scholarly journals Tungsten Thermionic Emission as a Gauge for Low Pressures of Cesium Vapor

Instruments ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 34
Author(s):  
João Shida ◽  
Fangjian Wu ◽  
Eric Spieglan ◽  
Mesut Çalışkan
Keyword(s):  
Alkali Metal ◽  
Electric Fields ◽  
Second Generation ◽  
Thermionic Emission ◽  
Cesium Vapor ◽  
Tungsten Filament ◽  
Large Area ◽  
Low Pressures ◽  
Heated Metal ◽  
Proof Of Principle

Heated metal filaments under electric fields and low pressures of alkali metal gas eject electrons by thermionic emission as a function of the pressure of the gas and the temperature of the filament. To explore this process in a program to develop large-area alkali metal photocathodes, we have designed and built a gauge following the studies of Taylor and Langmuir. We present proof-of-principle measurements of the thermionic emission of a tungsten filament in cesium vapor. We describe a second-generation design that corrects flaws in the first gauge.

scholarly journals Large-area printing of ferroelectric surface and super-domains for efficient solar water splitting

2020 ◽  
Author(s):  
Yu Tian ◽  
Yaqing Wei ◽  
Minghui Pei ◽  
Rongrong Cao ◽  
Zhenao Gu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Electric Fields ◽  
Electronic Structures ◽  
Active Sites ◽  
Large Area ◽  
Solar Water Splitting ◽  
High Efficient ◽  
Catalytic Sites ◽  
Order Of Magnitude ◽  
Magnitude Increase

Abstract Surface electronic structures of the photoelectrodes determine the activity and efficiency of the photoelectrochemical water splitting, but the controls of their surface structures and interfacial chemical reactions remain challenging. Here, we use ferroelectric BiFeO3 as a model system to demonstrate an efficient and controllable water splitting reaction by large-area constructing the hydroxyls-bonded surface. The up-shift of band edge positions at this surface enables and enhances the interfacial holes and electrons transfer through the hydroxyl-active-sites, leading to simultaneously enhanced oxygen and hydrogen evolutions. Furthermore, printing of ferroelectric super-domains with microscale checkboard up/down electric fields separates the distribution of reduction/oxidation catalytic sites, enhancing the charge separation and giving rise to an order of magnitude increase of the photocurrent. This large-area printable ferroelectric surface and super-domains offer an alternative platform for controllable and high-efficient photocatalysis.

Layers of Caesium, and Nitrogen on Tungsten

1929 ◽  
Vol 25 (3) ◽  
pp. 347-354
Author(s):  
N. A. de Bruyne
Keyword(s):  
Low Temperatures ◽  
Thermionic Emission ◽  
Tungsten Filament ◽  
Initial Rise ◽  
Tungsten Surface

While investigating the effect of a caesium film on the auto-electronic emission from a tungsten surface I noticed certain phenomena which seemed worth further investigation. Langmuir and Kingdon have shown that the emission from a tungsten filament in caesium vapour varies with the temperature of the filament in the manner shown in Fig. 1. The initial rise in the emission at low temperatures is due to the existence of a caesium layer on the filament. At higher temperatures the caesium evaporates and the emission drops until eventually the temperature becomes high enough to produce a thermionic emission from the clean tungsten surface.

Second generation large area microchannel plate flat panel phototubes

2016 ◽  
Author(s):  
C. D. Ertley ◽  
O. H. W. Siegmund ◽  
S. R. Jelinsky ◽  
J. Tedesco ◽  
M. J. Minot ◽  
...  
Keyword(s):  
Second Generation ◽  
Microchannel Plate ◽  
Large Area ◽  
Flat Panel

scholarly journals Long-range interactions between polar alkali-metal diatoms in external electric fields

2013 ◽  
Vol 88 (3) ◽  
Author(s):  
M. Lepers ◽  
R. Vexiau ◽  
M. Aymar ◽  
N. Bouloufa-Maafa ◽  
O. Dulieu
Keyword(s):  
Alkali Metal ◽  
Long Range ◽  
Electric Fields ◽  
External Electric Fields ◽  
Long Range Interactions

Implications for Ultrafast Reflection Electron Diffraction from Temporal and Spatial Evolution of Transient Electric Fields

2009 ◽  
Vol 1230 ◽  
Author(s):  
Hyuk Park ◽  
J.M. Zuo
Keyword(s):  
Electron Diffraction ◽  
Electric Fields ◽  
Materials Science ◽  
Thermionic Emission ◽  
Sample Surface ◽  
High Energy ◽  
Intense Laser ◽  
Hot Electron ◽  
Time Resolved ◽  
Reflection Electron Diffraction

AbstractUnderstanding interaction of ultrafast pulsed laser with matter is critical for probing ultrafast processes in materials science, understanding the physics of laser ablation and the laser induced non-equilibrium carrier dynamics in metals and semiconductors, including plasmonics. When an intense laser pulse of femtoseconds (fs) in duration hits the surface of a targeted matter, it excites a hot electron gas. Part of the hot electrons is emitted from the surface in a way similar to thermionic emission. Electrons can also be emitted through multiphoton photoemission (MPPE) or thermally assisted MPPE. The emitted electrons travel at speeds that create transient electric fields (TEFs). To detect TEFs and study the dynamics of emitted electrons, we have developed a time resolved electron beam imaging technique that allows us to measure TEFs above a sample surface at picoseconds time resolution. We have also developed a model of the TEFs based on the propagation of emitted electrons and the percentage of electrons escaping from the surface. We examine the significance of TEFs for ultrafast reflection electron diffraction by examining anomalous effects in ultrafast reflection high energy electron diffraction (RHEED) of silicon surfaces.

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