scholarly journals The reaction of atomic hydrogen with hydrazine

1940 ◽  
Vol 175 (961) ◽  
pp. 164-186 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Atomic Hydrogen ◽  
Ammonia Molecule ◽  
Para Hydrogen ◽  
Hydrogen Atoms ◽  
Stationary Concentration ◽  
Essential Step ◽  
Photochemical Decomposition ◽  
The Subject

The reason for studying the reaction of hydrogen atoms with hydrazine is that a controversy has arisen in attempting to elucidate the mechanism of the photochemical decomposition of ammonia. It has been generally agreed that the ammonia molecule is decomposed to a hydrogen atom and an amine radical when it absorbs light around 2000° A. Presuming that the atomic hydrogen combines on the walls or in the gas phase it is possible to calculate what its stationary concentration ought to be under any given set of conditions. If, however, the stationary concentration is actually measured by using para-hydrogen as a detector, as was done by Farkas and Harteck (1934), it is found that the measured value is lower than the value calculated from the above assumptions. A number of suggestions, discussed in detail in the following paper, were made to explain this discrepancy, and among the most reasonable was that of Mund and van Tiggelen (1937) who suggested that the hydrazine known to be formed in the system removed such atoms more rapidly than would occur in the ordinary course of events. The result of their suggestion was the invention of elaborate schemes to explain the mechanism of the ammonia photolysis. As a further essential step in the ammonia problem it therefore seemed necessary to measure the efficiency of the reaction between hydrogen atoms and hydrazine. At the same time further information was also desirable about the photochemistry of hydrazine itself. This paper will therefore be concerned with this aspect of the subject. The results will then be discussed in the following paper together with a number of new experiments on ammonia in order that the mechanism of the ammonia reaction may be more fully established.

scholarly journals The photolysis of ammonia

1940 ◽  
Vol 175 (961) ◽  
pp. 187-207 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Preceding Paper ◽  
Ammonia Molecule ◽  
Experimental Techniques ◽  
Hydrogen Atoms ◽  
Atom Concentration ◽  
Important Discrepancy

It has been shown in the preceding paper that the hypothesis that hydrazine is responsible for the anomalously low hydrogen atom concentration in the decomposition of ammonia must be abandoned. In order to explain this important discrepancy some new experimental techniques require to be developed which will settle the matter without appeal to further hypotheses. There are two general explanations of the discrepancy: (1) the hydrogen atoms are not produced as fast as that calculated on the assumption that every ammonia molecule absorbing a quantum necessarily decomposes, (2) that some entity not yet recognized removes hydrogen atoms at a rate faster than that at which they normally recombine. In this paper methods will be described in which these two problems are solved, and finally there is a discussion of the photochemistry of ammonia in the light of the new results obtained during these experiments.

A study of the properties of hydrogen films on tungsten by the method of contact potentials

1937 ◽  
Vol 33 (3) ◽  
pp. 394-402 ◽  
Author(s):  
R. C. L. Bosworth
Keyword(s):  
Dipole Moment ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Atomic Hydrogen ◽  
The Other ◽  
Condensation Coefficient ◽  
Effective Dipole Moment ◽  
Tungsten Atom ◽  
Contact Potential ◽  
Hydrogen Molecules

In a study of the properties of hydrogen on tungsten by the method of contact potentials the following points have been established:(1) The contact potential of a 92% covered surface of hydrogen on tungsten against bare tungsten is 1·04 V., and the Richardson constants for such a surface are, approximately,A = 30, b = 5·60 V.(2) A film of deuterium is 20 m V. positive relative to a similar hydrogen film.(3) Over the range of temperatures and pressures used by Bryce in a study of the production of atomic hydrogen the films are nearly saturated, so that the production of atomic hydrogen is primarily due to a molecule striking a bare tungsten atom, one atom being adsorbed and the other going into the gas phase.(4)The condensation coefficient for hydrogen molecules on cold tungsten is 0·01.(5) The effective dipole moment of each hydrogen atom on the surface is −0·42 Debye unit and is independent of the fraction of the surface covered.

The kinetics of the interaction of atomic hydrogen with olefines. V. Results obtained for a further series of compounds

1950 ◽  
Vol 202 (1069) ◽  
pp. 181-202 ◽  
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Alkyl Radicals ◽  
Kinetics Of ◽  
Interesting Generalization

In this paper the efficiency of interaction of a hydrogen atom with a series of olefines has been determined, the olefines being members of the series obtained by progressively replacing the hydrogen atoms of ethylene by methyl radicals. The interesting generalization which emerges from this is that the efficiency of interaction does not vary very much with the nature of the alkyl substituents in the molecule, and calculations involving the heats of addition of a hydrogen atom to a double bond confirm this generalization. The data presented here are discussed critically in relation to information available on the reaction of CCl 3 radicals with olefines and of alkyl radicals with olefines, complete general agreement being demonstrated.

The origin of light emission in the atomic hydrogen—acetylene flame

1964 ◽  
Vol 282 (1389) ◽  
pp. 275-282 ◽  
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen ◽  
Atomic Oxygen ◽  
Light Emission ◽  
Reactive Intermediates ◽  
Hydrogen Atoms ◽  
Electronically Excited ◽  
Catalytic Recombination ◽  
Oxygen Atoms

Acetylene catalyzes the gas phase recombination of hydrogen atoms, and frequently the reaction is accompanied by a bright flame. It is shown that the light emission is not the result of the catalytic recombination, but is caused by traces of water in the hydrogen. The possible reactive intermediates, OH, HO 2 and atomic oxygen, have been individually generated and added to the mixture of hydrogen atoms and acetylene. Only oxygen atoms are effective in causing luminescence. Hydrogen atoms are not necessary for light emission, but they do alter the spectrum somewhat. Two different mechanisms for the formation of electronically excited C 2 are required. The mechanism for the reaction of atomic oxygen with acetylene is discussed.

scholarly journals The kinetics of the interaction of atomic hydrogen with olefines III. Theory and technique involved in the use of the oxides of molybdenum and tungsten as hydrogen atom removers

1949 ◽  
Vol 196 (1047) ◽  
pp. 479-493 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Molybdenum Oxide ◽  
Atomic Hydrogen ◽  
Colorimetric Method ◽  
Oxide Surface ◽  
Hydrogen Atoms ◽  
Alkyl Radicals ◽  
Kinetics Of ◽  
And Tungsten

The colorimetric method of estimating the rate of addition of hydrogen atoms to the oxides of molybdenum and tungsten is discussed in detail. It is also shown that alkyl radicals are efficiently removed by molybdenum oxide, and allowance is made for the effect of their presence on the blueing rate of the oxide surface. The method of evaluating collision efficiencies from the data obtained is indicated in full, and the construction and operation of a calculator to assist in the computation is described.

Hydrogen atom attachment to histidine and tryptophan containing peptides in the gas phase

2019 ◽  
Vol 21 (22) ◽  
pp. 11633-11641 ◽  
Author(s):  
Daiki Asakawa ◽  
Hidenori Takahashi ◽  
Shinichi Iwamoto ◽  
Koichi Tanaka
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Bond Cleavage ◽  
Tryptophan Residue ◽  
Side Chains ◽  
Hydrogen Atoms ◽  
Fragment Ions ◽  
Gas Phase Fragmentation

In this study, we focus on the gas-phase fragmentation induced by the attachment of hydrogen atoms to the histidine and tryptophan residue side-chains in the peptide that provides the fragment ions due to Cα–Cβ bond cleavage.

scholarly journals The kinetics of the interaction of atomic hydrogen with olefines II. Diffusion theory

1949 ◽  
Vol 196 (1047) ◽  
pp. 466-478 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Diffusion Theory ◽  
One Dimension ◽  
Hydrogen Atoms ◽  
Collision Efficiency ◽  
Atom Concentration ◽  
Differential Diffusion ◽  
Set Up ◽  
Kinetics Of

In this paper, a system is described in which diffusion of a hydrogen atom takes place effectively in one dimension. The exact differential diffusion equations can be set up and solved, taking into account the possibility of gas-phase removal of the hydrogen atom by a reaction such as H + C 2 H 4 = C 2 H 5 . The collision efficiency of such a reaction has been related to the fraction of hydrogen atoms which reach the oxide layer under certain well-defined conditions. The calculated distribution curves of hydrogen atom concentration throughout the reaction vessel are also given under various conditions.

The State of Hydrogen Desorbing from Intermediates Formed by Ammonia Interaction with Tungsten Surfaces

1974 ◽  
Vol 52 (7) ◽  
pp. 1147-1154 ◽  
Author(s):  
Y. K. Peng ◽  
P. T. Dawson
Keyword(s):  
Hydrogen Atom ◽  
Atomic Hydrogen ◽  
Surface Concentration ◽  
Hydrogen Desorption ◽  
Pure Hydrogen ◽  
Adsorbed Hydrogen ◽  
Tungsten Filament ◽  
Hydrogen Atoms ◽  
Ionization Source ◽  
Hydrogen Desorbing

Ammonia interaction with a tungsten surface can generate dense adlayers containing nitrogen and hydrogen, i.e. an η-species of surface stoichiometry Ws2N3H. In thermal desorption mass spectrometry experiments, hydrogen desorbing from the η-species interacts with the glass wall in a manner similar to that previously observed for atomic hydrogen. This paper describes two mass spectrometric techniques designed to confirm this conclusion directly. The first method uses a line-of-sight geometry between the tungsten filament and the ionization source of the mass spectrometer and the results indicate that, at least, part of the hydrogen desorbing from the η-species does so atomically. In the second method a multiple wall collision geometry is used but prior saturation of the wall with D atoms will result in an HD+ ion current for desorbing H atoms. The results suggest that 26% of the hydrogen desorbs atomically. Hydrogen atom desorption from the η-species occurs at tungsten filament temperatures below those required for hydrogen atom evaporation from a pure hydrogen adlayer. It is proposed that a reduced binding energy for adsorbed hydrogen atoms and a reduced mobility of these adatoms arises from the presence of a large surface concentration of nitrogen. This will result in the rates of atomic hydrogen desorption and bimolecular recombination becoming comparable at temperatures lower than is the case for pure hydrogen interaction with tungsten. The implications of these results for the ammonia synthesis reaction are discussed.

scholarly journals The kinetics of the interaction of atomic hydrogen with olefines I. Apparatus and use of para-hydrogen techniques

1949 ◽  
Vol 196 (1047) ◽  
pp. 445-465 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Saturated Hydrocarbon ◽  
Oxide Surface ◽  
Para Hydrogen ◽  
Hydrocarbon Molecule ◽  
Hydrogen Atoms ◽  
Collision Efficiency ◽  
Wide Range ◽  
New Type ◽  
Kinetics Of

It is shown in this paper that the normal techniques and methods of approach to an investigation of radical reactions are not applicable in dealing with reactions involving the addition of a hydrogen atom to an olefine, since this type of reaction is so fast that even the exchange conversion of para-hydrogen by hydrogen atoms is inhibited by very small amounts of olefines. A new type of reaction has been utilized to provide a means of competing with the olefine for a hydrogen atom, namely, the removal of a hydrogen atom on a layer of molybdenum oxide or tungsten oxide. In order to adapt the system to the measurement of reactions over a wide range of collision efficiency, a special reaction vessel is described in which the path length offered to a hydrogen atom before removal on the oxide layer can be varied. A colorimetric technique has been devised for measuring the rate of addition of hydrogen atoms to the oxide surface. This technique is shown to be very sensitive, and the addition of a very small amount of hydrogen atoms can be detected. The para-hydrogen conversion technique has been applied to illustrate how the collision efficiency of a hydrogen atom with a saturated hydrocarbon molecule can be obtained. The reaction H + R H = H 2 + R has approximately the same collision efficiency as the reaction H + p -H 2 = n -H 2 + H, and hence in the presence of a saturated hydrocarbon there is no inhibition of the para-conversion, only retardation. A further application of the para-conversion has been to demonstrate the efficiency of the removal of a hydrogen atom on the oxides of molybdenum and tungsten.

Formation of surface layer of hydrogen in pure aluminum

2019 ◽  
Vol 484 (1) ◽  
pp. 56-60
Author(s):  
D. A. Indejtsev ◽  
E. V. Osipova
Keyword(s):  
Surface Layer ◽  
Hydrogen Atom ◽  
Ab Initio ◽  
Pure Aluminum ◽  
Hydrogen Atoms ◽  
Energy Characteristics ◽  
Aluminum Crystal

Hydrogen atom behavior in pure aluminum is described by ab initio modelling. All main energy characteristics of the system consisting of hydrogen atoms in a periodic aluminum crystal are found.

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