Laser induced fluorescence of CFCl and CCl2 in the gas phase

doi:10.1016/0009-2614(77)80383-7

Chemical Physics Letters

Volume 51, Issue 2, 15 October 1977, Pages 197-200

https://doi.org/10.1016/0009-2614(77)80383-7 Get rights and content

Abstract

The fluorescence of CFCl and CCl₂ excited by a tunable dye laser has been observed in the gas phase. The radiative lifetimes are 644 ± 18 and 3810 ± 300 ns respectively consistent with matrix results. The quenching rate of CCl₂ is greater than for CFCl and varies with the wavelength of excitation.

References (20)

D.E. Tevault et al.
J. Mol. Spectry.
(1975)
D.E. Tevault et al.
J. Mol. Spectry.
(1975)
V.E. Bondybey
J. Mol. Spectry.
(1976)
V.E. Bondybey
J. Mol. Spectry.
(1977)
D.E. Milligan et al.
J. Mol. Spectry.
(1976)
D.E. Milligan et al.
J. Chem. Phys.
(1967)
C.E. Smith et al.
J. Chem. Phys.
(1971)
J.S. Shirk
J. Chem. Phys.
(1971)
V.E. Bondybey and J.H. English, J. Mol. Spectry, to be...
P. Venkateswarlu
Phys. Rev.
(1950)

There are more references available in the full text version of this article.

Cited by (72)

Quantum chemical and kinetic study of the CCl<inf>2</inf> + HCl → CHCl<inf>3</inf> insertion reaction
2020, Computational and Theoretical Chemistry
Citation Excerpt :
The ground state singlet CCl2 biradical is formed in the pyrolysis, combustion and photolysis of chlorinated hydrocarbons and is the main product in the thermal decomposition of CHCl3 and CCl2CO [4]. Hine et al. have also studied the formation of CCl2 in the basic hydrolysis of CHCl3 [5] and Huie et al. have obtained CCl2 radicals through the O(3P) + CF2CCl2 → F2CO + CCl2 [6] reaction. At present, the kinetics of this radical is an active area of research since it is a highly reactive intermediate.
The CCl₂ + HCl → CHCl₃ (1) insertion reaction has been investigated by ab initio molecular orbital and kinetic calculations. The geometries of reactants, products and transition state were optimized with a large number of density functional theory (DFT) formulations combined with the 6-311++G(3df,3pd) basis set. The reaction barriers calculated with G4(MP2)//DFT and G4//DFT theories of 1.16 ± 0.27 and 0.61 ± 0.26 kcal mol⁻¹ are consistent with the barrier height of ΔE₀^# = 1.54 ± 0.30 kcal mol⁻¹ estimated from the room temperature experimental rate constant. Calculated enthalpies of reaction of −53.97 ± 0.09 (G4(MP2)//DFT), −55.27 ± 0.09 (G4//DFT) and −56.52 ± 3.90 kcal mol⁻¹ (DFT) agree well with experimental values. The obtained rate constants over the 300–2000 K temperature range at the high and low pressure limit can be expressed as k_1,∞(G4(MP2)//DFT) = (4.8 ± 1.8) × 10⁻¹⁴ (T/300 K)^2.12±0.19 and k_1,∞(G4//DFT) = (9.8 ± 3.4) × 10⁻¹⁴ (T/300 K)^1.77±0.16 in cm³ molecule⁻¹ s⁻¹, and k_1,0 = [HCl] 3.40 × 10⁻²⁷ (T/300 K)^−6.57 exp(−2218 K/T) cm³ molecule⁻¹ s⁻¹. Falloff curves for the intermediate pressure range obtained for the reactions (1, −1) with these rate constants and a derived central broadening factor of F_cent = 0.16 + 0.84 exp(−T/331 K) + exp(−7860 K/T) were compared with reported experimental rate data.
Ab initio study and spectral simulation of the X̃1A <inf>1</inf> → X̃2B<inf>1</inf> photodetachment processe of dichlorocarbene anion
2013, Chemical Physics Letters
Combining ab initio molecular orbital calculations with Franck–Condon analysis to simulate vibrationally resolved photoelectron spectra have been carried out on the ${CCl}_{2} ({\tilde{X}}^{1} A_{1}) \leftarrow {CCl}_{2}^{-} ({\tilde{X}}^{2} B_{1})$ detachment process. By using CCSD/6-311+G(2d, p) values, the theoretical spectra obtained are in agreement with the observed one, and, the equilibrium geometry parameters, 1.890 ± 0.002 Å and 102.9 ± 0.3° of the ${\tilde{X}}^{2} B_{1}$ state of CCl₂⁻ are acquired, by employing an iterative Franck–Condon (IF–C) analysis procedure. In addition, on different levels of theory, our best calculated electron affinity (EA) is in fair agreement with the experimental value.
Reaction kinetic studies of CCl<inf>2</inf> (X̃(0,0,0)) with C <inf>2</inf>H<inf>2</inf> and H<inf>2</inf>O molecules
2004, Chemical Physics
Absolute reaction rate constants for the ground state dichlorocarbene CCl₂ with C₂H₂ and H₂O have been measured (T=293 K). The CCl₂ radicals were produced by laser photolysis of CCl₄ molecules at 213 nm and then electronically excited to the CCl₂ ( $A ̃$ ) state at 541.0 nm with Nd:YAG laser pumped dye laser. The technique of laser-induced fluorescence was employed to measure the relative concentrations at different reaction time and, then, obtain their rate constants. They are (3.3 ± 0.5) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹ for the reaction of CCl₂ + C₂H₂ and (4.8 ± 2.0) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ for the reaction of CCl₂ + H₂O (total pressure=12 Torr, T=293 K), respectively. It is found that the rate constant for reaction CCl₂ + C₂H₂ slightly increases with the total pressure (P=10–50 Torr). But for the reaction CCl₂ + H₂O, it is independent on the total pressure. The mechanisms for these two reactions have been theoretically studied using a high-level ab initio calculation. For the reaction of CCl₂ + H₂O, it is found that there are two reaction mechanisms: insertion and addition-elimination. Three primary product channels, HCl + HClCO, HCl + trans-ClCOH and HCl + cis-ClCOH, are studied in detail. For the reaction of CCl₂ + C₂H₂, there are also two reaction mechanisms: insertion and three-cyclo-addition. The addition of C atom in CCl₂ radical to C–C triple bond in C₂H₂ molecule may be the dominant reaction channel giving a three-member-ring structure, CCl₂ CHCH radical, as the primary intermediate.
Reaction kinetic studies of CCl<inf>2</inf> (X̃(0,0,0)) with several simple molecules
2004, Chemical Physics Letters
Citation Excerpt :
In 1967 its first direct spectroscopic observation was carried out by Milligan and Jacox [1] using a matrix-isolation technique. Most of the investigations were focused on the field of spectrum, and only a few studies on reaction kinetics of CCl2 radicals have been performed [2–14]. CCl2 radicals were often produced by pyrolysis, photolysis, discharge and chemical reaction of some chlorinated hydrocarbon molecules which contain two or more chlorine atoms in same carbon atom.
Absolute reaction rate constants have been measured at room temperature for the ground state dichlorocarbene, CCl₂ with a series of simple molecules: C₂H₄, NO, N₂O, and halomethanes (T=297 K). The technique of laser-induced fluorescence was employed to obtain these rate constants. The reaction of CCl₂ + CH₂Cl₂ was theoretically studied using a high-level ab initio calculation in order to gain an insight into the mechanism for the reactions CCl₂ + halomethanes.
Kinetic studies on the collisional quenching of CCl<inf>2</inf>( Ã1B<inf>1</inf> and ã3B<inf>1</inf> ) by ketones
2001, Journal of Photochemistry and Photobiology A: Chemistry
Citation Excerpt :
In view of the extensive study of the role played by dichlorocarbene, CCl2, as an intermediate of some organic chemical reactions [1–6], direct spectroscopic observation and kinetic study of this species would be of considerable interest to both chemical physicist and chemist. Since a direct spectroscopic observation of CCl2 was carried out in 1967 by Milligan and Jacox using a matrix-isolation technique [7], CCl2 radical was produced through pyrolysis, photolysis, discharge and chemical reaction of some chlorinated hydrocarbon molecules which contain two or more chlorine atoms in the same carbon [8–25]. It is found that many industrial processes, such as plasma etching of semiconductor surface [26,27] and reprocessing of burnt nuclear fuel [28], relate to CCl2 radicals.
CCl₂ free radicals were produced by a pulsed dc discharge of CCl₄ (in Ar). The ground electronic state CCl₂ (X) radical was electronically excited to the $A ̃^{1} B_{1}$ (0 4 0) vibronic state with a Nd:YAG laser pumped dye laser at 541.52 nm. Experimental quenching data of excited CCl₂( $A ̃^{1} B_{1}$ and $a ̃^{3} B_{1}$ ) by ketone molecules were obtained by observing time-resolved total fluorescence signal of the excited CCl₂ radical, which showed a superposition of two exponential decay components under the presence of quencher. The quenching rate constants K_A of CCl₂ (A) state and K_a of CCl₂ (a) state were derived by analyzing the experimental data according to a proposed three-level-model involving $X ̃^{1} A_{1}$ , $A ̃^{1} B_{1}$ , and $a ̃^{3} B_{1}$ states. On the whole, K_A and K_a increase with increasing the number of CH bonds in ketone molecules.
The collisional quenching of CCl<inf>2</inf>(A 1B<inf>1</inf> and a 3B<inf>1</inf>) by substituted methane molecules
2001, Chemical Physics
CCl₂ free radical was produced by a pulsed dc discharge of CCl₄ (in Ar). Ground electronic state CCl₂(X) radical was electronically excited to A $^{1} B_{1}$ (0,4,0) vibronic state with Nd:YAG laser pumped dye laser at 541.52 nm. Experimental quenching data of excited CCl₂(A $^{1} B_{1}$ and a $^{3} B_{1}$ ) by CH₄, CH₃NO₂, CH₃OH, and halomethanes were obtained by observing time-resolved total fluorescence signal of the excited CCl₂ radical in a cell, which shows a superposition of two exponential decay components under the presence of a quencher. The quenching rate constants K_A of CCl₂ (A) state and K_a of CCl₂ (a) state were derived by analyzing the experimental data according to a proposed three-level model to deal with the CCl₂(X $^{1} A_{1}$ , A $^{1} B_{1}$ , a $^{3} B_{1}$ ) system. K_A and K_a increase on the whole with increasing the number of C–Cl bonds in chloromethane molecules. The formation cross sections of complexes between CCl₂(A $^{1} B_{1}$ ) radicals and CH₄, CH₃Cl, CH₃OH and CH₃NO₂ molecules were calculated by means of a collision complex model.

View all citing articles on Scopus

¹: Visiting scientist, permanent address: Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234, USA.

View full text

Article preview

Chemical Physics Letters

Abstract

References (20)

J. Mol. Spectry.

J. Mol. Spectry.

J. Mol. Spectry.

J. Mol. Spectry.

J. Mol. Spectry.

J. Chem. Phys.

J. Chem. Phys.

J. Chem. Phys.

Phys. Rev.

Cited by (72)

Quantum chemical and kinetic study of the CCl<inf>2</inf> + HCl → CHCl<inf>3</inf> insertion reaction

Ab initio study and spectral simulation of the X̃<sup>1</sup>A <inf>1</inf> → X̃<sup>2</sup>B<inf>1</inf> photodetachment processe of dichlorocarbene anion

Reaction kinetic studies of CCl<inf>2</inf> (X̃(0,0,0)) with C <inf>2</inf>H<inf>2</inf> and H<inf>2</inf>O molecules

Reaction kinetic studies of CCl<inf>2</inf> (X̃(0,0,0)) with several simple molecules

Kinetic studies on the collisional quenching of CCl<inf>2</inf>( Ã<sup>1</sup>B<inf>1</inf> and ã<sup>3</sup>B<inf>1</inf> ) by ketones

The collisional quenching of CCl<inf>2</inf>(A <sup>1</sup>B<inf>1</inf> and a <sup>3</sup>B<inf>1</inf>) by substituted methane molecules