Predissociation in the spectrum of OH; the vibrational and rotational intensity distribution in flames

1951 ◽  
Vol 208 (1092) ◽  
pp. 63-75 ◽  
Keyword(s):  
Reaction Zone ◽  
Intensity Distribution ◽  
Atmospheric Pressure ◽  
Low Pressure ◽  
The Other ◽  
Spin Component ◽  
Reverse Process ◽  
Free Atoms

In the main 3064 Å system of OH higher rotational levels of bands with v' = 1 and all levels with v' ≥ 2 are affected by a weak predissociation. One spin component of the 2Ʃ + levels is more strongly affected than the other. Of the three molecular states, 4II, 4Ʃ ¯ and 2Ʃ ¯ which could conceivably cause the predissociation, only the 2Ʃ ¯ could produce this effect. The predissociation is observed in the OH bands from a discharge and from the reaction zone of an oxy-acetylene flame at low pressure, and also to some extent in a flame at atmospheric pressure. The predissociation, and its reverse process, a ‘pre-association’, may also affect the vibrational intensity distribution if there is departure from equilibrium. Striking anomalies of this type in hydrogen flames are interpreted in this way. For flames at 1 atm. pressure there appears to be an excess of free atoms in the flame, and at low-pressure emission of radiation from the flame disturbs the equilibrium.

The mechanism of formation of OH, CH and HCO in flame spectra, using deuterium as tracer

1953 ◽  
Vol 218 (1132) ◽  
pp. 60-69 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
Atomic Hydrogen ◽  
Premixed Flames ◽  
Low Pressure ◽  
Chemical Processes ◽  
Similar Technique ◽  
Mechanism Of Formation ◽  
Secondary Reactions ◽  
Free Atoms

Deuterium has been used as a tracer in studies of the spectra of premixed flames of hydrogen, acetylene and oxygen, both at atmospheric pressure and at very low pressure. A similar technique has also been used with the ‘flames’ due to the reactions of free atoms; these experiments indicate that the exchange between atomic hydrogen and acetylene is not an appreciable factor in producing the observed spectra. The radiation from excited CH and HCO and part of that from OH appears to result from chemical processes, but the radicals are formed by some secondary reactions, not directly in the breakdown of the hydrocarbon. Possible reactions are discussed; excited CH is probably formed from C 2 + OH and excited OH from CH + O 2 .

Excitation of spectra of OH in hydrogen flames and its relation to excess concentrations of free atoms

1958 ◽  
Vol 245 (1240) ◽  
pp. 84-92 ◽  
Keyword(s):  
Reaction Zone ◽  
Intensity Distribution ◽  
Selective Excitation ◽  
Strong Excitation ◽  
Free Atoms

Measurements have been made of the rotational and vibrational intensity distribution of OH bands in oxygen + hydrogen + nitrogen flames. Simultaneous observations have been made of the strength of Na and Li lines and their variation with height in the flame. The anomalously strong excitation of OH bands with v ' = 2 and 3 is accompanied by selective excitation of the f 1 spin levels of the 2 ∑ + state. This confirms that the anomaly results from an inverse predissociation, associated with an excess of free atoms in the flame gases. This excess is most important for the cooler flames and near the base of these flames. There is also strong excitation of the (0, 0) band of OH near the reaction zone and the mechanism for this is briefly discussed.

Predictions of Current Attachment at Thermionic Cathode for TIG Arcs

2008 ◽  
Vol 580-582 ◽  
pp. 319-322 ◽  
Author(s):  
Manabu Tanaka ◽  
Kentaro Yamamoto ◽  
Tashiro Shinichi ◽  
John J. Lowke
Keyword(s):  
Melting Point ◽  
Work Function ◽  
Atmospheric Pressure ◽  
The Other ◽  
Numerical Calculations ◽  
Maximum Temperature ◽  
Arc Plasma ◽  
Melting Points ◽  
Thermionic Cathode ◽  
Uniform Current

Study of current attachment at thermionic cathode for TIG arc at atmospheric pressure is attempted from numerical calculations of arc-electrodes unified model. The calculations show that the maximum temperature of arc plasma close to the cathode tip for W-2% ThO2 reaches 19,000 K and it is the highest value in comparison with the other temperatures for W-2% La2O3 and W-2% CeO2, because the current attachment at the cathode tip is constricted by a centralized limitation of liquid area of ThO2 due to its higher melting point. The calculations also show that, in cases of W- 2% La2O3 and W-2% CeO2, the liquid areas of La2O3 and Ce2O3 are widely expanded at the cathode tip due to their lower melting points and then produce uniform current attachments at the cathode. It is concluded that the current attachment at thermionic cathode is strongly dependent on work function, melting point and Richardson constant of emitter materials.

scholarly journals Experimental study on the effect of spray cone angle on the characteristics of horizontal jet spray flame under sub-atmospheric pressure

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2941-2952 ◽  
Author(s):  
Kai Xie ◽  
Xingqi Qiu ◽  
Yunjing Cui ◽  
Jianxin Wang
Keyword(s):  
Atmospheric Pressure ◽  
Cone Angle ◽  
Flame Temperature ◽  
Normal Pressure ◽  
Low Pressure ◽  
Dimensionless Temperature ◽  
Thermal Imager ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Matlab Programming

The burning state of a plateau environment is attracting more and more attention. In this paper, in order to have a deeper scientific understanding of diesel spray combustion and the characteristics of a flame under different spray cone angles in a plateau environment, experiments were carried out in a low pressure chamber. The flame morphology was recorded by a high speed video instrument, and the temperature change was recorded by a thermal imager and thermocouples. The MATLAB programming was used to process the video image of the flame, and the probability of its binarization was calculated. The results indicate that the flame becomes longer and wider under different pressures with the same spray angle. The variation is more pronounced at a smaller spray taper angle. The flame uplifted height characteristic is mainly negatively related to the atmospheric pressure. According to the normalized flame temperature and the dimensionless horizontal projection, the length can be divided into three regions. In the region of buoyancy flame, the dimensionless temperature varies with sub-atmospheric pressure more than with normal pressure. In addition, under different spray cone angle conditions, the law of variation in the normalized flame temperature under sub-atmospheric pressure is exactly opposite to that under normal pressure. This study is of great significance to the scientific research on flames in a low pressure environment, and the design of different fuel nozzles for application in a plateau environment.

Personalistic Organicism: Paradox or Paradigm?

1994 ◽  
Vol 36 ◽  
pp. 59-73 ◽  
Author(s):  
Frederick Ferré
Keyword(s):  
World View ◽  
Personal Values ◽  
The Other ◽  
The Earth ◽  
Free Atoms

Many environmental thinkers are torn in two opposing directions at once. For good reasons we are appalled by the damage that has been done to the earth by the ethos of heedless anthropocentric individualism, which has achieved its colossal feats of exploitation, encouraged to selfishness by its world view—of relation-free atoms—while chanting ‘reduction’ as its mantra. But also for good reasons we are repelled, at the other extreme, by environmentally correct images of mindless biocentric collectivisms in which precious personal values are overridden for the good of some healthy beehive ‘whole’.

scholarly journals Transfer of POCl3 diffusion processes from atmospheric pressure to high throughput low pressure

2018 ◽  
Author(s):  
Sabrina Lohmüller (née Werner) ◽  
Stefan Schmidt ◽  
Elmar Lohmüller ◽  
Alexander Piechulla ◽  
Udo Belledin ◽  
...  
Keyword(s):  
High Throughput ◽  
Atmospheric Pressure ◽  
Diffusion Processes ◽  
Low Pressure
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