Mechanism of a CO–N2 laser. I. Study of the vibrational populations

1970 ◽  
Vol 48 (17) ◽  
pp. 1949-1955 ◽  
Author(s):  
F. Legay ◽  
N. Legay-Sommaire ◽  
G. Taïeb
Keyword(s):  
Infrared Spectroscopy ◽  
Population Inversion ◽  
Laser Level ◽  
Laser Line ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Operational Characteristics ◽  
Gain Measurement ◽  
Vibrational Levels ◽  
Excited Nitrogen

A laser operating on the vibrational–rotational levels of CO populated by active nitrogen has been built and studied by infrared spectroscopy. The operational characteristics and the importance of the nature of the walls and their condition are discussed. The population of each vibrational laser level has been deduced from the gain measurement of each laser line. The mechanism of the population inversion is described in terms of the theory proposed by Treanor, Rich, and Rehm, assuming that the population of CO vibrational levels is ensured by a vibration–vibration transfer from vibrationally excited nitrogen molecules.

THE REACTIVE SPECIES IN ACTIVE NITROGEN

1962 ◽  
Vol 40 (6) ◽  
pp. 1082-1097 ◽  
Author(s):  
A. N. Wright ◽  
R. L. Nelson ◽  
C. A. Winkler
Keyword(s):  
Molecular Nitrogen ◽  
Reaction Vessel ◽  
Active Nitrogen ◽  
Atom Concentration ◽  
Vibrational Levels ◽  
Long Lifetime ◽  
Excited Nitrogen ◽  
A Minor ◽  
Hydrocarbon Reactions ◽  
Decomposition Of No

A study has been made of the discrepancy between the N-atom content of active nitrogen as inferred from the maximum HCN production from the reaction of many hydrocarbons, and that indicated by the extent of NO destruction. The HCN production from several hydrocarbons was similar at high reaction temperatures in a spherical reaction vessel, and was independent of reaction temperature in a cylindrical reaction vessel. The ratio (NO destroyed)/(HCN produced) was found to be independent of the mode of excitation òf the molecular nitrogen and of the N-atom concentration, and to be unaffected by the addition, upstream, of N2O or CO2. Although NH3 was found to be a minor product of the hydrocarbon reactions, HCN accounted for at least 96% of the N-atom content of the products under conditions where its formation is considered a measure of the N-atom concentration. The NO "titration" value, the maximum extent of HCN production from C2H4, and the destruction of NH3 after different times of decay of active nitrogen gave evidence that part of the NO reaction occurred, as does the NH3 reaction, with excited nitrogen molecules. The long lifetime of the N2* species capable of reaction with NO or NH3, as calculated from the above data, strongly favors its identification as low vibrational levels of the N2(A3∑u+) molecule. A consideration of the values for the NO/HCN, NH3/HCN, and NH3/NO ratios, after different times of decay, for poisoned and unpoisoned systems, suggested that the N2* responsible for the NH3 reaction is formed only during homogeneous recombination of N atoms, while the N2* responsible for reaction with NO might be produced by wall recombination as well. Possible reactions of excited molecules present in the active nitrogen – NO system that might lead to decomposition of NO without consumption of N atoms are discussed.

scholarly journals The role of vibrationally excited nitrogen and oxygen in the ionosphere over Millstone Hill during 16-23 March, 1990

2000 ◽  
Vol 18 (8) ◽  
pp. 957-966
Author(s):  
A. V. Pavlov ◽  
K.-I. Oyama
Keyword(s):  
Electron Density ◽  
Boltzmann Distribution ◽  
Ion Chemistry ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
Maximum Value ◽  
Vibrational Levels ◽  
Electron Density And Temperature ◽  
Excited Nitrogen ◽  
Distribution Assumption

Abstract. We present a comparison of the observed behavior of the F region ionosphere over Millstone Hill during the geomagnetically quiet and storm period on 16-23 March, 1990, with numerical model calculations from the time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The effects of vibrationally excited N2(v) and O2(v) on the electron density and temperature are studied using the N2(v) and O2(v) Boltzmann and non-Boltzmann distribution assumptions. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v) and O2(v) were calculated. The present study suggests that these deviations are not significant at vibrational levels v = 1 and 2, and the calculated distributions of N2(v) and O2(v) are highly non-Boltzmann at vibrational levels v > 2. The N2(v) and O2(v) non-Boltzmann distribution assumption leads to the decrease of the calculated daytime NmF2 up to a factor of 1.44 (maximum value) in comparison with the N2(v) and O2(v) Boltzmann distribution assumption. The resulting effects of N2(v > 0) and O2(v > 0) on the NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2.8 (maximum value) for Boltzmann populations of N2(v) and O2(v) and up to a factor of 3.5 (maximum value) for non-Boltzmann populations of N2(v) and O2(v) . This decrease in electron density results in the increase of the calculated daytime electron temperature up to about 1040-1410 K (maximum value) at the F2 peak altitude giving closer agreement between the measured and modeled electron temperatures. Both the daytime and nighttime densities are not reproduced by the model without N2(v > 0) and O2(v > 0) , and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement. The effects of vibrationally excited O2 and N2 on the electron density and temperature are most pronounced during daytime.Key words: Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions; ionospheric disturbances)

THE STUDY OF VIBRATIONALLY EXCITED N2 MOLECULES WITH THE AID OF AN ISOTHERMAL CALORIMETER

1963 ◽  
Vol 41 (4) ◽  
pp. 903-912 ◽  
Author(s):  
J. E. Morgan ◽  
H. I. Schiff
Keyword(s):  
Microwave Discharge ◽  
Reaction Vessel ◽  
Kcal Mole ◽  
Collision Efficiency ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
First Case ◽  
Nitrogen Stream ◽  
Excited Nitrogen ◽  
Isothermal Calorimeter

Vibrationally excited nitrogen molecules produced both by a microwave discharge in nitrogen and also by the reaction[Formula: see text]have been examined using an isothermal calorimetric probe.In the first case the energy associated with an 'active' nitrogen stream, due to vibrationally excited N2, was found to be 6.03 kcal mole−1 of total nitrogen. The subsequent relaxation of this species was found to occur almost entirely on the walls of the reaction vessel, with a collision efficiency of 4.5 × 10−4. The addition of other gases greatly accelerated the homogeneous relaxation rate. Collisional efficiencies of N2O, CO2, and Ar were found to be 0.8 × l0−4, 2.3 × 10−5, and 1.0 × 10−6 respectively.The vibrationally excited nitrogen produced by the N/NO reaction was found to possess 20 ± 4 kcal mole−1 of energy compared with the maximum of 75 kcal mole−1 allowed by the exothermicity of the reaction.

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.

Molecules in strong laser fields: vibrational inversion and harmonic generation

1994 ◽  
Vol 72 (3) ◽  
pp. 673-677 ◽  
Author(s):  
Eric E. Aubanel ◽  
André D. Bandrauk
Keyword(s):  
Harmonic Generation ◽  
Laser Pulses ◽  
Harmonic Spectrum ◽  
Femtosecond Laser Pulses ◽  
Generation Process ◽  
High Order Harmonic Generation ◽  
Vibrationally Excited ◽  
Potential Wells ◽  
High Order Harmonic ◽  
Vibrational Levels

We examine two consequences of the unique behaviour of molecules in strong fields. First, by time gating of laser-induced avoided crossings with femtosecond laser pulses, one can obtain efficient vibrational inversion into a narrow distribution of vibrational levels of a molecular ion. We demonstrate this by numerical solution of the time-dependent Schrödinger equation for [Formula: see text] Second, we show results of numerical calculation with vibrationally excited [Formula: see text] of harmonic generation up to the 11th order of an intense 1064- nm laser. We predict that competition of photodissociation can be minimized by trapping the molecule in high-field-induced potential wells, thus enhancing the high-order harmonic generation process. Furthermore, the harmonic spectrum can serve as a measure of the structure of these laser-induced potentials.

The microwave spectrum of the OH X2Π radical in the ground and vibrationally-excited (ν ≤ 6) levels

1979 ◽  
Vol 57 (5) ◽  
pp. 619-634 ◽  
Author(s):  
J. A. Coxon ◽  
K. V. L. N. Sastry ◽  
J. A. Austin ◽  
D. H. Levy
Keyword(s):  
Absorption Spectrum ◽  
Parallel Plate ◽  
Microwave Spectrum ◽  
Hamiltonian Matrix ◽  
Centrifugal Distortion ◽  
Linear Least Squares ◽  
Vibrationally Excited ◽  
Hyperfine Constants ◽  
Vibrational Levels ◽  
Astrophysical Significance

The microwave absorption spectrum of the OH X2Π radical has been observed in all vibrational levels up to ν = 6. Experimental details are described of the tunable cavity and parallel plate Stark-modulated spectrometers employed for transitions below and above 23 GHz, respectively. The observed line frequencies, together with those reported by other workers, have been fitted using a non-linear least-squares routine with numerical diagonalization of the Hamiltonian matrix. Pseudo high-order corrections for centrifugal distortion of the Λ-doubling are required for the ν = 0 data, which now extend to J = 19/2 in the 2Π1/2 component. The various adjustable parameters of the Hamiltonian are compared with those of other similar models. The Λ-doubling and magnetic hyperfine constants for the different vibrational levels are reported, and several line frequencies of potential astrophysical significance are predicted.

scholarly journals Subauroral red arcs as a conjugate phenomenon: comparison of OV1-10 satellite data with numerical calculations

1997 ◽  
Vol 15 (8) ◽  
pp. 984-998 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electron Density ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Atomic Oxygen ◽  
Major Ions ◽  
Integral Intensity ◽  
Rate Coefficients ◽  
Vibrationally Excited ◽  
Vibrational Distribution ◽  
Vibrational Levels

Abstract. This study compares the OV1-10 satellite measurements of the integral airglow intensities at 630 nm in the SAR arc regions observed in the northern and southern hemisphere as a conjugate phenomenon, with the model results obtained using the time-dependent one-dimensional mathematical model of the Earth ionosphere and plasmasphere (the IZMIRAN model) during the geomagnetic storm of the period 15–17 February 1967. The major enhancements to the IZMIRAN model developed in this study are the inclusion of He+ ions (three major ions: O+, H+, and He+, and three ion temperatures), the updated photochemistry and energy balance equations for ions and electrons, the diffusion of NO+ and O2+ ions and O(1D) and the revised electron cooling rates arising from their collisions with unexcited N2, O2 molecules and N2 molecules at the first vibrational level. The updated model includes the option to use the models of the Boltzmann or non-Boltzmann distributions of vibrationally excited molecular nitrogen. Deviations from the Boltzmann distribution for the first five vibrational levels of N2 were calculated. The calculated distribution is highly non-Boltzmann at vibrational levels v > 2 and leads to a decrease in the calculated electron density and integral intensity at 630 nm in the northern and southern hemispheres in comparison with the electron density and integral intensity calculated using the Boltzmann vibrational distribution of N2. It is found that the intensity at 630 nm is very sensitive to the oxygen number densities. Good agreement between the modelled and measured intensities is obtained provided that at all altitudes of the southern hemisphere a reduction of about factor 1.35 in MSIS-86 atomic oxygen densities is included in the IZMIRAN model with the non-Boltzmann vibrational distribution of N2. The effect of using of the O(1D) diffusion results in the decrease of 4–6% in the calculated integral intensity of the northern hemisphere and 7–13% in the calculated integral intensity of the southern hemisphere. It is found that the modelled intensities of the southern hemisphere are more sensitive to the assumed values of the rate coefficients of O+(4S) ions with the vibrationally excited nitrogen molecules and quenching of O+(2D) by atomic oxygen than the modelled intensities of the northern hemisphere.

scholarly journals The role of vibrationally excited oxygen and nitrogen in the ionosphere during the undisturbed and geomagnetic storm period of 6-12 April 1990

1998 ◽  
Vol 16 (5) ◽  
pp. 589-601 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Loss Rate ◽  
Boltzmann Distribution ◽  
Rate Coefficients ◽  
Ion Chemistry ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
F Region ◽  
Neutral Temperature ◽  
The Difference ◽  
Excited Nitrogen

Abstract. We present a comparison of the observed behavior of the F-region ionosphere over Millstone Hill during the geomagnetically quiet and storm periods of 6–12 April 1990 with numerical model calculations from the IZMIRAN time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The major enhancement to the IZMIRAN model developed in this study is the use of a new loss rate of O+(4S) ions as a result of new high-temperature flowing afterglow measurements of the rate coefficients K1 and K2 for the reactions of O+(4S) with N2 and O2. The deviations from the Boltzmann distribution for the first five vibrational levels of O2(v) were calculated, and the present study suggests that these deviations are not significant. It was found that the difference between the non-Boltzmann and Boltzmann distribution assumptions of O2(v) and the difference between ion and neutral temperature can lead to an increase of up to about 3 or a decrease of up to about 4 of the calculated NmF2 as a result of a respective increase or a decrease in K2. The IZMIRAN model reproduces major features of the data. We found that the inclusion of vibrationally excited N2(v > 0) and O2(v > 0) in the calculations improves the agreement between the calculated NmF2 and the data on 6, 9, and 10 April. However, both the daytime and nighttime densities are reproduced by the IZMIRAN model without the vibrationally excited nitrogen and oxygen on 8 and 11 April better than the IZMIRAN model with N2(v > 0) and O2(v > 0). This could be due to possible uncertainties in model neutral temperature and densities, EUV fluxes, rate coefficients, and the flow of ionization between the ionosphere and plasmasphere, and possible horizontal divergence of the flux of ionization above the station. Our calculations show that the increase in the O+ + N2 rate factor due to N2(v > 0) produces a 5-36 decrease in the calculated daytime peak density. The increase in the O++ O2 loss rate due to vibrational-ly excited O2 produces 8-46 reductions in NmF2. The effects of vibrationally excited O2 and N2 on Ne and Te are most pronounced during the daytime.Key words. Ion chemistry and composition · Ionosphere – atmosphere interactions · Ionospheric disturbances

Deactivation of vibrationally excited nitrogen molecules by collision with nitrogen atoms

1987 ◽  
Vol 91 (2) ◽  
pp. 312-314 ◽  
Author(s):  
A. Lagana ◽  
E. Garcia ◽  
L. Ciccarelli
Keyword(s):  
Vibrationally Excited ◽  
Excited Nitrogen

Vibrationally excited nitrogen in stable auroral red arcs and its effect on ionospheric recombination

1974 ◽  
Vol 79 (25) ◽  
pp. 3807-3818 ◽  
Author(s):  
George P. Newton ◽  
James C. G. Walker ◽  
P. H. E. Meijer
Keyword(s):  
Vibrationally Excited ◽  
Excited Nitrogen
Sign in / Sign up

Export Citation Format

Share Document