Gas phase EPR of vibrationally excited O2

1973 ◽  
Vol 58 (4) ◽  
pp. 1548-1552 ◽  
Author(s):  
Thomas J. Cook ◽  
Bernard R. Zegarski ◽  
William H. Breckenridge ◽  
Terry A. Miller
Keyword(s):  
Gas Phase ◽  
Vibrationally Excited

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

1983 ◽  
Vol 37 (6) ◽  
pp. 545-552 ◽  
Author(s):  
John Kishman ◽  
Eric Barish ◽  
Ralph Allen
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Band System ◽  
Electrothermal Atomization ◽  
Characteristic Radiation ◽  
Gaseous Species ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Excited Species ◽  
Intense Emission

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

Etude à basse température dans l'infrarouge proche du dimère (NO)2

1984 ◽  
Vol 62 (4) ◽  
pp. 322-329 ◽  
Author(s):  
V. Menoux ◽  
R. Le Doucen ◽  
C. Haeusler ◽  
J. C. Deroche
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Ground State ◽  
Near Infrared ◽  
Heat Of Formation ◽  
Wave Number ◽  
Vibrational Modes ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Absorption Intensity

The spectrum of the dimer (NO)2 in the gas phase has been studied in the near infrared at temperatures between 118 and 138 K. More specifically, the measure of absorption intensity of the ν4 and ν1 + ν4 bands has yielded the heat of formation of the dimer, −2.25 kcal/mol at 128 K, and revealed the influence of the low vibrational modes on this measure. The observation of the ν4 – ν6, difference band has yielded the wave number value of the ν6, fundamental band, forbidden in the infrared. The rotational constants of the vibrationally excited state were found to be larger than the ground state rotational constants, this result being very unusual.

The thermal and photochemical decomposition of maleic anhydride in the gas phase

1981 ◽  
Vol 59 (9) ◽  
pp. 1342-1346 ◽  
Author(s):  
R. A. Back ◽  
J. M. Parsons
Keyword(s):  
Maleic Anhydride ◽  
Gas Phase ◽  
Light Emission ◽  
Order Rate Constant ◽  
Static System ◽  
Collisional Quenching ◽  
Vibrationally Excited ◽  
Concerted Mechanism ◽  
Photochemical Decomposition ◽  
Weak Light

The thermal decomposition of maleic anhydride has been studied in the gas phase in a static system at temperatures from 645 to 760 K and pressures from 0.7 to 20 Torr. The first-order rate constant for the homogeneous unimolecular reaction,[Formula: see text]is described by the Arrhenius parameters log A (s−1) = 14.33 (±0.3), and E = 60.9 (± 1) kcal/mol. The reaction appears to proceed through a concerted mechanism rather than a biradical one.The photochemical decomposition, studied at wavelengths from 220 to 350 nm, yielded the same products. At 300 nm and below, the decomposition was unaffected by pressure, but at longer wavelengths collisional quenching was observed. Weak light emission was observed on excitation between 350 and 380 nm. The absorption spectrum was measured from 250 to 400 nm, and three overlapping transitions, π*←π, π*←n+, and π*←n−, can be distinguished. The mechanism of the photolysis is discussed and it is concluded that it probably proceeds through internal conversion to a vibrationally excited ground state.

Relaxation and chemical reaction of vibrationally excited molecules in the gas phase

1980 ◽  
Vol 59 ◽  
pp. 207-224 ◽  
Author(s):  
M. Kneba ◽  
R. Stender ◽  
U. Wellhausen ◽  
J. Wolfrum
Keyword(s):  
Gas Phase ◽  
Chemical Reaction ◽  
Vibrationally Excited ◽  
Excited Molecules

The Quenching of O2(1Σg+) by Aliphatic Hydrocarbons

1974 ◽  
Vol 52 (2) ◽  
pp. 240-245 ◽  
Author(s):  
J. A. Davidson ◽  
E. A. Ogryzlo
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Rate Constants ◽  
Aliphatic Hydrocarbons ◽  
Vibrationally Excited

Rate constants for the quenching of O2(1Σg+) in the gas phase have been determined for 12 aliphatic hydrocarbons. The values are discussed in terms of a mechanism in which the magnitudes of the rate constants are determined by the abilities of the quenchers to become vibrationally excited when O2(1Σg+)is relaxed to O2(1Δg).The resulting equations are tested quantitatively by relating the rate constants to the absorption spectra of the quenchers at the frequencies of the O2(1Σg+−1Δg) transition.

Photochemical studies of unimolecular processes III. Subsidiary processes in the photolysis of cycloheptatriene

1970 ◽  
Vol 316 (1524) ◽  
pp. 143-151 ◽  
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Sufficient Energy ◽  
Benzyl Radicals

In addition to toluene, the photolysis of cyclo[l. 3. 5]heptatriene (CHT) in the gas phase yields small amounts of benzene, methane, ethane, cyclopentadiene and acetylene. Most of the toluene molecules formed by the photo-isomerization of CHT have sufficient energy to dissociate to benzyl radicals and hydrogen atoms; the small fraction which do are responsible for the first three minor products. Cyclopentadiene and acetylene arise from vibrationally excited ground state CHT molecules with energies greater than 268 ± 12 kJ/mol, bicyclo[2. 2. l]heptadiene being the intermediate involved.

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