FREQUENCY EFFECTS AND CLASSICAL PATHS IN STRONG-FIELD IONIZATION

1995 ◽  
Vol 04 (03) ◽  
pp. 687-700
Author(s):  
H. R. REISS
Keyword(s):  
High Frequency ◽  
Field Experiments ◽  
Strong Field ◽  
Polarized Light ◽  
High Energy ◽  
Frequency Theory ◽  
Photoelectron Spectra ◽  
Energy Conditions ◽  
Circularly Polarized Light ◽  
Wide Range

The ability of the SFA (strong-field approximation) to predict the ionization of atoms at all frequencies is explored at low frequency by comparison with experiment. Excellent agreement is found over a very wide range of high intensities. At high frequency, where no precision strong-field experiments are available, a comparison is made between predictions of the SFA and a high-frequency theory due to Gavrila. Agreement in transition rates is very good. The disagreement in the assignment of energy conditions at high frequencies is explained as a difference in interpretation brought about by the gauge transformation employed by Gavrila. An examination of semiclassical path behavior of a photoelectron after ionization gives insight on the lower limits of intensity for which the SFA is applicable, and makes transparent the meaning of a recently applied Coulomb correction to the SFA for circularly polarized light. A related examination for linearly polarized light gives an effective high energy limit for intense-field photoelectron spectra.

scholarly journals Strong field double ionization of Helium with ultra short circularly polarized light pulses

2012 ◽  
Vol 388 (3) ◽  
pp. 032071
Author(s):  
M S Schöffler ◽  
X Xie ◽  
S Roither ◽  
D Kartashov ◽  
A Baltuska ◽  
...  
Keyword(s):  
Strong Field ◽  
Polarized Light ◽  
Double Ionization ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Light Pulses

scholarly journals Circularly Polarized Light Detection by Chiral Photonic Cellulose Nanocrystal with ZnO Photoconductive Layer in Ultraviolet Region

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3098
Author(s):  
Boyu Zhang ◽  
Sixiang Zhao ◽  
Yingying Yu ◽  
Ming Li ◽  
Liancheng Zhao ◽  
...  
Keyword(s):  
Self Assembly ◽  
Polarization State ◽  
Polarized Light ◽  
Cellulose Nanocrystal ◽  
Ultraviolet Region ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left Handed ◽  
Chiral Nematic ◽  
Wide Range

Circularly polarized light (CPL) detection and polarization state recognition are required for a wide range of applications. Conventional polarization detection with optical components causes difficulties for miniaturization and integration. An effective design strategy is proposed for direct CPL detection with chiral material. Here, we realized direct CPL detection based on the combination of chiral photonic cellulose nanocrystal (CNC) and ultraviolet-sensitive ZnO photoconductive material. The CNC layer deposited by evaporation-induced self-assembly established the left-handed chiral nematic structure with a photonic bandgap (PBG) to recognize left-handed CPL (LCPL) and right-handed CPL (RCPL) at specific wavelengths. The PBG of CNC layer has been modulated by the adjustment of chiral nematic pitch to match the semiconductor bandgap of ZnO film in ultraviolet region. The photocurrents under RCPL and LCPL are 2.23 × 10−6 A and 1.77 × 10−6 A respectively and the anisotropy factor Δgpc of 0.23 is acquired for the CPL detection based on the chiral photonic CNC. This design provides a new approach to the detection of CPL polarization state with competitive performance.

scholarly journals Wave and Tidal Controls on Embayment Circulation and Headland Bypassing for an Exposed, Macrotidal Site

2018 ◽  
Vol 6 (3) ◽  
pp. 94 ◽  
Author(s):  
R. McCarroll ◽  
Gerd Masselink ◽  
Nieves Valiente ◽  
Tim Scott ◽  
Erin King ◽  
...  
Keyword(s):  
Extreme Events ◽  
High Energy ◽  
Water Levels ◽  
Energy Conditions ◽  
Coastal Change ◽  
Extreme Waves ◽  
Starting Point ◽  
Wide Range ◽  
Order Of Magnitude ◽  
A Site

Headland bypassing is the transport of sediment around rocky headlands by wave and tidal action, associated with high-energy conditions and embayment circulation (e.g., mega-rips). Bypassing may be a key component in the sediment budget of many coastal cells, the quantification of which is required to predict the coastal response to extreme events and future coastal change. Waves, currents, and water levels were measured off the headland of a sandy, exposed, and macrotidal beach in 18-m and 26-m depths for 2 months. The observations were used to validate a Delft3D morphodynamic model, which was subsequently run for a wide range of scenarios. Three modes of bypassing were determined: (i) tidally-dominated control during low–moderate wave conditions [flux O (0–102 m3 day−1)]; (ii) combined tidal- and embayment circulation controls during moderate–high waves [O (103 m3 day−1)]; and (iii) multi-embayment circulation control during extreme waves [O (104 m3 day−1)]. A site-specific bypass parameter is introduced, which accurately (R2 = 0.95) matches the modelled bypass rates. A 5-year hindcast predicts bypassing is an order of magnitude less than observed cross-shore fluxes during extreme events, suggesting that bypassing at this site is insignificant at annual timescales. This work serves a starting point to generalise the prediction of headland bypassing.

scholarly journals Pair production by Schwinger and Breit–Wheeler processes in bi-frequent fields

2016 ◽  
Vol 82 (3) ◽  
Author(s):  
A. Otto ◽  
T. Nousch ◽  
D. Seipt ◽  
B. Kämpfer ◽  
D. Blaschke ◽  
...  
Keyword(s):  
Pair Production ◽  
High Frequency ◽  
Polarized Light ◽  
High Energy ◽  
Intense Laser ◽  
Laser Beams ◽  
High Intensity Laser ◽  
Linearly Polarized ◽  
Intensity Laser ◽  
Probe Photon

Counter-propagating and suitably polarized light (laser) beams can provide conditions for pair production. Here, we consider in more detail the following two situations: (i) in the homogeneity regions of anti-nodes of linearly polarized ultra-high intensity laser beams, the Schwinger process is dynamically assisted by a second high-frequency field, e.g. by an XFEL beam; and (ii) a high-energy probe photon beam colliding with a superposition of co-propagating intense laser and XFEL beams gives rise to the laser-assisted Breit–Wheeler process. The prospects of such bi-frequent field constellations with respect to the feasibility of conversion of light into matter are discussed.

scholarly journals The Influence of Milling Conditions on the Ni3Fe Alloyed Powder

2015 ◽  
Vol 13 ◽  
pp. 75-82
Author(s):  
Călin Virgiliu Prică ◽  
Cristina Daniela Stanciu ◽  
Florin Popa ◽  
Ionel Chicinaş
Keyword(s):  
High Frequency ◽  
Rotation Speed ◽  
High Energy ◽  
Milling Process ◽  
Planetary Mill ◽  
Energy Conditions ◽  
Particle Sizes ◽  
Grain Sizes ◽  
Disk Rotation ◽  
The Impact

The mechanosynthesis of Ni3Fe intermetallic compound was carried out in a planetary mill. The effects of milling parameters such as balls diameters and ball milling speed defined by the vials rotation speed (ω) and the disk rotation speed (Ω), on morphology, microstructure and particle sizes of Ni3Fe powder were studied. It was found that the impact frequency represented by the number of balls from vials is an important parameter a milling process. The smaller grain sizes and particle was obtained when milling process was performed in high frequency rate of impacts together with high balls velocity, meaning high energy conditions.

Effects of Deposition Angle on the Optical Properties of Helically Structured Films

2004 ◽  
Vol 846 ◽  
Author(s):  
Jason B. Sorge ◽  
Andy C. van Popta ◽  
Jeremy C. Sit ◽  
Michael J. Brett
Keyword(s):  
Thin Films ◽  
Tilt Angle ◽  
Polarized Light ◽  
Anisotropic Scattering ◽  
Helical Structures ◽  
Circularly Polarized Light ◽  
Variable Porosity ◽  
Wide Range ◽  
Porous Thin Film ◽  
Deposition Angle

ABSTRACTGlancing-angle deposition (GLAD) is a fabrication method capable of producing thin films with variable porosity. The GLAD process exploits substrate shadowing and limited adatom diffusion to create isolated columns of material that collectively comprise a highly porous thin film. GLAD can be used to create chiral or helical structures with a wide range of porosity through variation of the substrate tilt angle and controlled substrate rotation. We present the effect of the deposition angle on the selective transmittance of circularly polarized light in helical thin films fabricated with the GLAD process. Transmission measurements of titanium dioxide helical films reveal two regimes of enhanced selective transmittance: one corresponding to a substrate tilt angle that produces a maximum circular birefringence and another corresponding to strong anisotropic scattering.

scholarly journals Tomographic reconstruction of circularly polarized high-harmonic fields: 3D attosecond metrology

2016 ◽  
Vol 2 (2) ◽  
pp. e1501333 ◽  
Author(s):  
Cong Chen ◽  
Zhensheng Tao ◽  
Carlos Hernández-García ◽  
Piotr Matyba ◽  
Adra Carr ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Tomographic Reconstruction ◽  
High Harmonic ◽  
Polarized Light ◽  
Copper Surface ◽  
Photoelectron Spectra ◽  
Laser Fields ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Linearly Polarized

Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

scholarly journals The GALAXIES inelastic hard X-ray scattering end-station at Synchrotron SOLEIL

2019 ◽  
Vol 26 (1) ◽  
pp. 263-271 ◽  
Author(s):  
J. M. Ablett ◽  
D. Prieur ◽  
D. Céolin ◽  
B. Lassalle-Kaiser ◽  
B. Lebert ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Polarized Light ◽  
Research Direction ◽  
High Energy ◽  
High Energy Resolution ◽  
X Rays ◽  
Circularly Polarized Light ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

GALAXIES is an in-vacuum undulator hard X-ray micro-focused beamline dedicated to the study of the electronic structure of materials with high energy resolution using both photoelectron spectroscopy and inelastic X-ray scattering and under both non-resonant (NR-IXS) and resonant (RIXS) conditions. Due to the penetrating power of hard X-rays and the `photon-in/photon-out' technique, the sample environment is not a limitation. Materials under extreme conditions, for example in diamond anvil cells or catalysis chambers, thus constitute a major research direction. Here, the design and performance of the inelastic X-ray scattering end-station that operates in the energy range from ∼4 keV up to 12 keV is reported, and its capabilities are highlighted using a selection of data taken from recently performed experiments. The ability to scan `on the fly' the incident and scattered/emitted X-ray energies, and the sample position enables fast data collection and high experimental throughput. A diamond X-ray transmission phase retarder, which can be used to generate circularly polarized light, will also be discussed in the light of the recent RIXS–MCD approach.

scholarly journals An Novel Atomic Scalar Magnetometer Using Laser

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Relaxation Rate ◽  
High Frequency ◽  
Polarized Light ◽  
Optical Path ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Scalar Magnetometer ◽  
Static Sensitivity ◽  
Discharge Excitation ◽  
Excitation Circuit

The measurement precision of commercial atom scalar magnetometer is relatively backward compared with that of quantum magnetometer. However, the application of quantum magnetometers such as SERF requires more stringent environmental background requirements, which is not suitable for magnetic field measurement in the geomagnetic environment. The purpose of this paper is to design a 4He atom scalar magnetometer using ECDL laser. Compared with the conventional atomic scalar magnetometer, this magnetometer has higher measuring precision and can work normally in the geomagnetic environment. In order to achieve the above goals, the sensitivity formula of the atomic scalar magnetometer is first deduced and calculated, and the key physical factors that directly affect the sensitivity are the optical pumping rate, transverse relaxation rate, and longitudinal relaxation rate. Then, the light source and 4He cell are determined as key components which affect sensitivity. On this basis, the optical path of the 4He atomic scalar magnetometer using laser is designed in this paper. The light path ensures the stability of the laser wavelength of 1083.207nm by the saturation absorption spectrum method, and it ensures the circularly polarized light enters the 4He cell through the combination of various optical components. This paper also studies the electric excitation technology of the 4He cell. And, combined with simulation experiments, the High-Frequency discharge excitation circuit with high energy transfer efficiency and corresponding matching network are determined. Through the optical wavelength meter, it can be determined that the optical path designed in this paper can guarantee the wavelength stability of 1083.207nm for a long time. By analyzing the detection signals of PD, the circularly polarized light enters the 4He cell in the light circuit designed in this paper has a higher degree of polarization. The High-Frequency discharge excitation circuit designed in this paper can light up the cell smoothly, and the input power when the circuit works stably is about 6W. Finally, the static sensitivity of the magnetometer is 5pT/Hz1/2. The 4He atom scalar magnetometer using ECDL laser designed in this paper has high static sensitivity, which basically meets the design requirements, and the instrument can be used normally in the geomagnetic environment. However, the instrument still has a lot of room for improvement, including optical path and cell performance optimization, and we will continue to study in this direction.

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