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UBC Theses and Dissertations
Hyperfine structure and predissociation of the B ³[pi]₀ + state of bromine Booth, James L.
Abstract
Investigations have been carried out in bromine of the hyperfine structure of the B ³II₀u+ and X ¹Σg⁺ electronic states and of the predissociation of the B ³ll₀u+ state by the ¹ll₁u dissociative level. The technique of laser induced fluorescence of a molecular beam was used. ⁷⁹Br⁸¹Br hyperfine spectra were recorded for various B - X vibrational bands (v’ ←v”) with v’ = 11 through 17 and v” = 0, 1, and 2, and for various rotational transitions (J’ ← J”) with J’ from 0 to 11 and J” from 0 to 10. As well, the ⁷⁹Br₂ and ⁸¹Br₂ hyperfine spectra of the (13’ — 0”) and (17’ — 2”) bands over the same range of rotational states were measured. The spectra are well described using one X state parameter: the electric quadrupole coupling constant eqQx; and two B state parameters: the electric quadrupole coupling constant eqQB, and the nuclear spin-rotation constant Csr. The results show that eqQB(⁷⁹Br) = (177.0 ± 0.6) MHz for v’ = 11 and increases by approximately 0.5 MHz per vibrational quantum up to (180.6 ± 1.4) MHz for v’ 17. Similarly the ground state electric quadrupole coupling constant, eqQx(⁷⁹Br) (808.1 ± 1.4) MHz for v” = 0 and increases by about 1 MHz per vibrational quantum to (811.4 ± 1.4) MHz for v” = 2. The hyperfine data also provided a check on the accuracy of some of the published rovibronic constant¹ for each isotopomer. In order to reproduce the observed relative spacings of the transitions for all three isotopomers, the published term values, T₀₀, have to be modified ; this can be done by decreasing the published values of T₀₀ for ⁸¹Br₂ and ⁷⁹Br⁸¹Br by (177 ± 8) MHz and (326 ± 8) MHz, respectively. The phase shift technique was applied to the study of the predissociation of the v’ = 13 B ³II₀u⁺ electronic state of bromine. The lifetimes of individual hyperfine levels were ¹S. Gerstenkorn and P. Luc, J. Phys. France 50, 1417 (1989). measured for the rotational states J’ = 0 - 7 (except for J’ 2) for each isotopomer of bromine. Revised values are given for the radiative decay rate Γrad, the gyroscopic predissociation parameter Cv, and the magnetic dipole predissociation parameter av. The first observation of electric quadrupole predissociation is reported and is characterized by a new molecular parameter, bv.
Item Metadata
Title |
Hyperfine structure and predissociation of the B ³[pi]₀ + state of bromine
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
Investigations have been carried out in bromine of the hyperfine structure of the B ³II₀u+
and X ¹Σg⁺ electronic states and of the predissociation of the B ³ll₀u+ state by the ¹ll₁u
dissociative level. The technique of laser induced fluorescence of a molecular beam was
used. ⁷⁹Br⁸¹Br hyperfine spectra were recorded for various B - X vibrational bands
(v’ ←v”) with v’ = 11 through 17 and v” = 0, 1, and 2, and for various rotational
transitions (J’ ← J”) with J’ from 0 to 11 and J” from 0 to 10. As well, the ⁷⁹Br₂
and ⁸¹Br₂ hyperfine spectra of the (13’ — 0”) and (17’ — 2”) bands over the same range
of rotational states were measured. The spectra are well described using one X state
parameter: the electric quadrupole coupling constant eqQx; and two B state parameters:
the electric quadrupole coupling constant eqQB, and the nuclear spin-rotation constant
Csr. The results show that eqQB(⁷⁹Br) = (177.0 ± 0.6) MHz for v’ = 11 and increases
by approximately 0.5 MHz per vibrational quantum up to (180.6 ± 1.4) MHz for v’
17. Similarly the ground state electric quadrupole coupling constant, eqQx(⁷⁹Br)
(808.1 ± 1.4) MHz for v” = 0 and increases by about 1 MHz per vibrational quantum to
(811.4 ± 1.4) MHz for v” = 2. The hyperfine data also provided a check on the accuracy
of some of the published rovibronic constant¹ for each isotopomer. In order to reproduce
the observed relative spacings of the transitions for all three isotopomers, the published
term values, T₀₀, have to be modified ; this can be done by decreasing the published
values of T₀₀ for ⁸¹Br₂ and ⁷⁹Br⁸¹Br by (177 ± 8) MHz and (326 ± 8) MHz, respectively.
The phase shift technique was applied to the study of the predissociation of the v’ =
13 B ³II₀u⁺ electronic state of bromine. The lifetimes of individual hyperfine levels were
¹S. Gerstenkorn and P. Luc, J. Phys. France 50, 1417 (1989).
measured for the rotational states J’ = 0 - 7 (except for J’ 2) for each isotopomer
of bromine. Revised values are given for the radiative decay rate Γrad, the gyroscopic
predissociation parameter Cv, and the magnetic dipole predissociation parameter av. The
first observation of electric quadrupole predissociation is reported and is characterized
by a new molecular parameter, bv.
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Extent |
4323511 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-08
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0085651
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.