Optimal control of femtosecond multiphoton double ionization of atomic calcium

Papastathopoulos, Evangelos; Strehle, M.; Gerber, G.

doi:10.1016/j.cplett.2005.04.001

Cited by 27 publications

(23 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[118,119] We used adaptive femtosecond pulse shaping to address the question of double ionization in atomic calcium. [120] Alkaline earth atoms are attractive systems in this context because they have lower ionization thresholds than noble gases, and a manifold of doubly excited states are embedded in the ionic continuum between the first and second ionization threshold. These states can serve as intermediate resonances in multiphoton ionization, and the adaptive technique can explore a large number of potential excitation pathways.…”

Section: Atomic Multiphoton Ionizationmentioning

confidence: 99%

“…Double ionization is increased by reducing the contribution from sequential ionization and enhancing the contribution from nonsequential electron emission. [120] For this purpose, we employed adaptive learning control to maximize the Ca 2 yield. The situation for the Ca and the Ca 2 ion yields before optimization is shown in Figure 11 a (left).…”

Section: Atomic Multiphoton Ionizationmentioning

confidence: 99%

“…[120] This technique should also be applicable to large molecules, giving more detailed information about the ensuing wavepacket dynamics and even allowing control over structural changes such as, for example, in photoisomerization reactions.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Quantum Control of Gas‐Phase and Liquid‐Phase Femtochemistry

Brixner¹,

Gerber²

2003

ChemPhysChem

370

288

View full text Add to dashboard Cite

Active control of chemical reactions on a microscopic (molecular) level, that is, the selective breaking or making of chemical bonds, is an old dream. However, conventional control agents used in chemical synthesis are macroscopic variables such as temperature, pressure or concentration, which gives no direct access to the quantum-mechanical reaction pathway. In quantum control, by contrast, molecular dynamics are guided with specifically designed light fields. Thus it is possible to efficiently and selectively reach user-defined reaction channels. In the last years, experimental techniques were developed by which many breakthroughs in this field were achieved. Femtosecond laser pulses are manipulated in so-called pulse shapers to generate electric field profiles which are specifically adapted to a given quantum system and control objective. The search for optimal fields is guided by an automated learning loop, which employs direct feedback from experimental output. Thereby quantum control over gas-phase as well as liquid-phase femtochemical processes has become possible. In this review, we first discuss the theoretical and experimental background for many of the recent experiments treated in the literature. Examples from our own research are then used to illustrate several fundamental and practical aspects in gas-phase as well as liquid-phase quantum control. Some additional technological applications and developments are also described, such as the automated optimization of the output from commercial femtosecond laser systems, or the control over the polarization state of light on an ultrashort timescale. The increasing number of successful implementations of adaptive learning techniques points at the great versatility of computer-guided optimization methods. The general approach to active control of light-matter interaction has also applications in many other areas of modern physics and related disciplines.

show abstract

Section: Atomic Multiphoton Ionizationmentioning

confidence: 99%

Section: Atomic Multiphoton Ionizationmentioning

confidence: 99%

See 1 more Smart Citation

Quantum Control of Gas‐Phase and Liquid‐Phase Femtochemistry

Brixner¹,

Gerber²

2003

ChemPhysChem

370

288

View full text Add to dashboard Cite

show abstract

“…Pulse trains have been used for coherent control of a diverse array of processes, such as photoelectron angular distributions [16,17], magnetization [18], and molecular vibration and rotation [19]. At the same time, they have appeared in optimal-pulse solutions in control experiments * dbfoote@umd.edu † wth@umd.edu [15,[20][21][22][23]. Deconstruction of these pulses, to determine how they achieve their goals, has proven to be a difficult and arduous task.…”

Section: Introductionmentioning

confidence: 99%

Ionization enhancement and suppression by phase-locked ultrafast pulse pairs

Foote

Lin

et al. 2017

Phys. Rev. A

View full text Add to dashboard Cite

We present the results of a study of ionization of Xe atoms by a pair of phase-locked pulses, which is characterized by interference produced by the twin peaks. Two types of interference are considered: ordinary optical interference, which changes the intensity of the composite pulse and thus the ion yield, and a quantum interference, in which the excited electron wave packets interfere. We use the measured Xe + yield as a function of the temporal delay and/or relative phase between the peaks to monitor the interferences and compare their relative strengths. We model the interference with a pulse intensity function and by calculating the ionization yield with the time-dependent Schrödinger equation. Our results provide insight into optimal control pulses generated with learning algorithms. The results also show that the relative phase between peaks of a control pulse, along with small features such as distortions and imperfections in the wings of an ideal shape, play a significant role in the control process.

show abstract

“…The spatial pulse shaping is required to control the composition of the plume and to achieve the fully atomized gas phase by a single subpicosecond laser pulse (Gamaly et al, 2007). Temporally shaping of ultrashort laser pulses by Fourier synthesis of the spectral components is an effective technique to control numerous physical and chemical processes (Assion et al, 1998), like: the control of ionization processes (Papastathopoulos et al, 2005), the improvement of high harmonic soft X-Rays emission efficiency (Bartels et al, 2000), materials processing (Stoian et al, 2003;Jegenyes et al, 2006;Ristoscu et al, 2006) and spectroscopic applications (Assion et al, 2003;Gunaratne et al, 2006). The adaptive pulse shaping has been applied for ion ejection efficiency (Colombier et al, 2006;Dachraoui and Husinsky, 2006), generation of nanoparticles with tailored size (Hergenroder et al, 2006), applications in spectroscopy and pulse characterization (Ackermann et al, 2006;Lozovoy et al, 2008).…”

mentioning

confidence: 99%