Determination of the gas temperatures of a low-pressure plasma from the intensities of the H/sub 2/ and D/sub 2/ molecular bands; rotational transitions under electron-impact excitation
An estimate of the cross sections of rotational transitions occurring when the electronic states of molecules are excited by electron impact is proposed. Initially a zero-radius potential model is used in the adiabatic molecular rotation approximation. Then additional arguments in favor of the generality of the estimate obtained are carried out, which are similar to the Franck-Condon principle but relate to the rotational transitions. For diatomic homonuclear molecules, the form of the cross sections of the /sup 2S/+1..lambda../sup + -//sub u/, v, Nreverse arrow/sup 1/..sigma../sup +//sub g/, v/sub 0/, N/sub 0/ transitions is derived, which allows us to estimate the cross sections in terms of the intensities measured in a low pressure plasma of the spectral lines of the Q-branches of the Fulcher band system of the H/sub 2/ molecule. Satisfactory agreement between theory and experiment is observed. It is shown that at low energies of the incoming electrons the cross section drops rapidly with an increase of the change of the rotational quantum number N; therefore, transitions with ..delta..N=0, /sup + -/1 dominate in a low-temperature gas-discharge plasma. This result is a necessary prerequisite for the justification of the method of measurement of the gas temperature of the low pressure plasma in terms of the intensities of the molecular bands.
- OSTI ID:
- 5568102
- Journal Information:
- Opt. Spectrosc. (USSR) (Engl. Transl.); (United States), Vol. 47:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DEUTERIUM
ELECTRON-MOLECULE COLLISIONS
EXCITATION
HYDROGEN
PLASMA DIAGNOSTICS
CROSS SECTIONS
LIMITING VALUES
ROTATIONAL STATES
TEMPERATURE MEASUREMENT
COLLISIONS
CRYOGENIC FLUIDS
ELECTRON COLLISIONS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
STABLE ISOTOPES
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena
700102 - Fusion Energy- Plasma Research- Diagnostics