Balmer-series fluorescence from photodissociation fragments of H/sub 2/ and D/sub 2/. [cross sections]

Journal Article · Wed Sep 01 04:00:00 EDT 1976 · Phys. Rev., A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.14.1094· OSTI ID:7178737

Lee, L C; Judge, D L

The photodissociation processes of H/sub 2/ and D/sub 2/ have been studied using photon wavelengths in the lambdalambda686--723-A region. The fluorescence radiation from the photofragments was dispersed in the lambdalambda3500--7000-A region and was identified as the Balmer series. The cross sections for the production of the Balmer series were measured and were used to infer the cross sections for the photodissociation of H/sub 2/ and D/sub 2/ into atomic products in the n > or = 3 levels. The dependence of the cross sections for the production of excited atoms in the n levels on the excess kinetic energy is, in general, similar to that in the n = 2 level calculated by Allison and Dalgarno. The photodissociation process is therefore attributed mainly to the direct photoexcitation of molecules from the ground state into continua. This suggestion is further strengthened by the fact that the ratio of the cross sections for production of atoms formed in the n = 4 and 5 levels agrees with that of the square of their transition moments calculated by Rothenburg and Davidson. However, the ratio of the cross sections between the n = 3 and 4 levels does not agree well with the same calculation. It is therefore inferred that the cross section for the production of atoms excited in the n = 3 level may be partially through predissociation processes. This observation is consistent with the theoretical prediction of Berry and Nielsen that photodissociation of H/sub 2/ into H(1s) + H(nl, n > or = 3) through predissociation is only important in the n = 3 channel. (AIP)

• Research Organization: Department of Physics, University of Southern California, Los Angeles, California 90007
• OSTI ID: 7178737
• Journal Information: Phys. Rev., A; (United States), Journal Name: Phys. Rev., A; (United States) Vol. 14:3; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
BALMER LINES
COLLISIONS
CRYOGENIC FLUIDS
DEUTERIUM
DISSOCIATION
ELEMENTS
FLUIDS
FLUORESCENCE
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
LUMINESCENCE
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
PHOTON COLLISIONS
PHOTON-MOLECULE COLLISIONS
STABLE ISOTOPES