Thermal dissociation of diatomic molecules in a nonisothermal boundary layer in the presence of exchange reactions

1995 ◽  
Vol 30 (1) ◽  
pp. 133-141
Author(s):  
V. I. Nosik ◽  
E. A. Rastigeev
Keyword(s):  
Boundary Layer ◽  
Diatomic Molecules ◽  
Thermal Dissociation ◽  
Exchange Reactions

scholarly journals A broadband cavity ringdown spectrometer for in-situ measurements of atmospheric trace gases

2005 ◽  
Vol 5 (3) ◽  
pp. 3491-3532 ◽  
Author(s):  
M. Bitter ◽  
S. M. Ball ◽  
I. M. Povey ◽  
R. L. Jones
Keyword(s):  
Boundary Layer ◽  
Water Vapour ◽  
Marine Boundary Layer ◽  
Thermal Dissociation ◽  
Optical Absorption Spectroscopy ◽  
Integration Time ◽  
Research Station ◽  
Absorption Bands ◽  
Optical Extinction ◽  
Cavity Ringdown

Abstract. This paper describes a broadband cavity ringdown spectrometer and its deployment during the 2002 North Atlantic Marine Boundary Layer Experiment (NAMBLEX) to measure ambient concentrations of NO3, N2O5, I2 and OIO at the Mace Head Atmospheric Research Station, Co. Galway, Ireland. The effective absorption path lengths accessible with the spectrometer generally exceeded 10 km, enabling sensitive localised ''point'' measurements of atmospheric absorbers to be made adjacent to the other instruments monitoring chemically related species at the same site. For the majority of observations, the spectrometer was used in an open path configuration thereby avoiding surface losses of reactive species. A subset of observations targeted the N2O5 molecule by detecting the additional NO3 formed by the thermal dissociation of N2O5. In all cases the concentrations of the atmospheric absorbers were retrieved by fitting the differential structure in the broadband cavity ringdown spectra using a methodology adapted from long path differential optical absorption spectroscopy. The uncertainty of the retrieval depends crucially on the correct treatment and fitting of the absorption bands due to water vapour, a topic that is discussed in the context of analysing broadband cavity ringdown spectra. The quality of the measurements and the retrieval method are illustrated with representative spectra acquired during NAMBLEX in spectral regions around 660 nm (NO3 and N2O5) and 570 nm (I2 and OIO). Typical detection limits were 1 pptv for NO3 in an integration time of 100 s, 4 pptv for OIO and 20 pptv for I2 in an integration time of 10 min. Additionally, the concentrations of atmospheric water vapour and the aerosol optical extinction were retrieved in both spectral regions. A companion paper in this issue presents the time series of the measurements and discusses their significance for understanding the variability of short lived nitrogen and iodine compounds in the marine boundary layer.

The noneouilibrium dissociation of diatomic molecules in a boundary layer

1985 ◽  
Vol 20 (1) ◽  
pp. 139-148 ◽  
Author(s):  
N. K. Makashev ◽  
V. P. Provotorov
Keyword(s):  
Boundary Layer ◽  
Diatomic Molecules

Simultaneous vibrational relaxation and thermal dissociation of diatomic molecules

1971 ◽  
Vol 4 (3) ◽  
pp. 200-202 ◽  
Author(s):  
N. A. Generalov ◽  
B. V. Kuksenko ◽  
S. A. Losev ◽  
A. I. Osipov
Keyword(s):  
Vibrational Relaxation ◽  
Diatomic Molecules ◽  
Thermal Dissociation

scholarly journals EFFECT OF MASS TRANSFER OF SYSTEMS Mn(Fe,Co)Mo(W)O4–Na2CO3 AND ENVIRONMENT AND NEED FOR HIS ACCOUNT WHEN IDENTIFYING MOLYBDATES AND TUNGSTATES OF MULTIVALENT d-ELEMENTS, Mn, Fe, Co, ON BASIS OF THERMOGRAVIMETRIC DATA

2019 ◽  
Vol 62 (4) ◽  
pp. 111-120 ◽  
Author(s):  
Gazali K. Shurdumov ◽  
Zaur A. Cherkesov ◽  
Laura I. Mokaeva
Keyword(s):  
Mass Transfer ◽  
Degradation Products ◽  
Thermal Dissociation ◽  
Calculated Data ◽  
Exchange Reactions ◽  
Thermogravimetric Data ◽  
Analysis And Synthesis ◽  
Reasonable Choice ◽  
First Time ◽  
Derivatives Of

The paper presents the experimental and calculated data for study of exchange reactions in the systems Mn(Fe,Co)Mo(W)O4–Na2CO3 with methods of thermodynamics, thermogravimetry, kinetics topochemically reactions and stoichiometry, analysis and synthesis which led to the identification of the effect of mass transfer between the system and the environment – a phenomenon characteristic of molybdates (tungstates) polyvalent d-elements (Mn,Fe,Co) in contrast to similar derivatives of d-elements (Ni, Zn, Cd, Ag) with constant valency. It identified the genesis and the mechanism of manifestation of this phenomenon, which, as shown by theoretical analysis and experimental data, due to polivalentes Mn (Fe,Co) and hence the possibility of occurrence in the systems Mn(Fe,Co)Mo(W)O4–Na2CO3 exchange reactions of Mn(Fe, Co)Mo(W)O4+Na2CO3→ →Mn(Fe,Co)CO3+Na2Mo(W)O4, dissociation of Mn(Fe,Co)CO3=Mn(Fe,Co)O+CO2 and redox Mn(Fe,Co)O+1/2О2→Mnx(Feх,Cox)Oy where y=x+1/2О2, leading to the loss of CO2 and the conversion of Mn(Fe,Co)O – degradation products of Mn(Fe,Co)CO3 at the expense of the oxygen of environment to the oxide type-Mnx(Feх,Cox)Oy, the composition of which is determined by the process temperature. It is established that the above reactions form the basis of the unique phenomenon in solid state chemistry of molibdates (wolframates) of polyvalent d-elements discovered for the first time, in the opinion of the authors. This phenomenon is associated with the proceeding of Mn(Fe,Co)Mo(W)O4–Na2CO3 processes in their heat treatment. It is shown that successive thermal dissociation reactions of Mn(Fe,Co)CO3 lead to their loss of CO2 (mass reduction) and oxidation of the formed Mn(Fe,Co)O by air oxygen to Mnх(Feх,Coх)Oу=x+1/2О2 (mass growth): CO2 donor systems and O2 acceptors, and the medium (air) – O2 donor and CO2 acceptor. The proposed methodology is a reasonable choice of the reaction from the expected, the occurrence of which is absolutely reliable in given physicochemical conditions.

Thermal dissociation of diatomic molecules

1972 ◽  
Vol 5 (4) ◽  
pp. 301-304
Author(s):  
E. A. Pshenichnov ◽  
A. S. Shustov
Keyword(s):  
Diatomic Molecules ◽  
Thermal Dissociation

Birefringence in the Boundary Layer of a Rarefied Heat Conducting Gas

1981 ◽  
Vol 36 (6) ◽  
pp. 579-583
Author(s):  
P. Oudeman ◽  
J. Korving ◽  
H. F. P. Knaap ◽  
J. J. M. Beenakker
Keyword(s):  
Boundary Layer ◽  
Diatomic Molecules ◽  
Heat Conducting ◽  
Parallel Plates ◽  
Tensor Polarization ◽  
Angular Momenta ◽  
Rank Tensor

Abstract In a heat conducting gas of diatomic molecules enclosed between parallel plates, the second rank tensor polarization of the rotational angular momenta can be shown to be nonzero in a boundary layer near the plates, a few mean free paths thick. This phenomenon can be experimentally studied by measuring the birefringence of the boundary layer. Although the predicted effects are very small (An of the order of 10-14), the existence of this effect is clearly demonstrated and qualitative results are obtained for N2, CO and HD

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