scholarly journals Terahertz Photoconductivity Spectra of Electrodeposited Thin Bi Films

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3150
Author(s):  
Ignas Nevinskas ◽  
Zenius Mockus ◽  
Remigijus Juškėnas ◽  
Ričardas Norkus ◽  
Algirdas Selskis ◽  
...  
Keyword(s):  
Spatial Separation ◽  
Thz Radiation ◽  
Electron Dynamics ◽  
Optical Pulses ◽  
Electrolyte Additive ◽  
Spectra Analysis ◽  
Grain Sizes ◽  
Carrier Scattering ◽  
Bismuth Films ◽  
Triton X

Electron dynamics in the polycrystalline bismuth films were investigated by measuring emitted terahertz (THz) radiation pulses after their photoexcitation by tunable wavelength femtosecond duration optical pulses. Bi films were grown on metallic Au, Pt, and Ag substrates by the electrodeposition method with the Triton X-100 electrolyte additive, which allowed us to obtain more uniform films with consistent grain sizes on any substrate. It was shown that THz pulses are generated due to the spatial separation of photoexcited electrons and holes diffusing from the illuminated surface at different rates. The THz photoconductivity spectra analysis has led to a conclusion that the thermalization of more mobile carriers (electrons) is dominated by the carrier–carrier scattering rather than by their interaction with the lattice.

scholarly journals Analytical Theory of Attosecond Transient Absorption Spectroscopy of Perturbatively Dressed Systems

2019 ◽  
Vol 9 (7) ◽  
pp. 1350
Author(s):  
Daria Kolbasova ◽  
Robin Santra
Keyword(s):  
Perturbation Theory ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Electronic States ◽  
Theoretical Description ◽  
Transient Absorption Spectroscopy ◽  
Electron Dynamics ◽  
Optical Pulses ◽  
Absorption Signal ◽  
Level Model

A theoretical description of attosecond transient absorption spectroscopy for temporally and spatially overlapping XUV and optical pulses is developed, explaining the signals one can obtain in such an experiment. To this end, we employ a two-stage approach based on perturbation theory, which allows us to give an analytical expression for the transient absorption signal. We focus on the situation in which the attosecond XUV pulse is used to create a coherent superposition of electronic states. As we explain, the resulting dynamics can be detected in the spectrum of the transmitted XUV pulse by manipulating the electronic wave packet using a carrier-envelope-phase-stabilized optical dressing pulse. In addition to coherent electron dynamics triggered by the attosecond pulse, the transmitted XUV spectrum encodes information on electronic states made accessible by the optical dressing pulse. We illustrate these concepts through calculations performed for a few-level model.

Temperature Dependence of THz Radiation from Flux-Trapped YBa2Cu3O7-δ Thin Films Excited by Ultrashort Optical Pulses

1998 ◽  
pp. 1231-1234 ◽  
Author(s):  
Shin-ichi Shikii ◽  
Noboru Wada ◽  
Masayoshi Tonouchi ◽  
Masanori Hangyo ◽  
Masahiko Tani ◽  
...  
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Thz Radiation ◽  
Optical Pulses ◽  
Ultrashort Optical Pulses

scholarly journals Design of a Pre-Bunched THz Free Electron Laser

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 267-278 ◽  
Author(s):  
Ruixuan Huang ◽  
Weiwei Li ◽  
Zhouyu Zhao ◽  
Heting Li ◽  
Jigang Wang ◽  
...  
Keyword(s):  
Free Electron ◽  
Free Electron Laser ◽  
Peak Power ◽  
Tuning Range ◽  
Second Harmonic ◽  
Industrial Applications ◽  
Thz Radiation ◽  
Fundamental Wave ◽  
Electron Dynamics ◽  
Main Components

Terahertz (THz) radiation has attracted much attention in new scientific and industrial applications. There has been significant recent progress in generating THz with accelerators. To investigate the collective behavior of electron dynamics, we have proposed a new high throughput material characterization system, which supplies a multiple light source. The system includes a pre-bunched THz free electron laser (FEL), which is a high-power narrow-band THz source with a wide tuning range of frequency. The physical design with the main components of the facility is introduced, and the simulation results are illustrated. Radiation of 0.5–3.0 THz is obtained by the fundamental wave of the pre-bunched beam, and radiation covering 3.0–5.0 THz is realized by second harmonic generation. As the simulation shows, intense THz radiation could be achieved in a frequency from 0.5–5.0 THz, with a peak power of several megawatts (MWs) and a bandwidth of a few percent.

Generation of Strong Short Terahertz Pulses via Stimulated Raman Adiabatic Passage-assisted Coherent Scattering

2006 ◽  
Vol 935 ◽  
Author(s):  
Nikolai Kalugin ◽  
Yuri Rostovtsev ◽  
Marlan O. Scully
Keyword(s):  
Room Temperature ◽  
Coherent Scattering ◽  
Thz Radiation ◽  
Adiabatic Passage ◽  
Optical Pulses ◽  
Molecular Gases ◽  
Terahertz Pulses ◽  
Correct Sequence ◽  
Pulse Energies ◽  
Red Radiation

ABSTRACTWe analyzed the efficiency of coherent scattering of infrared radiation in atomic and molecular gases for production of intense short THz pulses, using simulated Raman adiabatic passage (STIRAP). The method is based on excitation of maximal coherence when the system is undergoing through STIRAP in IR-irradiated atomic or molecular gases (for example Rb, methanol, and others) at room temperature. By applying optical pulses in correct sequence one can generate coherence in a system during STIRAP which triggers following coherent scattering of infra-red radiation, and can produce pulses of THz radiation with pulse energies ranging from several nJ to µ-J and pulse durations from several fs to ns.

scholarly journals Electron dynamics in chromium probed with 20-fs optical pulses

2003 ◽  
Vol 68 (11) ◽  
Author(s):  
H. Hirori ◽  
T. Tachizaki ◽  
O. Matsuda ◽  
O. B. Wright
Keyword(s):  
Electron Dynamics ◽  
Optical Pulses

scholarly journals The Integrin α6β4 Functions in Carcinoma Cell Migration on Laminin-1 by Mediating the Formation and Stabilization of Actin-containing Motility Structures

1997 ◽  
Vol 139 (7) ◽  
pp. 1873-1884 ◽  
Author(s):  
Isaac Rabinovitz ◽  
Arthur M. Mercurio
Keyword(s):  
Carcinoma Cell ◽  
Spatial Separation ◽  
Time Lapse ◽  
Functional Studies ◽  
A Cells ◽  
Integrin Α6β4 ◽  
Α6β4 Integrin ◽  
Tween 40 ◽  
Triton X ◽  
Laminin 1

Functional studies on the α6β4 integrin have focused primarily on its role in the organization of hemidesmosomes, stable adhesive structures that associate with the intermediate filament cytoskeleton. In this study, we examined the function of the α6β4 integrin in clone A cells, a colon carcinoma cell line that expresses α6β4 but no α6β1 integrin and exhibits dynamic adhesion and motility on laminin-1. Time-lapse videomicroscopy of clone A cells on laminin-1 revealed that their migration is characterized by filopodial extension and stabilization followed by lamellae that extend in the direction of stabilized filopodia. A function-blocking mAb specific for the α6β4 integrin inhibited clone A migration on laminin-1. This mAb also inhibited filopodial formation and stabilization and lamella formation. Indirect immunofluorescence microscopy revealed that the α6β4 integrin is localized as discrete clusters in filopodia, lamellae, and retraction fibers. Although β1 integrins were also localized in the same structures, a spatial separation of these two integrin populations was evident. In filopodia and lamellae, a striking colocalization of the α6β4 integrin and F-actin was seen. An association between α6β4 and F-actin is supported by the fact that α6β4 integrin and actin were released from clone A cells by treatment with the F-actin– severing protein gelsolin and that α6β4 immunostaining at the marginal edges of clone A cells on laminin-1 was resistant to solubilization with Triton X-100. Cytokeratins were not observed in filopodia and lamellipodia. Moreover, α6β4 was extracted from these marginal edges with a Tween-40/deoxycholate buffer that solubilizes the actin cytoskeleton but not cytokeratins. Three other carcinoma cell lines (MIP-101, CCL-228, and MDA-MB-231) exhibited α6β4 colocalized with actin in filopodia and lamellae. Formation of lamellae in these cells was inhibited with an α6-specific antibody. Together, these results indicate that the α6β4 integrin functions in carcinoma migration on laminin-1 through its ability to promote the formation and stabilization of actin-containing motility structures.

Electron Dynamics in Copper Metallic Nanoparticles Probed with Femtosecond Optical Pulses

1995 ◽  
Vol 75 (25) ◽  
pp. 4702-4705 ◽  
Author(s):  
J. -Y. Bigot ◽  
J. -Y. Merle ◽  
O. Cregut ◽  
A. Daunois
Keyword(s):  
Metallic Nanoparticles ◽  
Electron Dynamics ◽  
Optical Pulses

scholarly journals Terahertz Emission and Ultrafast Carrier Dynamics of Ar-Ion Implanted Cu(In,Ga)Se2 Thin Films

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 411
Author(s):  
Chul Kang ◽  
Gyuseok Lee ◽  
Woo-Jung Lee ◽  
Dae-Hyung Cho ◽  
Inhee Maeng ◽  
...  
Keyword(s):  
Thin Films ◽  
Carrier Dynamics ◽  
Thz Radiation ◽  
Terahertz Emission ◽  
Optical Pump ◽  
Carrier Scattering ◽  
Ultrafast Carrier ◽  
Probe Spectroscopy ◽  
Surge Current ◽  
Ion Implanted

We investigated THz emission from Ar-ion-implanted Cu(In,Ga)Se2 (CIGS) films. THz radiation from the CIGS films increases as the density of implanted Ar ions increases. This is because Ar ions contribute to an increase in the surface surge current density. The effect of Ar-ion implantation on the carrier dynamics of CIGS films was also investigated using optical pump THz probe spectroscopy. The fitted results imply that implanted Ar ions increase the charge transition of intra-and carrier–carrier scattering lifetimes and decrease the bandgap transition lifetime.

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