Laser Investigations of the Dynamics of Molecule-Surface Interaction

1983 ◽  
Vol 29 ◽  
Author(s):  
J. Hager ◽  
H. Walther
Keyword(s):  
Energy Distribution ◽  
Surface Temperature ◽  
Velocity Distribution ◽  
Average Velocity ◽  
Boltzmann Distribution ◽  
Rotational Energy ◽  
Solid Surfaces ◽  
Measured Velocity ◽  
Small Influence ◽  
Molecule Surface

ABSTRACTThe internal energy distribution of NO molecules scattered from different solid surfaces (Pt(111), graphite, and Pt(111) covered with various adlayers) was investigated by the laser-induced fluorescence method. In the case of the NO/graphite system, moreover, the velocity distribution of the scattered molecules could be measured in a time-offlight experiment. The rotational energy distribution, which can always be described as a Boltzmann distribution, exhibits only partial accommodation to the surface temperature for all surfaces investigated. The measurements of the velocity of the NO molecules scattered from the graphite surface show only a small influence of the surface temperature on the average velocity and on the velocity distribution. Furthermore, the measured velocity distribution is independent of the final rotational state of the scattered molecules. On the basis of these results, a rather complete description of the behavior of the NO molecules during the scattering process can be presented.

Experimental Characterization of Slug Flow Velocity Distribution in Two Phase Pipe Flow

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Velocity Distribution ◽  
Slug Flow ◽  
Two Phase ◽  
Significant Drop ◽  
Horizontal Pipe ◽  
Measured Velocity ◽  
Air Bubble ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching

This paper presents an experimental study of gas-liquid slug flow inside a horizontal pipe. The influence of air bubble passage on liquid flow is characterized using Particle Image Velocimetry (PIV) combined with Refractive Index Matching (RIM) and fluorescent tracers. A physical insight into the velocity distribution within slug flow is presented. It was observed that the slug flow significantly influences the velocity profile in the liquid film. Measured velocity distributions also revealed a significant drop in the velocity magnitude immediately upstream of the slug nose. These findings aim to aid an understanding of the mechanism of solid transportation in slug flows.

scholarly journals Emission-Line Profiles in Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 267-269
Author(s):  
Donald E. Osterbrock
Keyword(s):  
Velocity Distribution ◽  
Emission Line ◽  
Observational Data ◽  
Planetary Nebulae ◽  
Line Profiles ◽  
Measured Velocity ◽  
Hydrodynamical Models ◽  
Internal Velocity ◽  
First Time

This research was undertaken with the idea of measuring as accurately as possible the internal-velocity distribution in planetary nebulae, in order to compare the observational measurements with hydrodynamical models of expanding nebulae. Much of the work was done in collaboration with J. S. Miller and D.W. Weedman. All the observational data were obtained photographically with the Coudé spectrograph of the 100-inch telescope at Mt. Wilson, using an image rotator, a 900 line/mm grating, and an F/5-2 camera, giving a dispersion of about 4 Å/mm in the blue and about 6 Å/mm in the red. The measured velocity resolution is approximately 5–6 km/sec. The data for five nebulae have been published (Osterbrock et al., 1966) while data for three more, NGC 2392, NGC 3242, and IC 418 are discussed here for the first time.

Investigation of the Submerged Depth of Aeration Impellers in an Oxidation Ditch by Numerical Simulation

2012 ◽  
Vol 178-181 ◽  
pp. 429-432
Author(s):  
Y. L. Liu ◽  
B. Lv ◽  
W.L. Wei
Keyword(s):  
Numerical Simulation ◽  
Velocity Distribution ◽  
Average Velocity ◽  
Sewage Treatment ◽  
Processing System ◽  
Simulation Method ◽  
Velocity Fields ◽  
Oxidation Ditch ◽  
Depth Direction ◽  
Sewage Treatment System

In this paper, the flow structure of the oxidation ditch was studied using numerical simulation method and different submerged depth of aeration impellers. The computed velocity fields were analyzed, which shows that under the same conditions, and by using the optimal submerged depth the average velocity of the flow in oxidation ditch is increased and the velocity near-bottom has increased significantly. The results of comparisons show that the velocity distribution is more uniform along the depth direction, and that the flow velocity distribution structure can prevent sludge from settling in the oxidation ditch processing system at the submergence ratio called the optimal submergence ratio, which helps to improve the efficiency of oxidation ditch sewage treatment system.

Photodissociation of the NO dimer: rotational energy distribution and alignment of the NO(B 2Π) fragments

1992 ◽  
Vol 190 (1-2) ◽  
pp. 135-140 ◽  
Author(s):  
Yukito Naitoh ◽  
Yo Fujimura ◽  
Okitsugu Kajimoto ◽  
Kenji Honma
Keyword(s):  
Energy Distribution ◽  
Rotational Energy

scholarly journals Rotational Energy Distribution of the CsH Formed in the Reaction Between Cs(7P1/2) and H2

1986 ◽  
Vol 5 (6) ◽  
pp. 367-373 ◽  
Author(s):  
J. P. Visticot ◽  
M. Ferray ◽  
P. D'Oliveira ◽  
B. Sayer
Keyword(s):  
Energy Distribution ◽  
Hydrogen Molecule ◽  
Rotational Energy ◽  
Cesium Atom ◽  
Thermal Distribution ◽  
A Cell ◽  
Rotational Distribution

The nascent rotational distribution of the CsH molecules formed by the reaction between a cesium atom in the 7P1/2 state and a hydrogen molecule has been measured in a cell. A thermal distribution at the temperature of the cell is reported.

scholarly journals The exchange of energy between gas atoms and solid surfaces

1930 ◽  
Vol 129 (809) ◽  
pp. 146-161 ◽  
Keyword(s):  
Temperature Jump ◽  
Average Energy ◽  
Accommodation Coefficient ◽  
Rotational Energy ◽  
Solid Surfaces ◽  
Translational Energy ◽  
Gas Molecules ◽  
The Difference

If gas molecules with average energy corresponding to a given temperature strike the surface of a solid at a different temperature, the average energy of the gas molecules leaving the surface does not in general correspond to the temperature of the solid but depends also on their average energy before staking it. In order to exclude complications due to the transfer of rotational energy we shall consider only monatomic gases. Let the average translational energy of the molecules before striking the surface at temperature T 2 correspond to a temperature T 1 , and let the average translational energy of the molecules after leaving the surface correspond to a temperature T 2 ' (see fig. 1). Modifying slightly a suggestion made by Maxwell* in a different connection, Smoluchowski assumed that the change in the temperature of the gas molecules brought about by striking the surface is proportional to the difference between the temperature of the surface and that of the gas molecules before striking it ; that is, that T 2 - T 1 = a , (T 2 - T 1 ). (1) The constant of proportionality a was later called the accommodation coefficient by Knudsen. Smoluchowski applied this idea to explain the so-called temperature jump at the surface of a solid.

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