Abstract
Two methods based on vacuum ultraviolet (vuv) photoionization are presented for the determination of the spin-orbit branching fractions of the halogen atom produced in the photodissociation of halogenated hydrocarbons. Both methods make use of differences in the photoionization cross sections of the 2P3/2 ground state and the 2P1/2 excited-state of the neutral halogen atom. In the first approach, measurements of the total photoionization signal of the halogen atom are made at several vuv wavelengths, and the difference in the wavelength dependences for the 2P3/2 and 2P1/2 atoms allows the extraction of the branching fractions. In the second approach, the vuv wavelength is set close to the ionization threshold of the 2P 3/2 atom (well above that of the 2P1/2 atom), and measurements are made at several electric field strengths, which shift the ionization threshold and thus vary the photoionization cross sections. In both methods, the relative cross sections of the ground- and excited-state atoms are determined by using the known branching fractions for the 266 nm photodissociation of methyl iodide. These methods are applied to the photodissociation of isopropyl iodide and allyl iodide, two systems for which standard ion-imaging techniques do not provide unique branching fractions.
| Original language | English |
|---|---|
| Pages (from-to) | 3901-3906 |
| Number of pages | 6 |
| Journal | Journal of Physical Chemistry A |
| Volume | 111 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - May 17 2007 |
| Externally published | Yes |
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- Physical and Theoretical Chemistry
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Determination of spin-orbit branching fractions in the photodissociation of halogenated hydrocarbons. / Fan, H.; Pratt, S. T.
In: Journal of Physical Chemistry A, Vol. 111, No. 19, 17.05.2007, p. 3901-3906.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Determination of spin-orbit branching fractions in the photodissociation of halogenated hydrocarbons
AU - Fan, H.
AU - Pratt, S. T.
PY - 2007/5/17
Y1 - 2007/5/17
N2 - Two methods based on vacuum ultraviolet (vuv) photoionization are presented for the determination of the spin-orbit branching fractions of the halogen atom produced in the photodissociation of halogenated hydrocarbons. Both methods make use of differences in the photoionization cross sections of the 2P3/2 ground state and the 2P1/2 excited-state of the neutral halogen atom. In the first approach, measurements of the total photoionization signal of the halogen atom are made at several vuv wavelengths, and the difference in the wavelength dependences for the 2P3/2 and 2P1/2 atoms allows the extraction of the branching fractions. In the second approach, the vuv wavelength is set close to the ionization threshold of the 2P 3/2 atom (well above that of the 2P1/2 atom), and measurements are made at several electric field strengths, which shift the ionization threshold and thus vary the photoionization cross sections. In both methods, the relative cross sections of the ground- and excited-state atoms are determined by using the known branching fractions for the 266 nm photodissociation of methyl iodide. These methods are applied to the photodissociation of isopropyl iodide and allyl iodide, two systems for which standard ion-imaging techniques do not provide unique branching fractions.
AB - Two methods based on vacuum ultraviolet (vuv) photoionization are presented for the determination of the spin-orbit branching fractions of the halogen atom produced in the photodissociation of halogenated hydrocarbons. Both methods make use of differences in the photoionization cross sections of the 2P3/2 ground state and the 2P1/2 excited-state of the neutral halogen atom. In the first approach, measurements of the total photoionization signal of the halogen atom are made at several vuv wavelengths, and the difference in the wavelength dependences for the 2P3/2 and 2P1/2 atoms allows the extraction of the branching fractions. In the second approach, the vuv wavelength is set close to the ionization threshold of the 2P 3/2 atom (well above that of the 2P1/2 atom), and measurements are made at several electric field strengths, which shift the ionization threshold and thus vary the photoionization cross sections. In both methods, the relative cross sections of the ground- and excited-state atoms are determined by using the known branching fractions for the 266 nm photodissociation of methyl iodide. These methods are applied to the photodissociation of isopropyl iodide and allyl iodide, two systems for which standard ion-imaging techniques do not provide unique branching fractions.
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U2 - 10.1021/jp0670034
DO - 10.1021/jp0670034
M3 - Article
VL - 111
SP - 3901
EP - 3906
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 19
ER -