scholarly journals Electroionization study of ethane: structures in the ionization and appearance curves

1987 ◽  
Vol 65 (9) ◽  
pp. 2004-2008 ◽  
Author(s):  
Pierre Plessis ◽  
Paul Marmet
Keyword(s):  
Carbon Atom ◽  
Signal To Noise Ratio ◽  
Negative Ion ◽  
High Signal ◽  
Feshbach Resonances ◽  
Signal To Noise ◽  
Monoenergetic Electron ◽  
Fragment Ions ◽  
Novel Structures ◽  
Very High

Ionization efficiency curves of very high signal-to-noise ratio are presented for ethane and most fragment ions containing at least one carbon atom. These curves, which are produced by monoenergetic electron impact, extend up to 10 eV above the initial onsets. Novel structures are observed in most curves. Certain features appear at the same energy in several of the curves indicating that they belong to a common progenitor, either [Formula: see text] or [Formula: see text], and not directly to the detected ions. These sets of structure are attributed to negative ion states (Feshbach resonances) and/or to Rydberg autoionizing states.

Electroionization study of ethylene: structures in the ionization and appearance curves

1987 ◽  
Vol 65 (7) ◽  
pp. 803-807 ◽  
Author(s):  
Pierre Plessis ◽  
Paul Marmet
Keyword(s):  
Carbon Atom ◽  
High Signal ◽  
Signal To Noise ◽  
Monoenergetic Electron ◽  
Text Production ◽  
Text Fragment ◽  
First Time ◽  
Fragmentation Processes ◽  
Fragment Production ◽  
Very High

Ionization-efficiency curves with very high signal-to-noise ratios for ethylene and all fragments consisting of at least one carbon atom are presented and analyzed. The curves are produced by monoenergetic electron impact and extend up to 10 eV above threshold. Most of the structures observed thus far by this method for these regions are reported here for the first time. Competition between [Formula: see text] production and [Formula: see text] and [Formula: see text] fragment production is clearly seen in the respective curves. Features occurring at the same energy in several of the curves indicate that these are due to a common progenitor, particularly the [Formula: see text] complex. The appearance of different fragmentation processes accounts for the onset-type structure found in some of the fragment-ion curves.

Ionization and dissociative ionization of CO2 by electron impact

1977 ◽  
Vol 55 (21) ◽  
pp. 1889-1897 ◽  
Author(s):  
N. Bussières ◽  
P. Marmet
Keyword(s):  
Kinetic Energy ◽  
Electron Impact ◽  
Signal To Noise Ratio ◽  
Ion Pair ◽  
Pair Formation ◽  
Negative Ion ◽  
High Signal ◽  
Signal To Noise ◽  
Fragment Ions ◽  
Zero Kinetic Energy

Using a very sensitive apparatus with a high signal-to-noise ratio, new structures are observed in the ionization curve of CO2 by electron impact in the first 10 V above the ionization threshold. Neutral and negative ion levels are observed and related to npσu and npπu series converging to Ā, [Formula: see text], and [Formula: see text] levels of CO2+. Data for the fragment ions CO+, O+, and C+ are also presented; it is shown that they can be formed with zero kinetic energy. No ion pair formation can be detected at threshold.

Metastable yield of argon between 23 and 37 eV by electron impact

1979 ◽  
Vol 57 (10) ◽  
pp. 1624-1633 ◽  
Author(s):  
P. Marchand ◽  
J. Cardinal
Keyword(s):  
Electron Impact ◽  
Excited States ◽  
Signal To Noise Ratio ◽  
Negative Ion ◽  
Photon Yield ◽  
Large Signal ◽  
Signal To Noise ◽  
Monoenergetic Electron ◽  
Yield Curves ◽  
Noise Ratio

The metastable yield of argon excited by monoenergetic electron impact has been measured between 23 and 37 eV. Thanks to a large signal-to-noise ratio, many very small structures have been detected superimposed on the metastable continuum and are attributed to Ar− negative-ion states and to highly excited states of Ar. The results are compared with broadband photon yield curves and electroionization curves.

Anti-Vibration Sub Allows A Very High Signal-To-Noise Ratio And Improves Borehole Quality

2013 ◽  
Author(s):  
Paul Christian Bates ◽  
Chakib Bouziane ◽  
Denise Nicholl ◽  
Reina Teelken ◽  
Mohammed Zuki Bin Bidi ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Very High

Excited states of HI and DI and their negative ions between 10 and 20 eV

1988 ◽  
Vol 66 (7) ◽  
pp. 564-569
Author(s):  
P. Marmet ◽  
Hamid Nasrallah
Keyword(s):  
Excited States ◽  
Signal To Noise Ratio ◽  
Rydberg States ◽  
Negative Ions ◽  
Ionization Efficiency ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio ◽  
The Impact ◽  
Very High

The ionization-efficiency curves of HI and DI, obtained by the impact of monoenergetic electrons between 10 and 20 eV, are presented with a very high signal-to-noise ratio. Several new Rydberg states between the 2Π(3/2) and 2Π(1/2) limits and also below the 2Σ+ limit have been identified. Also, the first two 6s and 6p Rydberg levels with configuration (5sσ)1(5pσ)2(5pπ)4nlλ have been observed at 17.3 and 18.6 eV, respectively. The results obtained in DI confirm the structures observed in HI.

scholarly journals The Most Efficient Tool for very High Resolution and very High Signal to Noise Ratio Spectral Observation of Stars

1988 ◽  
Vol 132 ◽  
pp. 15-21
Author(s):  
S. Y. Jiang
Keyword(s):  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Spectral Observation ◽  
Resolving Power ◽  
High Signal ◽  
Large Telescope ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Very High ◽  
Light Efficiency

Today even for the most efficient spectrograph combined with a large telescope the light efficiency is only about 0.01 to 0.1 for spectral resolving power R larger than 10000 in optical wavelength band (OWB). Consequently for a very high signal to noise ratio spectral observation of rather bright stars still needs very large telescope. The main reason is that there are too many optical surface with rather low light efficiency and serious light loss at the limited slit width. In this paper we suggest a very high efficiency telescope-spectrograph system which will give an overall light efficiency varied from 0.21 at 400 nm to 0.44 at 700 nm, four fold higher than before. Using this system for R = 100000, S/N larger than 100 the limiting magnitude will be about 15.

A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

2020 ◽  
Vol 64 (1-4) ◽  
pp. 951-958
Author(s):  
Tianhao Liu ◽  
Yu Jin ◽  
Cuixiang Pei ◽  
Jie Han ◽  
Zhenmao Chen
Keyword(s):  
Power Plants ◽  
Signal To Noise Ratio ◽  
Small Diameter ◽  
Performance Testing ◽  
Guided Wave ◽  
High Signal ◽  
Receiver Coil ◽  
Signal To Noise ◽  
Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

Narrow-frequency sharp-angular filters using all-dielectric cascaded meta-gratings

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3443-3450 ◽  
Author(s):  
Wei-Nan Liu ◽  
Rui Chen ◽  
Wei-Yi Shi ◽  
Ke-Bo Zeng ◽  
Fu-Li Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Signal To Noise Ratio ◽  
Incident Angle ◽  
Design Strategy ◽  
Transmission Peak ◽  
High Signal ◽  
Waveguide Array ◽  
Signal To Noise ◽  
Center Wavelength ◽  
Noise Ratio

AbstractSelective transmission or filtering always responds to either frequency or incident angle, so as hardly to maximize signal-to-noise ratio in communication, detection and sensing. Here, we propose compact meta-filters of narrow-frequency sharp-angular transmission peak along with broad omnidirectional reflection sidebands, in all-dielectric cascaded subwavelength meta-gratings. The inherent collective resonance of waveguide-array modes and thin film approximation of meta-grating are employed as the design strategy. A unity transmission peak, locating at the incident angle of 44.4° and the center wavelength of 1550 nm, is demonstrated in a silicon meta-filter consisting of two-layer silicon rectangular meta-grating. These findings provide possibilities in cascaded meta-gratings spectroscopic design and alternative utilities for high signal-to-noise ratio applications in focus-free spatial filtering and anti-noise systems in telecommunications.

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