Photoionization of iodine atoms: Angular distributions and relative partial photoionization cross-sections in the energy region 11.0-23.0 eV

Journal Article · Sat Aug 28 04:00:00 EDT 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3469798· OSTI ID:21559906

Eypper, Marie; Innocenti, Fabrizio; Morris, Alan; Dyke, John M ^[1]; Stranges, Stefano ^[2]; West, John B ^[3]; King, George C ^[4]

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1. School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)
2. Department of Chemistry, University La Sapienza, Rome, Italy and IOM CNR, TASC Laboratory, Basovizza, Trieste 34012 (Italy)
3. STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom)
4. School of Physics and Astronomy, Manchester University, Manchester M13 9PL (United Kingdom)

Relative partial photoionization cross-sections and angular distribution parameters, {beta}, have been measured for the first, I{sup +}({sup 3}P{sub 2})<-I({sup 2}P{sub 3/2}), and fourth, I{sup +}({sup 1}D{sub 2})<-I({sup 2}P{sub 3/2}), (5p){sup -1} photoelectron (PE) bands of atomic iodine, by performing angle-resolved constant-ionic-state (CIS) measurements on these PE bands in the photon energy range 11.0-23.0 eV. Three Rydberg series, two ns and one nd series, which converge to the I{sup +} {sup 3}P{sub 1} limit at 11.33 eV and four Rydberg series, two ns and two nd series, which converge to the I{sup +} {sup 1}D{sub 2} limit at 12.15 eV were observed in the first PE band CIS spectra. The fourth band CIS spectrum showed structure in the 12.9-14.1eV photon energy range, which is also seen in the first band CIS spectra. This structure arises from excitation to ns and nd Rydberg states that are parts of series converging to the I{sup +} {sup 1}S{sub 0} limit we reported on earlier, as well as 5s{yields}5p excitations in the photon energy range 17.5-22.5 eV. These atomic iodine CIS spectra show reasonably good agreement with the equivalent spectra obtained for atomic bromine. The {beta}-plots for the first PE band recorded up to the I{sup +} {sup 3}P{sub 1} and I{sup +} {sup 1}D{sub 2} limits only show resonances corresponding to some of the 5p{yields}nd excitations observed in the first band CIS spectra scanned to the I{sup +} {sup 1}D{sub 2} limit (12.15 eV). These plots are interpreted in terms of an angular momentum transfer model with the positive values of {beta} obtained on resonances corresponding to parity allowed j{sub t}=1 and 3 channels and the off-resonance negative {beta} values corresponding to parity unfavored channels, where j{sub t} is the quantum number for angular momentum transfer between the molecule, and the ion and photoelectron. The {beta}-plots recorded for iodine are significantly different from those obtained for atomic bromine. Comparison of the experimental CIS spectra and {beta}-plots with available theoretical results highlights the need for higher level calculations which include factors such as configuration interaction in the initial and final states, relativistic effects including spin-orbit interaction, and autoionization via resonant Rydberg states.

• OSTI ID: 21559906
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 8 Vol. 133; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
ANGULAR MOMENTUM TRANSFER
ATOM COLLISIONS
ATOMS
AUTOIONIZATION
BOSONS
BROMINE
CHARGED PARTICLES
COLLISIONS
CONFIGURATION INTERACTION
COUPLING
CROSS SECTIONS
DISTRIBUTION
ELECTRON SPECTROSCOPY
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EXCITATION
EXCITED STATES
HALOGENS
INTERMEDIATE COUPLING
IODINE IONS
IONIZATION
IONS
L-S COUPLING
MASSLESS PARTICLES
MOMENTUM TRANSFER
NONMETALS
PARITY
PARTICLE PROPERTIES
PHOTOELECTRON SPECTROSCOPY
PHOTOIONIZATION
PHOTON COLLISIONS
PHOTON-ATOM COLLISIONS
PHOTONS
RELATIVISTIC RANGE
RESONANCE
RYDBERG STATES
SPECTROSCOPY