizing molecular orbital. By analyzing the interference pattern in the photoelectron spectrum, the weighted coefficients and the relative phases of the constituent atomic orbitals for a molecular orbital can be extracted. With this information, we reconstruct the highest occupied molecular orbital of N2. Our work provides a reliable and straightforward approach for reconstructing molecular orbitals with the photoelectron spectroscopy..
Ultrafast Science
- Publication Date: Jan. 05, 2024
- Vol. 4, Issue 1, 0038 (2024)
Advances in Atomic Time Scale Imaging with a Fine Intrinsic Spatial Resolution
Jingzhen Li, Yi Cai, Xuanke Zeng, Xiaowei Lu, Qifan Zhu, and Yongle Zhu
Atomic time scale imaging, opening a new era for studying dynamics in microcosmos, is presently attracting immense research interest on the global level due to its powerful ability. On the atom level, physics, chemistry, and biology are identical for researching atom motion and atomic state change. The light possesses Atomic time scale imaging, opening a new era for studying dynamics in microcosmos, is presently attracting immense research interest on the global level due to its powerful ability. On the atom level, physics, chemistry, and biology are identical for researching atom motion and atomic state change. The light possesses twoness, the information carrier and the research resource. The most fundamental principle of this imaging is that light records the event-modulated light field by itself, so-called all-optical imaging. This paper can answer what is the essential standard to develop and evaluate atomic time scale imaging, what is the optimal imaging system, and what are the typical techniques to implement this imaging, up to now. At present, the best record in the experiment, made by multistage optical parametric amplification (MOPA), is realizing 50-fs resolved optical imaging with a spatial resolution of ~83 lp/mm at an effective framing rate of 15 × 1012 fps for recording an ultrafast optical lattice with its rotating speed up to 13.5 × 1012 rad/s..
Ultrafast Science
- Publication Date: Jan. 30, 2024
- Vol. 4, Issue 1, 0046 (2024)
Ultrafast Plasmonics for All-Optical Switching and Pulsed Lasers
Muhammad Aamir Iqbal, Wang Lin, Wang Pengyun, Jianrong Qiu, and Xiaofeng Liu
Surface plasmon resonances (SPRs) are often regarded as the collective oscillations of charge carriers localized at the dielectric–metal interface that display an ultrafast response upon light excitation. The recent developments in the fabrication and characterization of plasmonic nanostructures have stimulated continuSurface plasmon resonances (SPRs) are often regarded as the collective oscillations of charge carriers localized at the dielectric–metal interface that display an ultrafast response upon light excitation. The recent developments in the fabrication and characterization of plasmonic nanostructures have stimulated continuous effects in the search for their potential applications in the photonic fields. Concentrating on the role of plasmonics in photonics, this review covers recent advances in ultrafast plasmonic materials with a prime focus on all-optical switching. Fundamental phenomena of plasmonic light–matter interaction and plasmon dynamics are discussed by elaborating on the ultrafast processes unraveled by both experimental and theoretical methods, along with a comprehensive illustration of leveraging ultrafast plasmonics for all-optical switching and pulse laser generation with a focus on device design and performance. This review is concluded with a brief highlight of the current progress and the potential future directions in ultrafast plasmonics..
Ultrafast Science
- Publication Date: Mar. 14, 2024
- Vol. 4, Issue 1, 0048 (2024)
Multiple-Photon Resonance Enabled Quantum Interference in Emission Spectroscopy of N2+
Xiang Zhang, Qi Lu, YaLei Zhu, Jing Zhao, Rostyslav Danylo, Liang Xu, Mingwei Lei, Hongbing Jiang, Chengyin Wu, Zhedong Zhang, Aurélien Houard, Vladimir Tikhonchuk, André Mysyrowicz, Qihuang Gong, Songlin Zhuang, Zengxiu Zhao, and Yi Liu
Quantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with trQuantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter, regardless of how many optical frequencies are involved. Here, we report on quantum interference driven by multiple photons in the emission spectroscopy of nitrogen ions that are resonantly pumped by ultrafast infrared laser pulses. In the spectral domain, Fano resonance is observed in the emission spectrum, where a laser-assisted dynamic Stark effect creates the continuum. In the time domain, the fast-evolving emission is measured, revealing the nature of free-induction decay arising from quantum radiation and molecular cooperativity. These findings clarify the mechanism of coherent emission of nitrogen ions pumped with mid-infrared pump laser and are found to be universal. The present work opens a route to explore the important role of quantum interference during the interaction of intense laser pulses with materials near multiple photon resonance..
Ultrafast Science
- Publication Date: Jan. 05, 2024
- Vol. 4, Issue 1, 0051 (2024)
Metalens-Based Compressed Ultracompact Femtophotography: Analytical Modeling and Simulations
Miguel Marquez, Giacomo Balistreri, Roberto Morandotti, Luca Razzari, and Jinyang Liang
Single-shot 2-dimensional optical imaging of transient phenomena is indispensable for numerous areas of study. Among existing techniques, compressed ultrafast photography (CUP) using a chirped ultrashort pulse as active illumination can acquire nonrepetitive time-evolving events at hundreds of trillions of frames per sSingle-shot 2-dimensional optical imaging of transient phenomena is indispensable for numerous areas of study. Among existing techniques, compressed ultrafast photography (CUP) using a chirped ultrashort pulse as active illumination can acquire nonrepetitive time-evolving events at hundreds of trillions of frames per second. However, the bulky size and conventional configurations limit its reliability and application scopes. Superdispersive metalenses offer a promising solution for an ultracompact design with a stable performance by integrating the functions of a focusing lens and dispersive optical components into a single device. Nevertheless, existing metalens designs, typically optimized for the full visible spectrum with a relatively low spectral resolution, cannot be readily applied to active-illumination CUP. To address these limitations, here, we propose single-shot compressed ultracompact femtophotography (CUF) that synergically combines the fields of nanophotonics, optical imaging, compressed sensing, and deep learning. We develop the theory of CUF’s data acquisition composed of temporal–spectral mapping, spatial encoding, temporal shearing, and spatiotemporal integration. We also develop CUF’s image reconstruction via deep learning. Moreover, we design and evaluate CUF’s crucial components—a static binary transmissive mask, a superdispersive metalens, and a 2-dimensional sensor. Finally, using numerical simulations, CUF’s feasibility is verified using 2 synthetic scenes: an ultrafast beam sweeping across a surface and the propagation of a terahertz Cherenkov wave..
Ultrafast Science
- Publication Date: Jan. 09, 2024
- Vol. 4, Issue 1, 0052 (2024)
Two-Dimensional Control of Rydberg Fragment Emission in Dissociative Frustrated Ionization of Oxygen
Junyang Ma, Yongzhe Ma, Pengzhao Wang, Fan Yang, Lei Xiong, Yan Yang, Hongcheng Ni, Jian Wu, and Zhenrong Sun
Advances in producing tailored ultrashort laser pulses have enabled the generation and control of molecular dissociative Rydberg excitation along the polarization axis of the laser field. Here, we exploit the orthogonally polarized two-color femtosecond laser fields and achieve an unprecedented two-dimensional control Advances in producing tailored ultrashort laser pulses have enabled the generation and control of molecular dissociative Rydberg excitation along the polarization axis of the laser field. Here, we exploit the orthogonally polarized two-color femtosecond laser fields and achieve an unprecedented two-dimensional control of Rydberg fragment emission in the dissociative frustrated single ionization of oxygen. The Rydberg fragments are collected over the 4π solid angle, whose momentum distribution is manifested in a characteristic four-lobe pattern. Through precise scanning of the relative phase of the orthogonal two-color laser fields, we demonstrate control over asymmetric directional emission of the Rydberg fragments. Our experimental findings are well supported by classical trajectory Monte Carlo simulations, which suggest an efficient emission control achieved through the manipulation of charge localization upon ionization..
Ultrafast Science
- Publication Date: Feb. 08, 2024
- Vol. 4, Issue 1, 0053 (2024)
The Space-Charge Problem in Ultrafast Diagnostics: An All-Optical Solution for Streak Cameras
Vassily Kornienko, Yupan Bao, Joakim Bood, Andreas Ehn, and Elias Kristensson
The field of ultrafast science is dependent on either ultrashort laser pulse technology or ultrafast passive detection. While there exists a plethora of sub-picosecond laser pulse solutions, streak cameras are singular in providing sub-picosecond passive imaging capabilities. Therefore, their use in fields ranging fromThe field of ultrafast science is dependent on either ultrashort laser pulse technology or ultrafast passive detection. While there exists a plethora of sub-picosecond laser pulse solutions, streak cameras are singular in providing sub-picosecond passive imaging capabilities. Therefore, their use in fields ranging from medicine to physics is prevalent. Streak cameras attain such temporal resolutions by converting signal photons to electrons. However, the Coulomb repulsion force spreads these electrons spatiotemporally aggravating streak cameras’ temporal resolution and dynamic range—an effect that increases in severity in ultrafast applications where electrons are generated nearly instantaneously. While many electro-optical solutions have been proposed and successfully implemented, this issue remains as a challenge for all sub-picosecond streak camera technology. Instead of resorting to electro-optical solutions, in this work, we present an all-optical approach based on the combination of photon tagging and spatial lock-in detection with a technique called periodic shadowing—that is directly applicable to all generations of streak cameras. We have demonstrated that this accessible all-optical solution, consisting of a single externally applied optical component, results in (a) a >3× improvement in dynamic range, (b) a 25% increase in temporal resolution, and (c) a reduction of background noise levels by a factor of 50, which, when combined, allows for a markedly improved accuracy in the measurement of ultrafast signals..
Ultrafast Science
- Publication Date: Jan. 30, 2024
- Vol. 4, Issue 1, 0055 (2024)
Aggregation Regulated Ultrafast Singlet Fission Pathways in TIPS-Pentacene Films
Guang Huang, Junzi Li, Zilin Zhou, Zongtao Huang, Wei Kong, Fangteng Zhang, Youjun Zeng, Guanyu Liu, Tingchao He, and Lin Ma
Singlet fission (SF) is a spin-conserving process converting 1 singlet exciton into 2 triplet excitons. This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley–Queisser limit. However, it remains unclear how intermolecular coupling, which is subject tSinglet fission (SF) is a spin-conserving process converting 1 singlet exciton into 2 triplet excitons. This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley–Queisser limit. However, it remains unclear how intermolecular coupling, which is subject to the aggregation extent in thin-film morphology, controls SF pathways and dynamics. The prototype molecule 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) has been extensively studied to investigate SF mechanisms. However, previous literature reports have presented divergent SF mechanisms and pathways in TIPS-pentacene films. In this study, solvent vapor annealing treatment is used to deliberately adjust the aggregation extent in TIPS-pentacene films. This enables us to reproduce various SF pathways reported in the literature under the same experimental conditions, with the only variation being the level of aggregation. These results shed light on the crucial role that molecular aggregation plays in modulating both the SF mechanism and pathway and reconciles the previously contentious SF mechanisms and pathways reported in TIPS-pentacene films. Our study offers substantial insights into the understanding of the SF mechanism and provides a potential avenue for future control of SF pathways in accordance with specific application requirements..
Ultrafast Science
- Publication Date: Feb. 16, 2024
- Vol. 4, Issue 1, 0057 (2024)
Ultrafast, Single-Event Ptychographic Imaging of Transient Electron Dynamics
Jonathan Barolak, David Goldberger, Bojana Ivanic, David Schmidt, Claudia A. M. Schrama, Charles G. Durfee, and Daniel E. Adams
Dynamic phenomena occurring on the ultrafast time scales are inherently difficult to image. While pump–probe techniques have been used for decades, probing nonrepeatable phenomena precludes this form of imaging. Additionally, many ultrafast phenomena, such as electron dynamics, exhibit low amplitude contrast in the optDynamic phenomena occurring on the ultrafast time scales are inherently difficult to image. While pump–probe techniques have been used for decades, probing nonrepeatable phenomena precludes this form of imaging. Additionally, many ultrafast phenomena, such as electron dynamics, exhibit low amplitude contrast in the optical wavelength range and thus require quantitative phase imaging. To better understand the underlying physics involved in a plethora of ultrafast phenomena, advanced imaging techniques must be developed to observe single events at an ultrafast time scale. Here, we present, to the best of our knowledge, the first ptychographic imaging system capable of observing ultrafast dynamics from a single event. We demonstrate ultrafast dynamic imaging by observing the conduction band electron population from a 2-photon absorption event in ZnSe pumped by a single femtosecond pulse. We verify experimental observations by comparing them to numeric solutions of a nonlinear envelope equation. Our imaging method represents a major step forward in ultrafast imaging, bringing the capabilities of ptychography to the ultrafast regime..
Ultrafast Science
- Publication Date: Feb. 22, 2024
- Vol. 4, Issue 1, 0058 (2024)
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