scholarly journals Realization of a Continuously Phase-Locked Few-Cycle Deep-UV/XUV Pump-Probe Beamline with Attosecond Precision for Ultrafast Spectroscopy

2021 ◽  
Vol 11 (15) ◽  
pp. 6840
Author(s):  
Tsendsuren Khurelbaatar ◽  
Alexander Gliserin ◽  
Je-Hoi Mun ◽  
Jaeuk Heo ◽  
Yunman Lee ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Extreme Ultraviolet ◽  
High Temporal Resolution ◽  
Electron Dynamics ◽  
Nuclear Dynamics ◽  
Pump And Probe ◽  
Active Stabilization ◽  
Continuous Time Delay ◽  
Deep Uv

Chemical and physical processes in molecules can be controlled through the manipulation of quantum interferences between rotational, vibrational, and electronic degrees of freedom. Most of the past efforts have been focused on the control of nuclear dynamics. Even though electronic coherence and its coupling to nuclear degrees of freedom may profoundly affect the outcome of these processes, electron dynamics have received less attention. Proper investigation of electron dynamics in materials demands ultrafast sources in the visible, ultraviolet (UV), and extreme ultraviolet (XUV) spectral region. For this purpose, a few-cycle deep-UV and XUV beamlines have been constructed for studying ultrafast electron dynamics in molecules. To ensure the required high temporal resolution on the attosecond time scale, vibration isolation from environmental mechanical noise and active stabilization have been implemented to achieve attosecond timing control between pump and probe pulses with excellent stability. This is achieved with an actively phase-stabilized double-layer Mach-Zehnder interferometer system capable of continuous time-delay scans over a range of 200 fs with a root-mean-square timing jitter of only 13 as over a few seconds and ~80 as of peak-to-peak drift over several hours.

scholarly journals Photo-Induced Coupled Nuclear and Electron Dynamics in the Nucleobase Uracil

2021 ◽  
Vol 9 ◽  
Author(s):  
Lena Bäuml ◽  
Thomas Schnappinger ◽  
Matthias F. Kling ◽  
Regina de Vivie-Riedle
Keyword(s):  
Laser Pulse ◽  
Degrees Of Freedom ◽  
Relaxation Mechanism ◽  
Electron Dynamics ◽  
Nuclear Dynamics ◽  
Molecular Systems ◽  
Ultrafast Relaxation ◽  
Long Time ◽  
Fast Electronic ◽  
Ultrashort Laser

Photo-initiated processes in molecules often involve complex situations where the induced dynamics is characterized by the interplay of nuclear and electronic degrees of freedom. The interaction of the molecule with an ultrashort laser pulse or the coupling at a conical intersection (CoIn) induces coherent electron dynamics which is subsequently modified by the nuclear motion. The nuclear dynamics typically leads to a fast electronic decoherence but also, depending on the system, enables the reappearance of the coherent electron dynamics. We study this situation for the photo-induced nuclear and electron dynamics in the nucleobase uracil. The simulations are performed with our ansatz for the coupled description of the nuclear and electron dynamics in molecular systems (NEMol). After photo-excitation uracil exhibits an ultrafast relaxation mechanism mediated by CoIn's. Both processes, the excitation by a laser pulse and the non-adiabatic relaxation, are explicitly simulated and the coherent electron dynamics is monitored using our quantum mechanical NEMol approach. The electronic coherence induced by the CoIn is observable for a long time scale due to the delocalized nature of the nuclear wavepacket.

scholarly journals Control of nuclear dynamics in the benzene cation by electronic wavepacket composition

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Thierry Tran ◽  
Graham A. Worth ◽  
Michael A. Robb
Keyword(s):  
Extreme Ultraviolet ◽  
Initial Conditions ◽  
Chemical Reactivity ◽  
Electronic States ◽  
Time Dependent ◽  
Electronic Control ◽  
Electron Dynamics ◽  
Nuclear Dynamics ◽  
Successive Passage ◽  
Dynamics Simulations

AbstractThe study of coupled electron-nuclear dynamics driven by coherent superpositions of electronic states is now possible in attosecond science experiments. The objective is to understand the electronic control of chemical reactivity. In this work we report coherent 8-state non-adiabatic electron-nuclear dynamics simulations of the benzene radical cation. The computations were inspired by the extreme ultraviolet (XUV) experimental results in which all 8 electronic states were prepared with significant population. Our objective was to study the nuclear dynamics using various bespoke coherent electronic state superpositions as initial conditions in the Quantum-Ehrenfest method. The original XUV measurements were supported by Multi-configuration time-dependent Hartree (MCTDH) simulations, which suggested a model of successive passage through conical intersections. The present computations support a complementary model where non-adiabatic events are seen far from a conical intersection and are controlled by electron dynamics involving non-adjacent adiabatic states. It proves to be possible to identify two superpositions that can be linked with two possible fragmentation paths.

Introduction

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
Degrees Of Freedom ◽  
State Level ◽  
Boltzmann Distribution ◽  
Theoretical Description ◽  
Time Dependent ◽  
Nuclear Dynamics ◽  
Molecular Reaction ◽  
Oppenheimer Approximation

This introductory chapter considers first the relation between molecular reaction dynamics and the major branches of physical chemistry. The concept of elementary chemical reactions at the quantized state-to-state level is discussed. The theoretical description of these reactions based on the time-dependent Schrödinger equation and the Born–Oppenheimer approximation is introduced and the resulting time-dependent Schrödinger equation describing the nuclear dynamics is discussed. The chapter concludes with a brief discussion of matter at thermal equilibrium, focusing at the Boltzmann distribution. Thus, the Boltzmann distribution for vibrational, rotational, and translational degrees of freedom is discussed and illustrated.

scholarly journals Opto-Mechanical Inertial Sensors (OMIS) for High Temporal Resolution Gravimetry

2020 ◽  
Author(s):  
Lee Kumanchik ◽  
Felipe Guzman ◽  
Claus Braxmaier
Keyword(s):  
High Frequency ◽  
High Stability ◽  
Vibration Isolation ◽  
Inertial Sensors ◽  
Response Times ◽  
Free Spectral Range ◽  
Optical Cavity ◽  
Fused Silica ◽  
High Temporal Resolution ◽  
Free Falling

<p>Gravity field measurement by free-falling atoms has the potential for very high stability<br>over time as the measurement exposes a direct, fundamental relationship between mass<br>and acceleration. However, the measurement rate of the current state-of-the-art limits<br>the performance at short timescales (greater than 1 Hz). Classical inertial sensors operate<br>at much faster response times and are thus natural companions for free-falling atom<br>sensors. Such a hybrid device would gain the ultra-high stability of the free-falling atom<br>sensor while greatly extending the bandwidth to higher frequency using the classical<br>sensor. This requires the stable bandwidth of both devices to overlap sufficiently. We<br>have developed opto-mechanical inertial sensors (OMIS) with good long term stability for<br>just this purpose. The sensors are made of highly stable fused silica material, feature a<br>monolithic optical cavity for displacement readout, and utilize a laser diode stabilized to<br>a molecular reference. With no temperature control and only the thermal shielding<br>provided by the vacuum chamber, this device is stable down to 0.1 Hz which overlaps<br>with the bandwidth of free-falling atom sensors. The OMIS are self-calibrating by<br>converting the fundamental resonances of a molecular gas into length using the<br>free-spectral range of the optical cavity,  <em>FSR = c/2nL</em>,  and then sampling the OMIS<br>mechanical damping rate and resonance frequency using a nearby piezo. This<br>acceleration calibration is potentially transferable to a companion free-falling atom<br>sensor. Readout is performed by modulating the cavity length of the OMIS with one<br>cavity mirror being the OMIS itself and the other being a high frequency resonator. The<br>high frequency resonator is driven by a nearby piezo well above the response rate of the<br>OMIS and acts like an ultrastable quartz clock. The resulting highly stable tone is<br>demodulated by the readout electronics. For the low finesse optical cavity used here, this<br>yields a displacement resolution of 2x10<sup>-13</sup> m/√Hz and a high frequency acceleration<br>resolution of 400 n<em>g</em> /√Hz. At 0.1 Hz the acceleration resolution is 1.5 μ<em>g</em> /√Hz limited by<br>the stability of our vibration isolation stage. The OMIS dimensions are about 30 mm x 30<br>mm x 5 mm and can be fiber coupled to enable co-location with other sensors or as<br>standalone devices for future gravimetry both on Earth and in space</p>

Introduction To Solids And Their Interfaces

2006 ◽  
Author(s):  
Abraham Nitzan
Keyword(s):  
Cell Volume ◽  
Atomic Structure ◽  
Degrees Of Freedom ◽  
Molecular System ◽  
Lattice Points ◽  
Condensed Phases ◽  
Nuclear Dynamics ◽  
Densities Of States ◽  
Unit Cells ◽  
Comprehensive Discussion

The study of dynamics of molecular processes in condensed phases necessarily involves properties of the condensed environment that surrounds the system under consideration. This chapter provides some essential background on the properties of solids while the next chapter does the same for liquids. No attempt is made to provide a comprehensive discussion of these subjects. Rather, this chapter only aims to provide enough background as needed in later chapters in order to take into consideration two essential attributes of the solid environment: Its interaction with the molecular system of interest and the relevant timescales associated with this interaction. This would entail the need to have some familiarity with the relevant degrees of freedom, the nature of their interaction with a guest molecule, the corresponding densities of states or modes, and the associated characteristic timescales. Focusing on the solid crystal environment we thus need to have some understanding of its electronic and nuclear dynamics. The geometry of a crystal is defined with respect to a given lattice by picturing the crystal as made of periodically repeating unit cells. The atomic structure within the cell is a property of the particular structure (e.g. each cell can contain one or more molecules, or several atoms arranged within the cell volume in some given way), however, the cells themselves are assigned to lattice points that determine the periodicity. This periodicity is characterized by three lattice vectors, ai, i = 1, 2, 3, that determine the primitive lattice cell—a parallelepiped defined by these three vectors.

scholarly journals Active stabilization of unmanned aerial vehicle imaging platform

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1791-1803 ◽  
Author(s):  
Mohit Verma ◽  
Vicente Lafarga ◽  
Mael Baron ◽  
Christophe Collette
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Unmanned Aerial Vehicle ◽  
Vibration Isolation ◽  
Isolation System ◽  
Aerial Vehicles ◽  
Active Stabilization ◽  
Aerial Vehicle ◽  
Active Vibration ◽  
Improved Performance

The advancement in technology has seen a rapid increase in the use of unmanned aerial vehicles for various applications. These unmanned aerial vehicles are often equipped with the imaging platform like a camera. During the unmanned aerial vehicle flight, the camera is subjected to vibrations which hamper the quality of the captured images/videos. The high-frequency vibrations from the unmanned aerial vehicle are transmitted to the camera. Conventionally, passive rubber mounts are used to isolate the camera from the drone vibrations. The passive mounts are able to provide reduction in response near the resonance. However, this comes at the cost of amplification of response at the higher frequency. This article proposes an active vibration isolation system which exhibits improved performance at the higher frequencies than the conventional system. The active isolation system consists of a contact-less voice coil actuator supported by four springs. Experiments are carried out to study the effect of vibrations on the quality of images captured. The characterization of drone vibrations is also carried out by recording the acceleration during different flight modes. The performance of the proposed isolation system is experimentally validated on a real drone camera subjected to the recorded drone acceleration spectrum. The isolation system is found to perform better than the conventional rubber mounts and is able to reduce the vibrations to a factor of one-fourth. It can be effectively used to improve the image acquisition quality of the unmanned aerial vehicles.

Theory and Method of Dynamic Modeling for Multilayer Vibration Isolation System

2000 ◽  
Author(s):  
Liao Dao-Xun ◽  
Lu Yong-Zhong ◽  
Huang Xiao-Cheng
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Vibration Isolation ◽  
Rigid Bodies ◽  
Design Calculation ◽  
Isolation System ◽  
Dry Land ◽  
Vibration Isolation System ◽  
Six Degrees Of Freedom ◽  
Floating Raft

Abstract The multilayer vibration isolation system has been widely applied to isolate vibration in dynamic devices of ships, high-speed vehicles forging hammer and precise instruments. The paper is based on the coordinate transformation of space general motion for mass blocks (rigid bodies) and Lagrangian equation of multilayer vibration isolation system. It gives a strict mathematical derivation on the differential equation of the motion for the system with six degrees of freedom of relative motion between mass blocks (including base). The equations are different from the same kind of equations in the reference literatures. It can be used in the floating raft of ships in order to isolates vibration and decrease noise, also used in design calculation of the multilayer vibration isolation for dynamic machines and precise instruments on the dry land.

scholarly journals Attosecond Streaking Time Delays: Finite-Range Interpretation and Applications

2019 ◽  
Vol 9 (3) ◽  
pp. 492 ◽  
Author(s):  
Cory Goldsmith ◽  
Agnieszka Jaroń-Becker ◽  
Andreas Becker
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Extreme Ultraviolet ◽  
Theoretical Studies ◽  
Half Cycle ◽  
Finite Range ◽  
Electron Dynamics ◽  
The Continuum

We review theoretical studies of the attosecond streaking time delay concept in photoionization via the investigation of the electron dynamics in the streaking field after the transition of the photoelectron into the continuum upon absorption of an extreme ultraviolet photon. Based on the results, a so-called finite range interpretation was introduced, which highlighted that the delay is accumulated until the streaking pulse ends and, hence, over a finite range of the potential of the parent ion. Following a discussion of the analysis leading to this interpretation, we summarize a few applications which provide insights into different aspects of the streaking time delay concept in photoionization. Besides a review of previously presented results, we give an analysis of the relevance of the first half-cycle of the streaking field and an outlook regarding the perspective of using the streaking method to resolve dynamical changes in the potential that the photoelectron explores during its propagation in the continuum.

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