scholarly journals Direct Classic Route of Generating Mono-Color EM-Pulse with Attosecond-Level Duration

2019 ◽  
Vol 9 (3) ◽  
pp. 362 ◽  
Author(s):  
Hai Lin ◽  
Chengpu Liu
Keyword(s):  
Fourier Spectrum ◽  
Geometric Dimension ◽  
Single Pulse ◽  
Field Configuration ◽  
High Order ◽  
Equal Weight ◽  
Time Duration ◽  
Driving Field ◽  
Homogeneous Weight ◽  
Indirect Route

Current conception of attosecond pulse is based on Fourier optics and refers to an electromagnetic pulse with a broad, homogeneous weight Fourier spectrum. Its preparation/generation is along an indirect route in which the output of commercial available μ m-level wavelength laser is “processed” by elaborately designed optics medium allowing high-order harmonics effect to change its Fourier spectrum to be of a flat high-frequency tail. Such an indirect, quantum scheme is limited by its efficiency in high-order harmonics generation. For higher efficiency, other routes for the same goal, i.e., light pulse with an attosecond-level duration, deserve to be tried. The method proposed is a direct, classic scheme. It is to directly control the time duration of classic electrons doing acceleration/deceleration in a feasible, elaborately-designed driving DC fields configuration. The duration can be adjusted by initial electrons velocity, geometric dimension of driving field configuration. The maximum strength of a generated pulse is controlled by the number of electrons. The frequency of a generated pulse is controlled by initial electrons position in the configuration. The shortest duration of single pulse can be down to sub-attosecond-level according to currently available minimum geometric dimension of driving field and suitable gesture of electrons entering into the driving field configuration. This work displays a feasible, direct, classic route of achieving EM pulse with an attosecond-level duration. In particular, the pulse is mono-color, rather than a superposition of Fourier components with nearly-equal weight.

scholarly journals High-order harmonics measured by the photon statistics of the infrared driving-field exiting the atomic medium

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
N. Tsatrafyllis ◽  
I. K. Kominis ◽  
I. A. Gonoskov ◽  
P. Tzallas
Keyword(s):  
High Order ◽  
Photon Statistics ◽  
Driving Field ◽  
Atomic Medium

scholarly journals Symmetries and Selection Rules of the Spectra of Photoelectrons and High-Order Harmonics Generated by Field-Driven Atoms and Molecules

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1566
Author(s):  
Dino Habibović ◽  
Wilhelm Becker ◽  
Dejan B. Milošević
Keyword(s):  
Molecular Targets ◽  
Dynamical Symmetry ◽  
High Order ◽  
Photoelectron Spectra ◽  
Selection Rules ◽  
Driving Field ◽  
Dynamical Symmetries ◽  
High Order Harmonic ◽  
Born Series ◽  
Symmetry Properties

Using the strong-field approximation we systematically investigate the selection rules for high-order harmonic generation and the symmetry properties of the angle-resolved photoelectron spectra for various atomic and molecular targets exposed to one-component and two-component laser fields. These include bicircular fields and orthogonally polarized two-color fields. The selection rules are derived directly from the dynamical symmetries of the driving field. Alternatively, we demonstrate that they can be obtained using the conservation of the projection of the total angular momentum on the quantization axis. We discuss how the harmonic spectra of atomic targets depend on the type of the ground state or, for molecular targets, on the pertinent molecular orbital. In addition, we briefly discuss some properties of the high-order harmonic spectra generated by a few-cycle laser field. The symmetry properties of the angle-resolved photoelectron momentum distribution are also determined by the dynamical symmetry of the driving field. We consider the first two terms in a Born series expansion of the T matrix, which describe the direct and the rescattered electrons. Dynamical symmetries involving time translation generate rotational symmetries obeyed by both terms. However, those that involve time reversal generate reflection symmetries that are only observed by the direct electrons. Finally, we explain how the symmetry properties, imposed by the dynamical symmetry of the driving field, are altered for molecular targets.

Effect of elliptical polarization of driving field on high-order-harmonic generation in semiconductor ZnO

2016 ◽  
Vol 93 (4) ◽  
Author(s):  
Candong Liu ◽  
Yinghui Zheng ◽  
Zhinan Zeng ◽  
Ruxin Li
Keyword(s):  
Harmonic Generation ◽  
High Order ◽  
Elliptical Polarization ◽  
High Order Harmonic Generation ◽  
Driving Field ◽  
High Order Harmonic

Dramatic extension of the high-order harmonic cutoff by using a long-wavelength driving field

2001 ◽  
Vol 65 (1) ◽  
Author(s):  
Bing Shan ◽  
Zenghu Chang
Keyword(s):  
High Order ◽  
Driving Field ◽  
Long Wavelength ◽  
High Order Harmonic

scholarly journals Design of a time-compensated EUV and soft X-ray monochromator with multilayer mirrors for high-order harmonics

2001 ◽  
Vol 19 (1) ◽  
pp. 141-145
Author(s):  
LUCA POLETTO ◽  
GIUSEPPE TONDELLO
Keyword(s):  
Normal Incidence ◽  
Vertical Axis ◽  
Grazing Incidence ◽  
High Order ◽  
Time Duration ◽  
X Ray ◽  
Incidence Plane ◽  
Constant Direction ◽  
Axis Parallel ◽  
Exit Beam

A time-compensated monochromator for ultrashort high-order harmonics in the EUV and soft X-ray regions is presented. The system consists of two grazing-incidence toroidal mirrors used, respectively, as collimating and refocusing elements and of two multilayer normal-incidence plane mirrors illuminated in parallel light that rotate along a vertical axis to select the operative wavelength, but remain parallel to guarantee the constant direction of the exit beam. This is performed by simultaneously rotating and translating one of the two mirrors along an axis parallel to the exit direction. The pulse time duration is not altered up to few femtoseconds.

Electron holography in materials science

1991 ◽  
Vol 49 ◽  
pp. 670-671
Author(s):  
Hannes Lichte ◽  
Edgar Voelkl
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Materials Science ◽  
Fourier Spectrum ◽  
Object Wave ◽  
Electron Holography ◽  
Reconstruction Procedure ◽  
Numerical Reconstruction ◽  
Transmission Electron ◽  
Unique Interpretation

The object wave o(x,y) = a(x,y)exp(iφ(x,y)) at the exit face of the specimen is described by two real functions, i.e. amplitude a(x,y) and phase φ(x,y). In stead of o(x,y), however, in conventional transmission electron microscopy one records only the real intensity I(x,y) of the image wave b(x,y) loosing the image phase. In addition, referred to the object wave, b(x,y) is heavily distorted by the aberrations of the microscope giving rise to loss of resolution. Dealing with strong objects, a unique interpretation of the micrograph in terms of amplitude and phase of the object is not possible. According to Gabor, holography helps in that it records the image wave completely by both amplitude and phase. Subsequently, by means of a numerical reconstruction procedure, b(x,y) is deconvoluted from aberrations to retrieve o(x,y). Likewise, the Fourier spectrum of the object wave is at hand. Without the restrictions sketched above, the investigation of the object can be performed by different reconstruction procedures on one hologram. The holograms were taken by means of a Philips EM420-FEG with an electron biprism at 100 kV.

Effects of compression during formation on the microstructure of composite hydroxylapatite/plaster implants for bone reconstruction

1988 ◽  
Vol 46 ◽  
pp. 750-751
Author(s):  
J. Hanker ◽  
K. Cowden ◽  
R. Noecker ◽  
P. Yates ◽  
N. Georgiade ◽  
...  
Keyword(s):  
Cosmetic Surgery ◽  
Glass Plate ◽  
Surgical Reconstruction ◽  
Equal Weight ◽  
Sintered Ceramic ◽  
Setting Times ◽  
Excess Water ◽  
Mixture Prior ◽  
Mechanical Strengths ◽  
Calcium Sulfate Hemihydrate

Composites of plaster of Paris (PP) and hydroxylapatite (HA) particles are being applied for the surgical reconstruction of craniofacial bone defects and for cosmetic surgery. Two types of HA particles are being employed, the dense sintered ceramic (DHA) and the porous, coralline hydroxylapatite (PHA) particles. Excess water is expressed out of the moistened HA/PP mixture prior to implantation and setting by pressing it in a non-tapered syringe against a glass plate. This results in implants with faster setting times and greater mechanical strengths. It was therefore of interest to compare samples of the compressed versus noncompressed mixtures to see whether or not any changes in their microstructure after setting could be related to these different properties.USG Medical Grade Calcium Sulfate Hemihydrate (which has the lowest mortar consistency of any known plaster) was mixed with an equal weight of Interpore 200 particles (a commercial form of PHA). After moistening with a minimum amount of water, disc-shaped noncompressed samples were made by filling small holes (0.339 in. diameter x 0.053 in. deep) in polypropylene molds with a microspatula.

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