Ion Dynamics in Low Frequency RF Plasmas

1983 ◽  
Vol 29 ◽  
Author(s):  
Richard A. Gottscho ◽  
Daniel L. Flamm ◽  
Randolph H. Burton ◽  
Vincent M. Donnelly
Keyword(s):  
Plasma Etching ◽  
Low Frequency ◽  
Ion Concentration ◽  
Ion Dynamics ◽  
Applied Potential ◽  
Time Resolved ◽  
Rf Plasmas ◽  
Use Of Time ◽  
Concentration Time ◽  
State Ionic

ABSTRACTWe describe the use of time-resolved laser-induced fluorescence (TRLIF) and plasma-induced emission (PIE) spectroscopy in studying the dynamics of ion transport, formation, and loss in low frequency RF plasmas, used in plasma etching and deposition. N2+ and Cl2+ ions formed in N2, Cl2, and N2/Cl2 discharges were monitored as a function of both position between the electrodes and magnitude of the applied rf potential. In the discharge center, TRLIF was used to measure ground state ionic lifetimes. In N2/Cl2 mixtures, N2+ was found to charge exchange rapidly with Cl2 and Cl to form Cl2+ and Cl+. In the electrode sheaths, the ion response to the applied potential was evident from periodic depletion of the ion concentration as a result of acceleration by the field. From the spatial variation in the ion concentration time dependence, we deduce that the sheaths expand and contract with the same period as the applied potential.

scholarly journals Back to the Future: Genetically Encoded Fluorescent Proteins as Inert Tracers of the Intracellular Environment

2020 ◽  
Vol 21 (11) ◽  
pp. 4164 ◽  
Author(s):  
Francesco Cardarelli
Keyword(s):  
Fluorescent Proteins ◽  
Ion Concentration ◽  
Fluorescence Labeling ◽  
Living Matter ◽  
Time Resolved ◽  
Intracellular Environment ◽  
Use Of Time ◽  
Cellular Environment ◽  
Molecular Components ◽  
Microscopy Techniques

Over the past decades, the discovery and development of genetically encoded fluorescent proteins (FPs) has brought a revolution into our ability to study biologic phenomena directly within living matter. First, FPs enabled fluorescence-labeling of a variety of molecules of interest to study their localization, interactions and dynamic behavior at various scales—from cells to whole organisms/animals. Then, rationally engineered FP-based sensors facilitated the measurement of physicochemical parameters of living matter—especially at the intracellular level, such as ion concentration, temperature, viscosity, pressure, etc. In addition, FPs were exploited as inert tracers of the intracellular environment in which they are expressed. This oft-neglected role is made possible by two distinctive features of FPs: (i) the quite null, unspecific interactions of their characteristic β-barrel structure with the molecular components of the cellular environment; and (ii) their compatibility with the use of time-resolved fluorescence-based optical microscopy techniques. This review seeks to highlight the potential of such unique combinations of properties and report on the most significative and original applications (and related advancements of knowledge) produced to date. It is envisioned that the use of FPs as inert tracers of living matter structural organization holds a potential for several lines of further development in the next future, discussed in the last section of the review, which in turn can lead to new breakthroughs in bioimaging.

Ion dynamics of rf plasmas and plasma sheaths: A time‐resolved spectroscopic study

1984 ◽  
Vol 55 (7) ◽  
pp. 2707-2714 ◽  
Author(s):  
Richard A. Gottscho ◽  
Randolph H. Burton ◽  
Daniel L. Flamm ◽  
Vincent M. Donnelly ◽  
Glenn P. Davis
Keyword(s):  
Spectroscopic Study ◽  
Ion Dynamics ◽  
Time Resolved ◽  
Rf Plasmas ◽  
Plasma Sheaths

Time Resolved Diagnostics of RF Plasmas: a Fluid Model for ion Concentrations in the Sheath

1984 ◽  
Vol 38 ◽  
Author(s):  
Richard A. Gottscho
Keyword(s):  
Impact Ionization ◽  
Fluid Model ◽  
Formation Rate ◽  
Low Frequency ◽  
Quantitative Agreement ◽  
Ion Concentration ◽  
Time Resolved ◽  
Ion Concentrations ◽  
Computational Optimization ◽  
Spectrally Resolved

AbstractA one-dimensional fluid model is presented for time-dependent ion concentrations in chlorine containing discharges. The ion formation rate is determined from experimental plasma-induced emission intensities. The local field is estimated from spectrally resolved laser-induced fluorescence data obtained in similar, BCl3 discharges. Quantitative agreement with experiment is obtained implying that the basic assumptions in the model are valid: (1) ground state ions in the sheath are formed predominantly by electron-impact ionization; (2) Cl2+ ion motion is mobilitylimited by charge exchange collisions with Cl2 neutrals; (3) the degree of Cl2 dissociation is ∼. 65% at a power density of 1.8 W cm−3; (4) the ion concentration near the electrode is spatially uniform throughout most of the rf cycle; and (5) there are two times during a low frequency rf cycle when ions experience a strong extraction force.Semi-empirical models like the one described here should be useful in computational optimization of plasma processes such as etching and deposition, which are in wicre-spread use throughout the microelectronics industry.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

Determination of Carbon Content in Steel Using Laser-Induced Breakdown Spectroscopy

1992 ◽  
Vol 46 (9) ◽  
pp. 1382-1387 ◽  
Author(s):  
J. A. Aguilera ◽  
C. Aragón ◽  
J. Campos
Keyword(s):  
Carbon Content ◽  
Matrix Effects ◽  
Sample Surface ◽  
Nitrogen Atmosphere ◽  
Laser Induced Breakdown Spectroscopy ◽  
Time Resolved ◽  
Breakdown Spectroscopy ◽  
Use Of Time ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy has been used to determine carbon content in steel. The plasma was formed by focusing a Nd:YAG laser on the sample surface. With the use of time-resolved spectroscopy and generation of the plasma in nitrogen atmosphere, a precision of 1.6% and a detection limit of 65 ppm have been obtained. These values are similar to those of other accurate conventional techniques. Matrix effects for the studied steels are reduced to a small slope difference between the calibration curves for stainless and nonstainless steels.

scholarly journals Theta activity paradoxically boosts gamma and ripple frequency sensitivity in prefrontal interneurons

2021 ◽  
Vol 118 (51) ◽  
pp. e2114549118
Author(s):  
Ricardo Martins Merino ◽  
Carolina Leon-Pinzon ◽  
Walter Stühmer ◽  
Martin Möck ◽  
Jochen F. Staiger ◽  
...  
Keyword(s):  
Low Frequency ◽  
Gamma Oscillations ◽  
Brain State ◽  
Gabaergic Interneurons ◽  
Time Resolved ◽  
Cortical Rhythms ◽  
Brain States ◽  
Fast Spiking ◽  
Fast Oscillations ◽  
Cross Frequency Coupling

Fast oscillations in cortical circuits critically depend on GABAergic interneurons. Which interneuron types and populations can drive different cortical rhythms, however, remains unresolved and may depend on brain state. Here, we measured the sensitivity of different GABAergic interneurons in prefrontal cortex under conditions mimicking distinct brain states. While fast-spiking neurons always exhibited a wide bandwidth of around 400 Hz, the response properties of spike-frequency adapting interneurons switched with the background input’s statistics. Slowly fluctuating background activity, as typical for sleep or quiet wakefulness, dramatically boosted the neurons’ sensitivity to gamma and ripple frequencies. We developed a time-resolved dynamic gain analysis and revealed rapid sensitivity modulations that enable neurons to periodically boost gamma oscillations and ripples during specific phases of ongoing low-frequency oscillations. This mechanism predicts these prefrontal interneurons to be exquisitely sensitive to high-frequency ripples, especially during brain states characterized by slow rhythms, and to contribute substantially to theta-gamma cross-frequency coupling.

scholarly journals The biochemical resolving power of fluorescence lifetime imaging

2021 ◽  
Author(s):  
Andrew L. Trinh ◽  
Alessandro Esposito
Keyword(s):  
Fluorescence Lifetime ◽  
Resolving Power ◽  
Fluorescence Lifetime Imaging ◽  
Time Resolved ◽  
Instrument Response Function ◽  
Lifetime Imaging ◽  
Use Of Time ◽  
Single Living Cells ◽  
Microscopy Techniques

AbstractA deeper understanding of spatial resolution in microscopy fostered a technological revolution that is now permitting us to investigate the structure of the cell with nanometer resolution. Although fluorescence microscopy techniques enable scientists to investigate both the structure and biochemistry of the cell, the biochemical resolving power of a microscope is a physical quantity that is not well-defined or studied. To overcome this limitation, we carried out a theoretical investigation of the biochemical resolving power in fluorescence lifetime imaging microscopy, one of the most effective tools to investigate biochemistry in single living cells. With the theoretical analysis of information theory and Monte Carlo simulations, we describe how the ‘biochemical resolving power’ in time-resolved sensing depends on instrument specifications. We unravel common misunderstandings on the role of the instrument response function and provide theoretical insights that have significant practical implications in the design and use of time-resolved instrumentation.

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