scholarly journals Pulse duration effect on photoelectron spectrum of atom irradiated by strong high frequency laser

2018 ◽  
Vol 67 (7) ◽  
pp. 073202
Author(s):  
Guo Jing ◽  
Guo Fu-Ming ◽  
Chen Ji-Gen ◽  
Yang Yu-Jun
Keyword(s):  
Pulse Duration ◽  
High Frequency ◽  
Photoelectron Spectrum ◽  
Frequency Laser ◽  
Duration Effect

Lead Extraction with High-Frequency Laser Sheaths: A Single-Center Experience

2016 ◽  
Vol 64 (S 01) ◽  
Author(s):  
M. Linder ◽  
S. Pecha ◽  
S. Zipfel ◽  
L. Castro ◽  
N. Gosau ◽  
...  
Keyword(s):  
High Frequency ◽  
Lead Extraction ◽  
Single Center ◽  
Single Center Experience ◽  
Frequency Laser

scholarly journals Circular Rydberg states of helium atoms or helium-like ions in a high-frequency laser field

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 11-17
Author(s):  
Nikolay Kryukov ◽  
Eugene Oks
Keyword(s):  
High Frequency ◽  
Laser Field ◽  
Nuclear Charge ◽  
Rydberg States ◽  
Orbital Plane ◽  
Precession Frequency ◽  
Nonmonotonic Dependence ◽  
Absolute Value ◽  
Rydberg Electron ◽  
Frequency Laser

Abstract In the literature, there were studies of Rydberg states of hydrogenic atoms/ions in a high-frequency laser field. It was shown that the motion of the Rydberg electron is analogous to the motion of a satellite around an oblate planet (for a linearly polarized laser field) or around a (fictitious) prolate planet (for a circularly polarized laser field): it exhibits two kinds of precession – one of them is the precession within the orbital plane and another one is the precession of the orbital plane. In this study, we study a helium atom or a helium-like ion with one of the two electrons in a Rydberg state, the system being under a high-frequency laser field. For obtaining analytical results, we use the generalized method of the effective potentials. We find two primary effects of the high-frequency laser field on circular Rydberg states. The first effect is the precession of the orbital plane of the Rydberg electron. We calculate analytically the precession frequency and show that it differs from the case of a hydrogenic atom/ion. In the radiation spectrum, this precession would manifest as satellites separated from the spectral line at the Kepler frequency by multiples of the precession frequency. The second effect is a shift of the energy of the Rydberg electron, also calculated analytically. We find that the absolute value of the shift increases monotonically as the unperturbed binding energy of the Rydberg electron increases. We also find that the shift has a nonmonotonic dependence on the nuclear charge Z: as Z increases, the absolute value of the shift first increases, then reaches a maximum, and then decreases. The nonmonotonic dependence of the laser field-caused energy shift on the nuclear charge is a counterintuitive result.

scholarly journals Effect of Pulse Duration and Direction on Plasticity Induced by 5 Hz Repetitive Transcranial Magnetic Stimulation in Correlation With Neuronal Depolarization

2021 ◽  
Vol 15 ◽  
Author(s):  
Islam Halawa ◽  
Katharina Reichert ◽  
Aman S. Aberra ◽  
Martin Sommer ◽  
Angel V. Peterchev ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Pulse Duration ◽  
High Frequency ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Time Constants ◽  
Resting Motor Threshold

Introduction: High frequency repetitive transcranial magnetic stimulation applied to the motor cortex causes an increase in the amplitude of motor evoked potentials (MEPs) that persists after stimulation. Here, we focus on the aftereffects generated by high frequency controllable pulse TMS (cTMS) with different directions, intensities, and pulse durations.Objectives: To investigate the influence of pulse duration, direction, and amplitude in correlation to induced depolarization on the excitatory plastic aftereffects of 5 Hz repetitive transcranial magnetic stimulation (rTMS) using bidirectional cTMS pulses.Methods: We stimulated the hand motor cortex with 5 Hz rTMS applying 1,200 bidirectional pulses with the main component durations of 80, 100, and 120 μs using a controllable pulse stimulator TMS (cTMS). Fourteen healthy subjects were investigated in nine sessions with 80% resting motor threshold (RMT) for posterior-anterior (PA) and 80 and 90% RMT anterior-posterior (AP) induced current direction. We used a model approximating neuronal membranes as a linear first order low-pass filter to estimate the strength–duration time constant and to simulate the membrane polarization produced by each waveform.Results: PA and AP 5 Hz rTMS at 80% RMT produced no significant excitation. An exploratory analysis indicated that 90% RMT AP stimulation with 100 and 120 μs pulses but not 80 μs pulses led to significant excitation. We found a positive correlation between the plastic outcome of each session and the simulated peak neural membrane depolarization for time constants >100 μs. This correlation was strongest for neural elements that are depolarized by the main phase of the AP pulse, suggesting the effects were dependent on pulse direction.Conclusions: Among the tested conditions, only 5 Hz rTMS with higher intensity and wider pulses appeared to produce excitatory aftereffects. This correlated with the greater depolarization of neural elements with time constants slower than the directly activated neural elements responsible for producing the motor output (e.g., somatic or dendritic membrane).Significance: Higher intensities and wider pulses seem to be more efficient in inducing excitation. If confirmed, this observation could lead to better results in future clinical studies performed with wider pulses.

Effect of the High-Frequency Laser Radiation on the Nonlinear Optical Properties of n-Type Double δ-Doped GaAs Quantum Wells

2019 ◽  
Vol 19 (7) ◽  
pp. 4167-4171
Author(s):  
Fatih Ungan ◽  
Huseyin Sari ◽  
Esin Kasapoglu ◽  
Unal Yesilgul ◽  
Serpil Sakiroglu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Quantum Wells ◽  
High Frequency ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Frequency Laser

Single-Axis Projection Scheme for Conducting Sequential Lateral Solidifica-tion of Si Films for Large-Area Electronics

2001 ◽  
Vol 685 ◽  
Author(s):  
Alexander Limanov ◽  
Vladimir Borisov
Keyword(s):  
Pulse Duration ◽  
High Frequency ◽  
Excimer Lasers ◽  
Melting Line ◽  
Large Area ◽  
Technical Challenge ◽  
Projection Scheme ◽  
Different Types ◽  
Si Films ◽  
Projection Optics

AbstractThis paper deals with some results of research in SLS performed in the excimer laser laboratory of TRINITI research institute, Russia, where different types of excimer lasers have been developed and manufactured. The research used a new simple SLS approach based on single-axis (i.e., cylinder) projection optics. The method employs a long single melting line extended many centimeters in length. The line is formed by projection through a single slit in a bulk metal mask. Some aspects of the efficiency, potential, and technical challenge of the method are discussed. This method is particularly useful with low pulse energy and high frequency excimer lasers, and one of the most efficient ways of providing directionally crystallized Si films over a large area. Several types of excimer lasers were tested for the SLS technique. It was found that among various parameters, pulse duration is a more important one, e.g., an increase in pulse duration from 25 to 150 ns results in enlargement of lateral growth distance by about three times.

Dichotomy of the Hydrogen Atom in Superintense, High-Frequency Laser Fields

1988 ◽  
Vol 61 (8) ◽  
pp. 939-942 ◽  
Author(s):  
M. Pont ◽  
N. R. Walet ◽  
M. Gavrila ◽  
C. W. McCurdy
Keyword(s):  
Hydrogen Atom ◽  
High Frequency ◽  
Laser Fields ◽  
Frequency Laser
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