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.

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.

Energy disequilibrium in the flash photolysis of NO 2

1973 ◽  
Vol 334 (1599) ◽  
pp. 553-568 ◽  
Keyword(s):  
Nitric Oxide ◽  
Flash Photolysis ◽  
Vibrational Energy ◽  
Dissociation Limit ◽  
Primary Process ◽  
Transfer Energy ◽  
Vibrationally Excited ◽  
Absolute Concentrations ◽  
The Absolute ◽  
Excited Oxygen

From measurements of the absolute concentrations of vibrationally excited oxygen produced in levels v" = 4 to v" = 13, it is concluded that ca . 20 % of the exothermicity of the reaction O( 3 P) + NO 2 → NO + O + 2 ( v" ≤11) (1) appears initially as vibrational energy in oxygen. Vibrationally excited nitric oxide ( v" = 1, 2) is also observed and may be produced in this reaction or in the primary process NO 2 + hv → NO ( v" ≤ 2) + O( 3 P). More highly excited oxygen ( v" ≤ 15), with energy exceeding the exothermicity of the reaction, is produced in reaction (1) when the NO 2 is first excited by radiation above the dissociation limit near 400 nm. The excited NO 2 thus produced can also transfer energy to nitric oxide. NO 2 * + NO( v" = 0) → NO 2 + NO( v" = 1).

Vibrationally excited cyanogen radicals produced in the flash photolysis of cyanogen and cyanogen halides

1963 ◽  
Vol 272 (1349) ◽  
pp. 147-163 ◽  
Keyword(s):  
Energy Transfer ◽  
Ground State ◽  
Room Temperature ◽  
Cyanogen Bromide ◽  
Flash Photolysis ◽  
Third Body ◽  
Vibrationally Excited ◽  
Vibrational Levels ◽  
Cyanogen Halides ◽  
Cyanogen Iodide

The flash photolysis of cyanogen, cyanogen bromide and cyanogen iodide has been studied under isothermal conditions. Vibrationally excited (v” ⩽ 6) cyanogen radicals were produced and observed spectroscopically in absorption, in the δ v = 0, ± 1 and — 2 sequences of the violet ( B 2 ∑ ← X 2 ∑) system. The CN radical produced in the reaction CN R + hv → CN( X 2 ∑, v = 0) + R is excited electronically, CN( X 2 ∑, v = 0)+ hv → CN ( B 2 ∑, v = 0, 1, 2, ...), and then returns to various vibrational levels of the ground state by fluorescence or collision CN( B 2 ∑, v = 0, 1, 2, ...) → CN( X 2 ∑, v = 0, 1, 2, ...) + hv , CN( B 2 ∑, v = 0, 1, 2, ...) + M → CN( X 2 ∑, v = 0, 1, 2, ...) + M . Frequent repetition of this type of excitation in the absence of relaxation would lead to a vibrational ‘tem perature’ which may be described as virtually infinite, and in any case is extremely high when relaxation is relatively slow. The alternative reactions by which vibrationally excited radicals could be produced, namely CN R + hv → CN( X 2 ∑, v ⩽ 6) + R and CN R + hv → CN( A 2 II , v > 0) + R , followed by CN( A 2 II , v > 0) → CN( X 2 ∑, v > 0), were shown to account for < 6 % of the vibrationally excited radicals observed and may be entirely inoperative. The probability of energy transfer to CNBr from the fourth vibrational level of CN, P 4-3 , was found to be approximately 1 × 10 -2 . The rate constant for the recombination of cyanogen radicals at room temperature was found to be ~ 6 x 10 11 ml. mole -1 s -1 or ~ 1.7 × 10 16 ml. 2 mole -2 s -1 with nitrogen as third body.

scholarly journals The calculation of TV, VT, VV, VV' − rate coefficients for the collisions of the main atmospheric components

1998 ◽  
Vol 16 (7) ◽  
pp. 838-846 ◽  
Author(s):  
A. S. Kirillov
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Vibrational Energy ◽  
Relaxation Times ◽  
Atmospheric Composition ◽  
Rate Coefficients ◽  
Frequency Change ◽  
Vibrational Energy Transfer ◽  
Ion Chemistry ◽  
Vibrationally Excited

Abstract. The first-order perturbation approximation is applied to calculate the rate coefficients of vibrational energy transfer in collisions involving vibrationally excited molecules in the absence of non-adiabatic transitions. The factors of molecular attraction, oscillator frequency change, anharmonicity, 3-dimensionality and quasiclassical motion have been taken into account in the approximation. The analytical expressions presented have been normalized on experimental data of VT-relaxation times in N2 and O2 to obtain the steric factors and the extent of repulsive exchange potentials in collisions N2-N2 and O2-O2. The approach was applied to calculate the rate coefficients of vibrational-vibrational energy transfer in the collisions N2-N2, O2-O2 and N2-O2. It is shown that there is good agreement between our calculations and experimental data for all cases of energy transfer considered.Key words. Ionosphere (Auroral ionosphere; ion chemistry and composition). Atmospheric composition and structure (Aciglow and aurora).

Vibrational Relaxation of Cyanide on Copper Surfaces:  Can Metal d-bands Influence Vibrational Energy Transfer?†

2002 ◽  
Vol 106 (33) ◽  
pp. 8172-8175 ◽  
Author(s):  
Christopher Matranga ◽  
Brian L. Wehrenberg ◽  
Philippe Guyot-Sionnest
Keyword(s):  
Energy Transfer ◽  
Vibrational Relaxation ◽  
Vibrational Energy ◽  
Vibrational Energy Transfer ◽  
Copper Surfaces

scholarly journals Pump- And Probe-Wavelength Dependencies of Picosecond Anti-Stokes Raman Spectrum of Trans-Stilbene in the S1 State

1999 ◽  
Vol 19 (1-4) ◽  
pp. 75-78 ◽  
Author(s):  
Takakazu Nakabayashi ◽  
Hiromi Okamoto ◽  
Mitsuo Tasumi
Keyword(s):  
Vibrational Relaxation ◽  
Vibrational Energy ◽  
Wavelength Dependence ◽  
Relaxation Dynamics ◽  
Vibrationally Excited ◽  
Time Resolved ◽  
Probe Wavelength ◽  
Trans Stilbene ◽  
Pump And Probe ◽  
Anti Stokes

Vibrational relaxation dynamics of trans-stilbene in the S1 state immediately after photoexcitation is studied by picosecond time-resolved anti-Stokes Raman spectroscopy with several pump and probe wavelengths. Pump-wavelength dependence of the anti- Stokes spectrum indicates that, when pump photons with high excess energy (≈5200cm-1) are used, the anti-Stokes Raman bands at 0 ps delay time arise from vibrationally excited transients with excess vibrational energy not thermally distributed in the molecule. Probe-wavelength dependence suggests that the vibrationally excited transients at 0 ps are mostly on the lowest excited vibrational levels, as far as the olefinic C═C stretching and the C–Ph stretching modes are concerned. The vibrational relaxation process of S1trans-stilbene is discussed on the basis of the observed results.

Energy transfer rates for vibrationally excited gas-phase azulene in the electronic ground state

1981 ◽  
Vol 78 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Gregory P. Smith ◽  
John R. Barker
Keyword(s):  
Energy Transfer ◽  
Gas Phase ◽  
Ground State ◽  
Electronic Ground State ◽  
Vibrationally Excited ◽  
Transfer Rates ◽  
Electronic Ground

Vibrational relaxation in gases

1959 ◽  
Vol 253 (1273) ◽  
pp. 277-288 ◽  
Keyword(s):  
Energy Transfer ◽  
Relaxation Process ◽  
Vibrational Relaxation ◽  
Vibrational Energy ◽  
Ultrasonic Waves ◽  
The Other ◽  
Ultrasonic Frequency ◽  
Hydrogen Atoms ◽  
Torsional Mode ◽  
Fundamental Frequencies

The velocity of ultrasonic waves has been measured in a number of gases at 25°C and for values of the ratio, ultrasonic frequency/pressure, ranging from 2 x 10 5 to 2 x 10 7 c s -1 atm -1 . Dispersion, corresponding to a single vibrational relaxation process was shown by acetylene, CD 3 Br and hexafluoro-ethane; and, to a double relaxation process, by ethane. Incipient dispersion was shown by propane, ethyl chloride, ethyl fluoride and dimethyl ether. No dispersion was shown by 1.1-difluoro-ethane, n -butane, iso -butane, neo -pentane and ammonia. Correlation of these with previous results leads to the conclusion that: ( а ) For molecules with a distribution of fundamental frequencies, such that there is only a small gap between the lowest and the remaining frequencies, vibrational activation enters via the lowest mode and spreads rapidly to the other modes, giving rise to a single relaxation process involving the whole of the vibrational energy. The chief factors determining the probability of excitation of the lowest mode are its frequency and the presence or absence of hydrogen atoms in the molecule. Molecules containing two or more hydrogen atoms suffer translational-vibrational energy transfer very much more easily than other molecules. Deuterium has almost the same effect as hydrogen. ( b ) For molecules, in which there is a large gap between the lowest and the remaining fundamental frequencies, a double relaxation process occurs. The complex energy transfer probabilities involved do not fit the same quantitative functional relation with vibrational frequency as in ( a ) above. ( c ) Torsional oscillations due to hindered internal rotation behave similarly to other fundamental modes. For molecules in which there is a large gap between the torsional frequency and the other modes (e. g. ethane) a double relaxation process occurs as in ( b ). Where there is no such gap, vibrational energy enters all modes via the torsional mode as in ( a ).

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