Reactions of Molecules in Defined Vibrational States VII. Absolute Rate Determination for the Reaction of D-Atoms with Vibrationally Excited H2-Molecules

1979 ◽  
Vol 83 (9) ◽  
pp. 940-942 ◽  
Author(s):  
M. Kneba ◽  
U. Wellhausen ◽  
J. Wolfrum
Keyword(s):  
Absolute Rate ◽  
Vibrational States ◽  
Vibrationally Excited

scholarly journals Model of daytime emissions of electronically-vibrationally excited products of O<sub>3</sub> and O<sub>2</sub> photolysis: application to ozone retrieval

2006 ◽  
Vol 24 (11) ◽  
pp. 2823-2839 ◽  
Author(s):  
V. A. Yankovsky ◽  
R. O. Manuilova
Keyword(s):  
Atomic Oxygen ◽  
Energy Exchange ◽  
Electronic States ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Proposed Model ◽  
Vibrational Levels ◽  
Electronically Excited ◽  
Basic Facts ◽  
Kinetics Of

Abstract. The traditional kinetics of electronically excited products of O3 and O2 photolysis is supplemented with the processes of the energy transfer between electronically-vibrationally excited levels O2(a1Δg, v) and O2(b1Σ+g, v), excited atomic oxygen O(1D), and the O2 molecules in the ground electronic state O2(X3Σg−, v). In contrast to the previous models of kinetics of O2(a1Δg) and O2 (b1Σ+g), our model takes into consideration the following basic facts: first, photolysis of O3 and O2 and the processes of energy exchange between the metastable products of photolysis involve generation of oxygen molecules on highly excited vibrational levels in all considered electronic states – b1Σ+g, a1Δg and X3Σg−; second, the absorption of solar radiation not only leads to populating the electronic states on vibrational levels with vibrational quantum number v equal to 0 – O2(b1Σ+g, v=0) (at 762 nm) and O2(a1Δg, v=0) (at 1.27 µm), but also leads to populating the excited electronic–vibrational states O2(b1Σ+g, v=1) and O2(b1Σ+g, v=2) (at 689 nm and 629 nm). The proposed model allows one to calculate not only the vertical profiles of the O2(a1Δg, v=0) and O2(b1Σ

scholarly journals Picosecond Anti-Stokes Raman Excitation Profiles as a Method for Investigating Vibrationally Excited Transients

1999 ◽  
Vol 19 (1-4) ◽  
pp. 335-341 ◽  
Author(s):  
Hiromi Okamoto ◽  
Takakazu Nakabayashi ◽  
Mitsuo Tasumi
Keyword(s):  
Vibrational Energy ◽  
Vibrational Modes ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Quantum Numbers ◽  
Trans Stilbene ◽  
Raman Process ◽  
Vibrationally Hot Molecules ◽  
Raman Excitation Profiles ◽  
Anti Stokes

A method for estimating vibrational quantum numbers of vibrationally excited transients in solution is proposed. In this method, we calculate anti-Stokes Raman excitation profiles (REPs) which are characteristic of the initial vibrational states involved in the Raman process, and compare them with observed anti-Stokes intensities. We have applied this method to vibrationally hot molecules of canthaxanthin in the So state and those of trans-stilbene in the S1 state. For canthaxanthin, it has been found that the vibrationally excited transients are for the most part on the ν=1 level of the C═C stretching mode, and that excess vibrational energy is statistically distributed among all intramolecular vibrational modes. As for S1 stilbene, vibrational transients are shown to be mostly on the ν=1 level for two vibrational modes examined, while the excess vibrational energy is probably localised on the olefinic C═C stretching mode.

THE HYDROGEN–CHLORINE SYSTEM IN THE MM PRESSURE RANGE: I. ENERGY DISTRIBUTION AMONG VIBRATIONALLY EXCITED STATES

1964 ◽  
Vol 42 (10) ◽  
pp. 2176-2192 ◽  
Author(s):  
F. D. Findlay ◽  
J. C. Polanyi
Keyword(s):  
Excited States ◽  
Rotational Temperature ◽  
Relative Rate ◽  
Infrared Emission ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Experimental Conditions ◽  
Reduced Pressure ◽  
A Chain ◽  
First Time

When atomic plus molecular hydrogen coming from a Wood's discharge tube are mixed with molecular chlorine, infrared emission is observed (1). At low reagent pressures, ~10−2 mm Hg, this emission can be related to the relative rate of the reaction H + Cl2 → HCl†ν + Cl proceeding to form HCl in vibrationally excited states ν = 1–6, of the ground electronic state. In the present work this system has been investigated for the first time at ~100 × the reagent pressure (~1 mm Hg). The reaction was shown to proceed by a chain mechanism. The translational–rotational temperature was 1300 ± 100 °K under the experimental conditions normally used. The vibrational distribution was notable for the presence of vibrators in levels ν = 7 and 8, which are respectively 4 and 10 kcal higher in energy than the exothermicity of the H + Cl2 reaction. The population in these levels appeared to be related to that in the levels with [Formula: see text]; it was proposed that vibrational–vibrational exchange among these lower levels was responsible for populating the higher ones. A simple model yielded a collision efficiency for HCl†ν=1 + HCl†ν=6 → HCl†ν=7 + HCl†ν=0, of Z1,6t = 6 × 103 collisions per transfer. Addition of HCl to the reaction mixture brought about a redistribution among vibrationally excited states indicative of a fast vibrational transfer, HClν=0 + HCl†ν=2 → 2 HCl†ν=1.At reduced pressure of HCl† the stationary-state distribution among higher vibrational states approximated closely to that observed at 10−2 mm Hg total pressure (where collisional deactivation is insignificant), suggesting that collisional deactivation was not of major importance even at the pressure used in the present work. In order to account for the high translational–rotational temperature, in the absence of substantial vibrational deactivation, it was necessary to suppose that the greater part of the energy liberated by the reaction H + Cl2 went directly into translational and rotational motion of the products.

Investigation of Resonances in the Scattering of a Heavy ‘Positron’ by H2 that Involve Vibrationally Excited Quasi-Bound States

2010 ◽  
Vol 666 ◽  
pp. 25-30
Author(s):  
Edward A.G. Armour
Keyword(s):  
Variational Method ◽  
Bound States ◽  
Low Energy ◽  
Annihilation Rate ◽  
Effective Number ◽  
Feshbach Resonances ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Positron Scattering ◽  
Very High

There is currently great interest in the very large values of the positron annihilation rate that have been observed in low-energy positron scattering by some molecules. The annihilation rate is proportional to , the effective number of electrons in the target available to the positron for annihilation. These very high rates and associated values of have been observed experimentally to occur at energies just below the energies of excited vibrational states of the molecule concerned. This has been explained by Gribakin [Phys. Rev. A Vol. 61 (2000), p. 022720] and Gribakin and Lee [Phys. Rev. Lett. Vol. 97 (2006), p. 193201] as being due to Feshbach resonances involving excited quasi-bound vibrational states. Their explanation is partly phenomenological. In this paper, I describe the results of an ab initio treatment of this resonant behaviour in the case of the scattering of a heavy ‘positron’ by , using the Kohn variational method.

scholarly journals The Microwave Spectrum of Excited Vibrational States of CF3NC

1984 ◽  
Vol 39 (9) ◽  
pp. 865-870 ◽  
Author(s):  
Dines Christen ◽  
Klaus-J. Ramme
Keyword(s):  
Perturbation Theory ◽  
Force Field ◽  
Microwave Spectrum ◽  
Interaction Parameters ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Rotational Spectra ◽  
Degenerate States ◽  
Vibration Rotation ◽  
Good Agreement

The rotational spectra of vibrationally excited CF3NC states (ν4, ν6, ν7, ν8, 2ν8 and 3ν8) have been recorded and analyzed for the transitions J: 1→2, 2→3 and 3→4 using (for the degenerate states) a simplified frequency expression based on perturbation theory. The following vibration/rotation interaction parameters were derived (in MHz): α4: 0.145, α6: - 5.585, q+6 4.241, α7: 2.350, q+7: 1.438, α8: - 10.610, and q+8: 5.101. The Coriolis constant ζÀ88 was determined to be 0.672 in good agreement with the value calculated from the force field.

Nascent HF† and HSO(2A′) formations in the elementary reactions of F + H2S and HS + O3 and the internal energy distributions

1995 ◽  
Vol 73 (2) ◽  
pp. 204-211 ◽  
Author(s):  
Yasunori Yoshimura ◽  
Toshio Kasai ◽  
Hiroshi Ohoyama ◽  
Keiji Kuwata
Keyword(s):  
Internal Energy ◽  
Rotational Temperature ◽  
Similar Data ◽  
Vibrational States ◽  
Energy Distributions ◽  
Vibrationally Excited ◽  
Elementary Reactions ◽  
Electronically Excited ◽  
Vibrational Bands ◽  
Rotational Distribution

Chemiluminescence of the vibrationally excited HF† and of the electronically excited HSO* in the 2A′ state were observed in the elementary reactions of F + H2S and HS + O3. In the F + H2S reaction, the vibrational populations of HF† in ν = 3 and 4 were found to be nonstatistical but the rotational distribution in the ν = 4 state was found to be Boltzmann-like with a rotational temperature of 700 K, confirming similar data obtained by different methods. The HSO* emission was observed in the HS + O3 elementary reaction. The spectrum of HSO* characterized by broad vibrational bands indicates nonstatistical excitation for the rotational and vibrational states. Keywords: chemiluminescence, internal energy distribution, F + H2S, HS + O3, HF†, HSO*.

Microwave Spectrum of Chloroacetylene in Ground and Excited Vibrational States

1978 ◽  
Vol 33 (2) ◽  
pp. 156-163 ◽  
Author(s):  
Harold Jones ◽  
Michio Takami ◽  
John Sheridan
Keyword(s):  
Excited States ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Spectroscopic Constants ◽  
Frequency Range ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Rotational Spectra ◽  
Isotopic Species ◽  
Quadrupole Coupling

The microwave spectrum of chloroacetylene in the ground and excited states has been investigated in the frequency range 15 to 306 GHz. Ground state rotational and nuclear quadrupole coupling constants for twelve isotopic species of chloroacetylene and accurate distortion constants were determined for two of these. The data allowed the rs-structure of chloroacetylene to be reconsidered and the internal consistency of this method of structure determination to be checked. Rotational spectra in five vibrationally excited states, with energy up to 700 cm-1 were observed for four different isotopic species and spectroscopic constants for these states were derived.

The reaction of hydrogen atoms with propylene

1971 ◽  
Vol 324 (1559) ◽  
pp. 433-446 ◽  
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Flow System ◽  
Primary Process ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Flow Rates ◽  
Detailed Mechanism ◽  
Excited Species

A detailed study has been made of the products of the reaction of hydrogen atoms with propylene. A discharge-flow system at 290±3 K was used. Total pressures in the range 4 to 16 Torr (550 to 2200 N m -2 ) of argon were used and the flow rates of hydrogen atoms and propylene ranged individually up to about 12 μ mol s -1 . As found by others the main products are methane, ethane, ethylene, propane and isobutane. Trivial amounts of 2,3-dimethylbutane, but no n-butane, were detected. A detailed mechanism accounting adequately for the reaction is proposed. It is confirmed that formation of the vibrationally excited species, i-C 3 H 7 *, is the predominant primary process. Novel processes which are shown to be important are H+i-C 3 H 7 * → CH 3 +C 2 H 5 and, C 3 H 8 * → CH 4 +C 2 H 4 . A number of rate constant ratios have been evaluated from the data and these allow calculation of absolute rate constants of some individual reactions. The agreement with previously reported values is, in most instances, good.

State- and bond-selected photodissociation and bimolecular reaction of water

1990 ◽  
Vol 332 (1625) ◽  
pp. 259-272 ◽  
Keyword(s):  
Room Temperature ◽  
Reaction Dynamics ◽  
Bimolecular Reaction ◽  
Water Molecules ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
Stretching Vibration ◽  
Different Populations ◽  
H 20 ◽  
Selection Of

It is possible to exploit the isolation of the 0 —H stretching vibration in H 20 and HOD to control the photodissociation and reaction dynamics in water molecules excited in the region of the third overtone (4rOH) of the 0 -H stretch. In vibrationally mediated photodissociation of H 20, the selection of different initial stretching states having roughly the same energy leads to drastically different populations of the vibrational states of the OH photolysis product. By exciting the O-H stretching overtone in HOD, we can selectively photolyze that bond. In bimolecular reaction experiments, we react H 20 (4rOH) with H atoms to produce H 2 and OH. The reaction, which is endothermic, proceeds at an undetectable rate in our room temperature measurements. Vibrationally excited water, however, reacts at roughly the gas kinetic collision rate. Applying this technique to HOD (4rOH) allows us to demonstrate bond selected bimolecular chemistry in which the reaction produces only OD. This observation suggests a general approach to assessing bond controlled reactions in a variety of systems.

The reaction of hydrogen atoms with isobutene

1971 ◽  
Vol 324 (1559) ◽  
pp. 447-458 ◽  
Keyword(s):  
Rate Constants ◽  
Reaction System ◽  
Primary Process ◽  
Absolute Rate ◽  
Hydrogen Atoms ◽  
Vibrationally Excited ◽  
Flow Rates ◽  
Detailed Mechanism ◽  
Product Distributions ◽  
Excited Species

A detailed study has been made of the products of the reaction of hydrogen atoms with isobutene in a discharge flow reaction system at 290±3 K. Total pressures in the range 4 to 12 Torr (550 to 1650 N m -2 ) of argon were used and flow rates of hydrogen atoms and isobutene ranged individually up to about 10 μ mol s -1 . The main products were methane, ethane, ethylene, propane, propylene, isobutane and neopentane. A detailed mechanism accounting adequately for the observed product distributions and their dependence upon pressure and reactant mixture composition is proposed. The formation of the vibrationally excited species t-C 4 H 9 * is shown to be the predominant primary process. A number of rate constant ratios have been evaluated and absolute rate constants for some individual reactions have been estimated from the data. Some of the details of an earlier analogous study of the reaction of hydrogen atoms with propylene have been confirmed and some interesting correlations are indicated.

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