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A study of the BrO and BrO2 radicals with vacuum ultraviolet photoelectron spectroscopy

A study of the BrO and BrO2 radicals with vacuum ultraviolet photoelectron spectroscopy
A study of the BrO and BrO2 radicals with vacuum ultraviolet photoelectron spectroscopy
The BrO radical, prepared by the Br+O-3 reaction, has been investigated by ultraviolet photoelectron spectroscopy. Two vibrationally resolved bands were observed corresponding to the ionizations BrO+(X (3)Sigma(-))<-- BrO(X (2)Pi) and BrO+(a (1)Delta)<-- BrO(X (2)Pi). These assignments are supported by the results of complete active space self-consistent field/multireference configuration interaction (CASSCF/MRCI) calculations performed as part of this work. The adiabatic ionization energies of these bands were measured as (10.46 +/- 0.02) and (11.21 +/- 0.02)eV, respectively. Measurement of the vibrational separations in these bands led to estimates of the vibrational constants in the ionic states of (840 +/- 30) cm(-1) and (880 +/- 30) cm(-1), and Franck-Condon simulations of the vibrational envelopes gave values of the ionic state bond lengths of (1.635 +/- 0.005) and (1.641 +/- 0.005) Angstrom for the X (3)Sigma(-) and a (1)Delta states of BrO+, respectively. The O+Br-2 reaction was found to give a band at (10.26 +/- 0.02) eV associated with a reaction product. Comparison of the results obtained for the Br+O-3 reaction showed that it could not be assigned to ionization of BrO. Calculations of the first adiabatic ionization energies and Franck-Condon simulations of the vibrational envelopes of the first photoelectron bands of BrO2 and Br2O and their isomers demonstrated that this band corresponds to the first ionization of OBrO, the BrO2+(X (1)A(1))<-- BrO2(X B-2(1)) ionization. Franck-Condon simulations were performed with the experimental geometry of BrO2(X B-2(1)) but with different cationic state geometries. The simulated envelope which most closely matched the experimental envelope gave geometrical parameters of r(e)=1.6135 Angstrom and angle OBrO=117.5 degrees for the ionic state.
effective core potentials, ab-initio, rotational spectrum, electronic states, molecular-properties, dibromine monoxide, ionization-energy, gaussian-2 theory, bromine dioxide, halogen oxides
0021-9606
6262-6274
Dyke, J. M.
42960400-b7de-4c53-810c-76a758fc3ac5
Gamblin, S. D.
e2dd394a-3999-4a4c-99ec-d351ac0243cf
Hooper, N.
ea5d763b-aea5-4deb-919c-e810f3dca647
Lee, E. P. F.
444375ff-0e52-40cc-a95a-dcaec2415236
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Mok, D. K. W.
20a1d918-4bdb-49c3-844c-94404f99239b
Chau, F. T.
53ebc8f8-5e82-4b34-9795-45f0cb63c4ac
Dyke, J. M.
42960400-b7de-4c53-810c-76a758fc3ac5
Gamblin, S. D.
e2dd394a-3999-4a4c-99ec-d351ac0243cf
Hooper, N.
ea5d763b-aea5-4deb-919c-e810f3dca647
Lee, E. P. F.
444375ff-0e52-40cc-a95a-dcaec2415236
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Mok, D. K. W.
20a1d918-4bdb-49c3-844c-94404f99239b
Chau, F. T.
53ebc8f8-5e82-4b34-9795-45f0cb63c4ac

Dyke, J. M., Gamblin, S. D., Hooper, N., Lee, E. P. F., Morris, A., Mok, D. K. W. and Chau, F. T. (2000) A study of the BrO and BrO2 radicals with vacuum ultraviolet photoelectron spectroscopy. The Journal of Chemical Physics, 112 (14), 6262-6274. (doi:10.1063/1.481271).

Record type: Article

Abstract

The BrO radical, prepared by the Br+O-3 reaction, has been investigated by ultraviolet photoelectron spectroscopy. Two vibrationally resolved bands were observed corresponding to the ionizations BrO+(X (3)Sigma(-))<-- BrO(X (2)Pi) and BrO+(a (1)Delta)<-- BrO(X (2)Pi). These assignments are supported by the results of complete active space self-consistent field/multireference configuration interaction (CASSCF/MRCI) calculations performed as part of this work. The adiabatic ionization energies of these bands were measured as (10.46 +/- 0.02) and (11.21 +/- 0.02)eV, respectively. Measurement of the vibrational separations in these bands led to estimates of the vibrational constants in the ionic states of (840 +/- 30) cm(-1) and (880 +/- 30) cm(-1), and Franck-Condon simulations of the vibrational envelopes gave values of the ionic state bond lengths of (1.635 +/- 0.005) and (1.641 +/- 0.005) Angstrom for the X (3)Sigma(-) and a (1)Delta states of BrO+, respectively. The O+Br-2 reaction was found to give a band at (10.26 +/- 0.02) eV associated with a reaction product. Comparison of the results obtained for the Br+O-3 reaction showed that it could not be assigned to ionization of BrO. Calculations of the first adiabatic ionization energies and Franck-Condon simulations of the vibrational envelopes of the first photoelectron bands of BrO2 and Br2O and their isomers demonstrated that this band corresponds to the first ionization of OBrO, the BrO2+(X (1)A(1))<-- BrO2(X B-2(1)) ionization. Franck-Condon simulations were performed with the experimental geometry of BrO2(X B-2(1)) but with different cationic state geometries. The simulated envelope which most closely matched the experimental envelope gave geometrical parameters of r(e)=1.6135 Angstrom and angle OBrO=117.5 degrees for the ionic state.

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Published date: 8 April 2000
Keywords: effective core potentials, ab-initio, rotational spectrum, electronic states, molecular-properties, dibromine monoxide, ionization-energy, gaussian-2 theory, bromine dioxide, halogen oxides

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Local EPrints ID: 18897
URI: http://eprints.soton.ac.uk/id/eprint/18897
ISSN: 0021-9606
PURE UUID: dfd95ef7-b977-4273-917e-374105c7edd8

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Date deposited: 21 Dec 2005
Last modified: 15 Mar 2024 06:08

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Contributors

Author: J. M. Dyke
Author: S. D. Gamblin
Author: N. Hooper
Author: E. P. F. Lee
Author: A. Morris
Author: D. K. W. Mok
Author: F. T. Chau

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