Theory for diffusion-limited oscillating chemical reactions

In this work we use Thompson's renormalization group method to treat diffusion limited chemical reactions A + B →0 (inert product), with unequal initial concentrations of the two species, by considering ρ A (0)≪ρ B (0). For d≤2, we obtain stretched exponential decaying of the specie A, which is in agreement with rigorous result of Bramson and Lebowitz. For d>2, we obtain simple exponential decaying of the specie A.

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An analysis of diffusion-limited first and second order chemical reactions in a turbulent shear layer

10.2514/6.1974-593 ◽

1974 ◽

Cited By ~ 4

Author(s):

I. ALBER ◽

R. BATT

Keyword(s):

Shear Layer ◽

Chemical Reactions ◽

Second Order ◽

Turbulent Shear ◽

Turbulent Shear Layer ◽

Diffusion Limited

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UNIFIED TREATMENT OF A+B→0 AND A+A→0 CHEMICAL REACTIONS THROUGH THOMPSON'S APPROACH

Modern Physics Letters B ◽

10.1142/s0217984999001020 ◽

1999 ◽

Vol 13 (22n23) ◽

pp. 829-836 ◽

Cited By ~ 10

Author(s):

CLÁUDIO NASSIF ◽

P. R. SILVA

Keyword(s):

Chemical Reactions ◽

Mean Field ◽

Reaction Rates ◽

Rigorous Results ◽

Critical Dimensions ◽

Long Wavelength ◽

Diffusion Limited ◽

First Case ◽

Long Time ◽

The Mean

In this work we propose an action to describe diffusion limited chemical reactions belonging to various classes of universality. This action is treated through Thompson's approach and can encompass both cases where we have segregation as in the A + B →0 reaction, as well as the simplest one, namely the A + A →0 reaction. Our results for long-time and long-wavelength behaviors of the species concentrations and reaction rates agree with exact results of Peliti for A + A →0 reaction and rigorous results of Bramson and Lebowitz for A + B →0 reaction, with equal initial concentrations. The different classes of universality are reflected by the obtained upper critical dimensions varying continuously from d c =2 in the first case to d c =4 in the last one. Just as at the upper critical dimensions, we find universal logarithmic corrections to the mean field behavior.

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Surface reactions observed by photoemission electron microscopy (PEEM)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121831 ◽

1992 ◽

Vol 50 (1) ◽

pp. 286-287

Author(s):

H.H. Rotermund

Keyword(s):

Electron Microscopy ◽

Electron Microscope ◽

Work Function ◽

Chemical Reactions ◽

Reaction Diffusion ◽

Dynamic Processes ◽

Clean Surface ◽

Crystal Surfaces ◽

Single Crystal Surfaces ◽

Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

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Microwaves: Application in Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158248 ◽

1990 ◽

Vol 48 (3) ◽

pp. 140-141

Author(s):

Anthony S-Y Leong ◽

David W Gove

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Chemical Reactions ◽

Electromagnetic Waves ◽

Tissue Fixation ◽

Primary Method ◽

Dipolar Molecules ◽

Wide Range ◽

Time Required ◽

Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

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