The Photolysis of Benzoic Acid in the Vapor Phase

1972 ◽  
Vol 50 (13) ◽  
pp. 2017-2021 ◽  
Author(s):  
Francis Chau ◽  
Cyril Gibbons ◽  
Donald Barton
Keyword(s):  
Carbon Dioxide ◽  
Benzoic Acid ◽  
Vapor Phase ◽  
Ground State ◽  
Flow System ◽  
Incident Light ◽  
Chain Mechanism ◽  
Vibrationally Excited ◽  
Radical Chain ◽  
A Minor

The photolysis of benzoic acid in the vapor phase has been investigated in a flow system at temperatures ranging from 110–305 °C, pressures from 0.06–1.73 Torr, and at various incident light intensities. Carbon dioxide and benzene are the main products and carbon monoxide is a minor product. The rate of formation of carbon dioxide is proportional to the first power of the light intensity and is independent of benzoic acid concentration at pressures from 0.29–1.73 Torr. The activation energy for carbon dioxide formation is approximately 3 kcal per mol. A radical chain mechanism has been suggested, in which initiation results from decomposition of vibrationally excited ground state benzoic acid molecules, and termination occurs at the wall. A molecular mechanism is a possibility if the rate of formation of vibrationally excited ground state is a function of temperature.

scholarly journals THE REACTION OF OXYGEN ATOMS WITH CARBON TETRACHLORIDE

1962 ◽  
Vol 40 (3) ◽  
pp. 486-494 ◽  
Author(s):  
A. Y-M. Ung ◽  
H. I. Schiff
Keyword(s):  
Carbon Dioxide ◽  
Carbon Tetrachloride ◽  
Carbon Atom ◽  
Flow System ◽  
Primary Process ◽  
Chain Mechanism ◽  
Homogeneous Reaction ◽  
Secondary Reactions ◽  
Primary Reactions ◽  
A Chain

The homogeneous reaction between O atoms and CCl4 was studied in a flow system under conditions of complete consumption of atoms, in the presence and in the absence of molecular oxygen. The only products of the reaction are Cl2, CO, CO2, and COCl2. No compounds containing more than one carbon atom were detected. The dependence of the products on CCl4 concentration suggests that the primary reactions are[Formula: see text]which are too slow to consume all the atoms. Carbon dioxide is produced by secondary reactions which are fast enough to consume all the atoms, the most important of which is[Formula: see text]However, the dependence of the ratio (CO2 + COCl2/CO on CCl4 concentration in the presence of O2 indicates other reactions also produce CO2. The rapid disappearance of O atoms in the systems containing O2 suggests a chain mechanism in which Cl2 is mainly converted to the atomic form. Carbon dioxide can then be produced by the sequence[Formula: see text]The rate constant for the primary process was found to be independent of O, O2, and CCl4 concentration and could be represented by the equation[Formula: see text]

CN Emission in Active Nitrogen. II. The Role of Energy Transfer and Atom Transfer Reactions in CN(X2Σ+) Excitation

1972 ◽  
Vol 50 (16) ◽  
pp. 2527-2536 ◽  
Author(s):  
G. M. Provencher ◽  
D. J. McKenney
Keyword(s):  
Energy Transfer ◽  
Ground State ◽  
Absolute Intensity ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Band Emission ◽  
Electronically Excited ◽  
Order Of Magnitude ◽  
Three Body ◽  
A Minor

A simplified mechanism is presented for excitation of ground state CN(X2Σ+) formed from carbonaceous impurity in flowing N2 subjected to a microwave discharge. Analysis of absolute intensity data from spectrometer recordings of CN(B2Σ+ → X2Σ+) violet band emission enabled order of magnitude estimates of rate constants for CN(X2Σ+) excitation by energy transfer from vibrationally excited ground state nitrogen, [Formula: see text][Formula: see text]and formation of electronically excited NCN* in a three body reaction[Formula: see text]Energy transfer from [Formula: see text] is shown to be a minor source of excitation of CN to radiative levels. N2(A) is a source of vibrationally excited ground state nitrogen, [Formula: see text] which in turn excites CN. Vibrational population profiles under all conditions in this work are shown to be primarily a function of [Formula: see text] Evidence for the participation of the A2Π state of CN is shown in the population maxima at ν = 4 and 10 of the B2Σ+ state.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

Radical Chain Reduction via Carbon Dioxide Radical Anion (CO2•–)

2021 ◽  
Author(s):  
Cecilia M. Hendy ◽  
Gavin C. Smith ◽  
Zihao Xu ◽  
Tianquan Lian ◽  
Nathan T. Jui
Keyword(s):  
Carbon Dioxide ◽  
Radical Anion ◽  
Radical Chain

scholarly journals The Microwave Spectrum of 3,4-Dihydro-1,2-Pyran

1985 ◽  
Vol 40 (9) ◽  
pp. 913-919
Author(s):  
Juan Carlos López ◽  
José L. Alonso
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Principal Axis ◽  
Microwave Spectrum ◽  
Average Intensity ◽  
Ring Conformation ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Displacement Measurements

Abstract The rotational transitions of 3,4-dihydro-1,2-pyran in the ground state and six vibrationally excited states have been assigned. The rotational constants for the ground state (A = 5198.1847(24), B = 4747.8716(24) and C = 2710.9161(24) have been derived by fitting μa, μb and μc-type transitions. The dipole moment was determined from Stark displacement measurements to be 1.400(8) D with its principal axis components |μa| =1.240(2), |μb| = 0.588(10) and |μc| = 0.278(8) D. A model calculation to reproduce the ground state rotational constants indicates that the data are consistent with a twisted ring conformation. The average intensity ratio gives vibrational separations between the ground and excited states of the ring-bending and ring-twisting modes of ~ 178 and ~ 277 cm-1 respectively.

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.

A New Multi-Functional Cu(II)-Organic Framework as a Platform for Selective Carbon Dioxide Chemical Fixation and Separation of Organic Dyes

CrystEngComm ◽  
2021 ◽  
Author(s):  
Yang-Tian Yan ◽  
Chen-Yang Wang ◽  
Li-Na Zheng ◽  
Yun-Long Wu ◽  
Jiao Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Benzoic Acid ◽  
Organic Dyes ◽  
Metal Organic Framework ◽  
Chemical Fixation ◽  
Acid Ligand ◽  
Metal Organic ◽  
Organic Framework

A new multi-functional metal-organic framework, {[Cu2(HL)(H2O)2]·NMP·2H2O}n (1), was assembled employing a asymmetrical V-shaped rigid multicarboxylic acid ligand H5L (H5L= 2,4-di(2′,5′-dicarboxylphenyl)benzoic acid) with Cu(II) ions. 1 possesses a 3D pore formed...

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