The combustion of hydrogen sulphide studied by flash photolysis and kinetic spectroscopy

1957 ◽  
Vol 240 (1222) ◽  
pp. 293-303 ◽  
Keyword(s):  
Low Temperature ◽  
Absorption Spectra ◽  
Hydrogen Sulphide ◽  
Sulphur Dioxide ◽  
Flash Photolysis ◽  
Light Emission ◽  
Inert Gas ◽  
Large Excess ◽  
Kinetic Spectroscopy ◽  
Combustion Of Hydrogen

The combustion of hydrogen sulphide has been investigated by the method of kinetic spectroscopy and flash photolysis. If no large excess of inert gas is present the reaction produces sulphur dioxide. The reaction has been shown to take place in steps in which the radicals SH and OH participate. Simultaneously with the appearance of the sulphur dioxide; a light emission has been observed which is attributed to the process: SO + O→SO2 + hv . In the presence of a large excess of inert gas the reaction results in S 2 O 2 . It has been shown that the formation of S 2 O 2 is favoured by a low temperature. Flash photolysis of hydrogen sulphide, sulphur dioxide and S 2 O 2 has also been investigated. In the last two cases the absorption spectra disappear temporarily. Inert gas prevents the disappearance of the SO 2 , but not that of S 2 O 2 . From an analysis of our results a mechanism for the combustion of hydrogen sulphide is derived and discussed.

Studies of the explosive combustion of hydrocarbons by kinetic spectroscopy I. Free radical absorption spectra in acetylene combustion

1953 ◽  
Vol 216 (1125) ◽  
pp. 165-183 ◽  
Keyword(s):  
Absorption Spectra ◽  
Total Pressure ◽  
Flash Photolysis ◽  
Initial Period ◽  
Kinetic Spectroscopy ◽  
Radical Concentration ◽  
Stage 4 ◽  
Explosive Reaction ◽  
Stage 1 ◽  
Flash Spectroscopy

The explosive oxidation of acetylene, initiated homogeneously by the flash photolysis of a small quantity of nitrogen dioxide, has been investigated by flash spectroscopy. The absorption spectra of OH, CH, C 2 (singlet and triplet), C 3 , CN and NH, a number of which have not previously been observed, are described, and the relative concentrations, at all times throughout the explosion, are given. Four stages have been distinguished in the explosive reaction: 1. An initial period during which only OH appears. 2. A rapid chain branching involving all the diatomic radicals. 3. Further reaction, occurring only when oxygen is present in excess of equimolecular proportions, during which the OH concentration rises exponentially and the other radicals are totally consumed. 4. A relatively slow exponential decay of the excess radical concentration remaining after completion of stages 2 and 3. The duration of stage 1 is 0 to 3 ms. In an equimolecular mixture at 20 mm total pressure, containing 1.5 mm NO 2 , the durations of both stage 2 and stage 3 are approximately 10 -4 s and the half-life of OH in stage 4 is 0.28 ms. A preliminary interpretation of these changes and of the radical reactions is given.

Fluorescence and vibrational relaxation of nitric oxide studied by kinetic spectroscopy

1961 ◽  
Vol 260 (1303) ◽  
pp. 459-474 ◽  
Keyword(s):  
Nitric Oxide ◽  
Vibrational Relaxation ◽  
High Pressures ◽  
Flash Photolysis ◽  
Electronic States ◽  
Analytic Form ◽  
Gas Mixtures ◽  
Inert Gas ◽  
Flash Duration ◽  
Kinetic Spectroscopy

The first excited vibrational level of the ground electronic states of nitric oxide was popu­lated above its equilibrium value by flash photolysis of nitric oxide + inert gas mixtures, under isothermal conditions. Electronic excitation NO 2 II ( v = 0) + hv → NO 2 Ʃ ( v = 0, 1, 2) was followed either by fluorescence NO 2 Ʃ ( v = 0, 1, 2) → NO 2 II ( v = 0, 1, 2...) + hv , or by quenching NO 2 Ʃ ( v = 0, 1, 2) + M → NO 2 II( v = 0, 1, 2...) + M , causing a non-equilibrium population of the vibrational levels of the ground electronic states. Subsequently, the reactions NO 2 II ( v = 1) + M → NO 2 II ( v = 0) + M and NO 2 II ( v = 1) + NO 2 II ( v = 0) → 2NO 2 II ( v = 1) caused a decay of the vibrationally excited molecules with time; this was followed in absorption by kinetic spectroscopy. Because of the rapidity of the last reaction, bands of NO2 II with v >1 were usually observed only in the fluorescence spectrum. In mixtures of 1 to 5 mm of NO with a large excess of nitrogen or krypton, the con­centration of NO2 II ( v = 1) produced by the flash was of the order of 10-1 mm pressure, i. e. about the same concentration which is present in one atmosphere pressure of NO at room temperature. The absolute concentration of NO2 II ( v = 1) was measured accurately by plate photometry, high pressures of NO being used for calibration. The recorded probabilities of vibrational relaxation, P1-0, for NO2 II ( v = 1), and radii for electronic quenching, σ e , by NO, N 2 , CO, H 2 O and CO 2 , are P 1-0 σ e (Å) NO 3.55 x 10 -4 14 N 2 4 x 10 -7 ≤ 2x 10 -2 CO 2.5 x 10 -5 0.6 H 2 O 7 x 10 -3 30 CO 2 1.7 x 10 -4 5 With the use of an analytic form for the flash duration, the entire rise and fall of the concentration of excited species was quantitatively interpreted. A very small fraction of the NO was decomposed by the flash, due either to absorption of radiation below 1900 Å or by reaction of metastable NO molecules with each other or with ground state molecules. Abnormal effects were observed in NO+ H 2 +inert gas mixtures and chemical reaction occurred.

The flash photolysis of chlorine monoxide

1957 ◽  
Vol 243 (1232) ◽  
pp. 24-32 ◽  
Keyword(s):  
Chlorine Dioxide ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Reaction Scheme ◽  
Inert Gas ◽  
Short Chain ◽  
Large Excess ◽  
Straight Chain ◽  
Chain Reaction ◽  
Chlorine Monoxide

The flash photolysis of chlorine monoxide in a large excess of inert gas yields chlorine and oxygen, the normal products of photolysis, accompanied by measurable quantities of the ClO radical as an intermediate. The normal and chlorine-sensitized decompositions of chlorine monoxide are studied and a reaction scheme is proposed for the system which has the character of a short-chain reaction with CIO and CI acting as chain carriers. By a study of the decay of the CIO radical and the formation of chlorine dioxide, rate constants are derived for the CIO decay, the production of chlorine dioxide and the straight-chain decomposition of chlorine monoxide by the CIO radical.

New Observations on the Low Temperature Reaction between Hydrogen Sulphide and Sulphur Dioxide : A Novel Method for Analysing Milligram Quantities of Hydrogen Sulphide in the Presence of Carbon Dioxide

1959 ◽  
Vol 12 (3) ◽  
pp. 424 ◽  
Author(s):  
IK Gregor ◽  
RL Martin
Keyword(s):  
Carbon Dioxide ◽  
Low Temperature ◽  
Hydrogen Sulphide ◽  
Sulphur Dioxide ◽  
High Vacuum ◽  
Temperature Reaction ◽  
Liquid Sulphur ◽  
Vacuum Method ◽  
Novel Method ◽  
Vacuum Fractionation

When an anhydrous mixture of liquid hydrogen sulphide and liquid sulphur dioxide contained in a sealed tube at -78 �C is gently warmed, the liquid remains clear until the temperature reaches c. -40 �C, when sulphur is slowly deposited. Careful measurements reveal that the two compounds always react in the mole ratio, H2S : SO2 = 3 : 2, which contrasts with the stoichiometric equation 2H2S + SO2 =2H2O + 3S, widely quoted for their reaction in the moist gaseous phase or in aqueous solution. This low temperature reaction forms the basis of a novel high vacuum method for estimating milligram quantities of hydrogen sulphide when in the presence of gases, such as carbon dioxide, whose volatilities are sufficiently similar to preclude the use of normal low-temperature vacuum fractionation methods.

Kinetic spectroscopy in the far ultra-violet: the flash photolysis of ethyl compounds

1958 ◽  
Vol 243 (1235) ◽  
pp. 555-560 ◽  
Keyword(s):  
Absorption Spectra ◽  
Lithium Fluoride ◽  
Flash Photolysis ◽  
Ultra Violet ◽  
Transient Species ◽  
Methyl Radical ◽  
Kinetic Spectroscopy ◽  
Ethyl Radicals

An apparatus is described for the recording of the far u. v. absorption spectra of transient species produced by flash photolysis. Using lithium fluoride windows, observations can be made down to 1250 Å. The flash photolysis of mercury diethyl and lead tetraethyl yield appreciable amounts of the methyl radical, and it is thought that these are formed by reaction between ethyl radicals, one of which is excited.

Absorption Spectra of Substituted 2-Phenylindan-1,3-Dion-2-YL Radicals in Solution

1983 ◽  
Vol 38 (12) ◽  
pp. 1337-1341
Author(s):  
J. Zechner ◽  
N. Getoff ◽  
I. Timtcheva ◽  
F. Fratev ◽  
St. Minchef
Keyword(s):  
Free Energy ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Bathochromic Shift ◽  
Substitution Effects ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Abstract Flash photolysis of a series of 2-phenylindandione-1,3 derivatives substituted in the 4′ position results in both the formation of stable benzylidenephthalides and of phenylindan-1,3-dion-2-yl radicals. The u. v. absorption maxima of these radicals are dependent on the solvent and show a bathochromic shift upon substitution. These substitution effects were correlated by means of a linear free energy relationship. Attempts were made to draw conclusions concerning the changes in the gap of the states involved and their curvature due to substitution.

Sign in / Sign up

Export Citation Format

Share Document