EVALUATION OF THE EXOTHERMICITY OF THE CHEMI-IONIZATION REACTION Sm + O _ SmO+ + e_

Heaven, Michael

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https://hdl.handle.net/2142/79216 Copy

Description

Title

EVALUATION OF THE EXOTHERMICITY OF THE CHEMI-IONIZATION REACTION Sm + O _ SmO+ + e_

Author(s)

Heaven, Michael

Contributor(s)

• Viggiano, Albert
• Shuman, Nicholas S.
• Ard, Shaun
• Melko, Joshua J.
• VanGundy, Robert A.
• Bartlett, Joshua
• Armentrout, Peter B.
• Kim, JungSoo
• Cox, Richard M

Issue Date

25-Jun-15

Keyword(s)

Metal containing

Abstract

The chemi-ionization reaction Sm + O $rightarrow$ SmO$^{+}$ + e$^{-}$ has been used for chemical release experiments in the thermosphere. This reaction was chosen, in part, because the best available data indicated that it is exothermic by 0.35 $pm$ 0.12 eV. Low ion yields in the initial atmospheric release experiments raised questions concerning the accuracy of the ionization energy (IE) for SmO and the bond dissociation energy (BDE) of SmO$^{+}$. New measurements of the BDE, obtained using a selected ion flow tube and guided ion beam techniques, yielded a more precise value of 5.73 $pm$ 0.07 eV. The ionization energy of SmO was reexamined using pulsed-field ionization zero kinetic energy (ZEKE) photoelectron spectroscopy. The value obtained, 5.7427 $pm$ 0.0006 eV, was significantly higher than the literature value. Combined with literature bond energies of SmO, this IE indicates an exothermicity for Sm + O $rightarrow$ SmO$^{+}$ + e$^{-}$ of 0.14 $pm$ 0.17 eV, independent from and in agreement with the value deduced from the guided ion beam measurements. The implications of these results for interpretation of chemical release experiments are considered.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79216

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