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.

Vibrationally excited nitric oxide produced in the flash photolysis of nitrosyl halides

1962 ◽  
Vol 268 (1334) ◽  
pp. 291-303 ◽  
Keyword(s):  
Nitric Oxide ◽  
Energy Transfer ◽  
Ground State ◽  
Vibrational Relaxation ◽  
Direct Evidence ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Electronic States ◽  
Vibrationally Excited ◽  
Direct Production

The flash photolysis of nitrosyl chloride and nitrosyl bromide has been studied under isothermal conditions. Vibrationally excited nitric oxide molecules were produced and all levels from v " = 0 to v " = 11 were observed in absorption from the ground electronic states in the β, γ, δ and Є systems. Some of these bands have not previously been reported. The mechanism of the production is either directly NO R + hv → NO ( X 2 II , v ≤ 11) + R ( 2 P ), or by the sequence which includes the reactions NO R + hv → NO( 4 II ) + R , NO. 4 II + M → NO ( X 2 II , v > 0) + M In the latter case, the 4 II state of NO lies not more than 3·5 eV above the ground state. Other possible mechanisms and models accounting for the direct production of vibrationally excited NO in its ground electronic states are discussed. By flashing chlorine in the presence of NOCl it was shown that the reaction Cl + NOCl → Cl 2 + NO ( v > 0) does not occur, thus providing direct evidence that in reactions of the type A + BCD → AB + CD only the AB molecule containing the newly formed bond can be vibrationally excited. Vibrational relaxation is very rapid and probably occurs by step-wise degradation involving resonance vibrational energy transfer. NOCl and NOBr are very efficient and with NO itself the reaction NO ( v = n ) + NO ( v = 0) → NO ( v = n -1) + NO ( v = 1) can be followed.

The photolysis and pyrolysis of nitromethane and methyl nitrite

1967 ◽  
Vol 299 (1458) ◽  
pp. 317-336 ◽  
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Dioxide ◽  
Elevated Temperatures ◽  
Flash Photolysis ◽  
Stable Form ◽  
Methyl Radicals ◽  
Elimination Reaction ◽  
Kinetic Spectroscopy ◽  
Methyl Nitrite ◽  
A Minor

The photolysis and pyrolysis of nitromethane and methyl nitrite have been studied using the techniques of flash photolysis and kinetic spectroscopy. The results show that photolysis of nitromethane yields methyl radicals and nitrogen dioxide, and that these fragments undergo recombination and disproportionation reactions to form methyl nitrite, methoxyl, and nitric oxide. In the presence of added nitric oxide, the methyl radicals react principally with nitric oxide to form nitrosomethane, which subsequently dimerizes and also reacts further with nitric oxide to yield nitrogen dioxide. The evidence also suggests that nitrosomethane is removed by a relatively efficient reaction with nitrogen dioxide at elevated temperatures to produce nitromethane and nitric oxide. In the case of methyl nitrite, light absorption results not only in photolysis, but also in the formation of an isomer of the nitrite which then reverts slowly to the stable form. The nature of this isomer is not known, but possibilities are suggested and discussed. It is concluded that the decomposition (photolytic or pyrolytic) of methyl nitrite occurs by the rupture of the O—N bond, and that the methoxyl radicals formed disproportionate to yield methanol and form aldehyde. Nitroxyl is also formed but only as a minor product, and the marked increase in intensity of its spectrum in the presence of added nitric oxide shows that it is not formed by a molecular elimination reaction, but probably by CH 3 O + NO → CH 2 O + HNO.

Vibrational relaxation of nitric oxide and carbon monoxide, studied by kinetic spectroscopy

1962 ◽  
Vol 269 (1337) ◽  
pp. 180-187 ◽  
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Vibrational Relaxation ◽  
Vibrationally Excited ◽  
Kinetic Spectroscopy ◽  
Excited Molecules

Vibrationally excited carbon monoxide was produced by flashing mixtures of nitric oxide, carbon monoxide and nitrogen. The rate of formation and decay of the vibrationally excited molecules was interpreted by means of the processes: NO ( X 2 I I , υ = 0 ) + h v → NO ( A 2 ∑ + , υ = 0 , 1 , 2 ) , NO ( A 2 ∑ + , υ = 0 , 1 , 2 ) + M →→ NO ( X 2 I I , υ = 1 ) + M , NO ( A 2 ∑ + , υ = 0 , 1 , 2 ) →→ NO ( X 2 I I ) , υ = 1 ) + h v , NO ( X 2 I I , υ = 1 ) + CO X 1 ∑ + ( υ = 0 ) → ← NO ( X 2 I I , υ = 0 ) + CO ( X 1 ∑ + , υ = 1 ) , CO ( X 1 ∑ + , υ = 1 ) + N 2 X 1 ∑ V + ( υ = 0 ) → ← CO ( X 1 ∑ + , υ = 0 ) + N 2 ( X 1 ∑ V + , υ = 1 ) , NO ( X 2 I I , υ = 1 ) + NO X 2 I I ( υ = 0 ) → 2 NO ( X 2 I I , υ = 0 ) .

THE REACTION OF ISOPROPANOL VAPOR WITH Hg 6(3P1) ATOMS: PART II: REACTION IN THE PRESENCE OF NITRIC OXIDE

1963 ◽  
Vol 41 (3) ◽  
pp. 763-769 ◽  
Author(s):  
Arthur R. Knight ◽  
Harry E. Gunning
Keyword(s):  
Nitric Oxide ◽  
Room Temperature ◽  
High Pressures ◽  
New Products ◽  
Reaction Vessel ◽  
Inert Gas ◽  
Primary Process ◽  
Static System ◽  
Carbon Tetrafluoride ◽  
Dark Reaction

The reaction of isopropanol vapor with Hg 6(3P1) atoms in the presence of nitric oxide has been investigated in a static system at room temperature as a function of exposure time. In addition to the major products hydrogen, pinacol, and acetone found in the pure substrate reaction, the new products isopropyl nitrite, nitrous oxide, and nitrogen were observed. The effect on the reaction of the inert gas carbon tetrafluoride was also studied.Evidence is adduced for the production of excited isopropoxy radicals in the primary process, and the rise in the nitrite and acetone yields, observed upon increasing the added inert gas pressure, is ascribed to quenching of these excited species.The nitrite produced in the decomposition of Me2CDOH was found to be ca. 98% Me2CDONO, dictating its formation from the isopropoxy radical and not from Me2COH.A nitrite-producing dark reaction was observed when high pressures of CF4 were added and the reaction could be prevented only by measures designed to exclude trace quantities of NO2 from the reaction vessel.

The explosive oxidation of ammonia and hydrazine studied by kinetic spectroscopy

1963 ◽  
Vol 273 (1353) ◽  
pp. 145-164 ◽  
Keyword(s):  
Nitric Oxide ◽  
Ammonia Oxidation ◽  
Flash Photolysis ◽  
General Scheme ◽  
Parent Molecule ◽  
Kinetic Spectroscopy ◽  
System A ◽  
Major Reaction ◽  
Hydrazyl Radical ◽  
Oxidation Of Ammonia

The explosive oxidation of ammonia and hydrazine are studied by the method of flash photolysis and kinetic spectroscopy. The propagating reactions describing the oxidation of ammonia are concluded to be NH 2 + O 2 = HNO + OH and OH + NH 3 = NH 2 + H 2 O, nitric oxide being the main product and resulting from the breakdown of HNO. The oxidation of hydrazine is described by two mechanisms for the two separate overall reactions. It is concluded that the minor reaction yielding nitric oxide as the product results from the splitting of N 2 H 3 into NH and NH 2 , the propagating reactions being NH + O 2 = NO + OH and OH + N 2 H 4 = N 2 H 3 + H 2 O. The major reaction giving rise to nitrogen as the product is described in terms of a mechanism which does not involve the fission of the N—N bond. A successive dehydrogenative mechanism is considered though a scheme analogous to that in the ammonia oxidation involving nitrosamine, NH 2 NO, via the reaction N 2 H 3 + O 2 = NH 2 NO + OH is favoured in the light of the evidence. A general scheme for the oxidation of non-metal hydrides is considered. Preliminary experiments were carried out on the photolyses of ammonia and hydrazine. The thermal nature of the decomposition of ammonia has been illustrated, a strong NH spectrum being observed when the conditions for a temperature rise were chosen. Hydrazine has been detected as a product in this system. A mechanism in agreement with that postulated by Ramsay is reported for the photolysis of hydrazine, the first step being the splitting of the N—N bond followed by abstraction reactions on the parent molecule, fission of the hydrazyl radical occurring to a small extent only when explosion takes place. These preliminary studies served as a basis for the investigation of the combustion reactions.

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.

Singlet Methylene Removal Rate Constants from the (0,1,0) Vibrational Level: Enhancement via Complex-Mediated Vibrational Relaxation

2001 ◽  
Vol 215 (6) ◽  
Author(s):  
M.A. Buntine ◽  
G.J. Gutsche ◽  
W.S. Staker ◽  
M.W. Heaven ◽  
K.D. King ◽  
...  
Keyword(s):  
Vibrational Level ◽  
Rate Constants ◽  
Vibrational Relaxation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Removal Rate ◽  
Laser Flash ◽  
Laser Absorption ◽  
Photolysis Laser ◽  
Singlet Methylene

The technique of laser flash photolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene,

Oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures

1977 ◽  
Vol 11 (5) ◽  
pp. 225-239 ◽  
Author(s):  
John Stringer
Keyword(s):  
Gas Mixtures ◽  
Inert Gas

A redetermination of the thermal diffusion factor for some inert gas mixtures. I

1971 ◽  
Vol 4 (11) ◽  
pp. 1548-1563 ◽  
Author(s):  
K E Grew ◽  
W A Wakeham
Keyword(s):  
Thermal Diffusion ◽  
Gas Mixtures ◽  
Inert Gas ◽  
Diffusion Factor ◽  
Thermal Diffusion Factor

Vibrational relaxation of BF3 in the range 182–473 K and in rare-gas mixtures at 295 K

1977 ◽  
Vol 52 (2) ◽  
pp. 219-223 ◽  
Author(s):  
R. Kadibelban ◽  
W. Janiesch ◽  
R. Ahrens-Botzong ◽  
P. Hess
Keyword(s):  
Vibrational Relaxation ◽  
Gas Mixtures ◽  
Rare Gas
Sign in / Sign up

Export Citation Format

Share Document