Temperature-dependent rate constants for the reactions of gas-phase lanthanides with O{sub 2}
The reactivity of the gas-phase lanthanide atoms Ln (Ln = La-Yb with the exception of Pm) with O{sub 2} is reported. Lanthanide atoms were produced by the photodissociation of [Ln(TMHD){sub 3}] and detected by laser-induced fluorescence. For all the lanthanides studied with the exception of Yb, the reaction mechanism is bimolecular abstraction of an oxygen atom. The bimolecular rate constants (in molecule{sup {minus}1} cm{sup 3} s{sup {minus}1}) are described in Arrhenius form by {kappa}[De({sup 1}G{sub 4})] = (3.0 {+-} 0.4) x 10{sup {minus}10} exp ({minus}3.4 {+-} 1.3 kJ mol{sup {minus}1}/RT); Pr({sup 4}I{sub 9/2}), (3.1 {+-} 0.7) x 10{sup {minus}10} exp({minus}5.3 {+-} 1.5 kJ mol{sup {minus}1}/RT)/ Nd({sup 5}I{sub 4}), (3.6 {+-} 0.3) x 10{sup {minus}10} exp({minus}6.2 {+-} 0.4 kJ mol{sup {minus}1}/RT); Sm({sup 7}F{sub 0}), (2.4 {+-} 0.4) x 10{sup {minus}10} exp({minus}6.2 {+-} 1.5 kJ mol{sup {minus}1}/RT); Eu({sup 8}S{sub 7/2}), (1.7 {+-} 0.3) x 10{sup {minus}10} exp({minus}9.6 {+-} 0.7 kJ mol{sup {minus}1}/RT); Gd({sup 9}D{sub 2}), (2.7 {+-} 0.3) x 10{sup {minus}10} exp({minus}5.2 {+-} 0.8 kJ mol{sup {minus}1}/RT); Tb({sup 6}H{sub 15/2}), (3.5 {+-} 0.6) x 10{sup {minus}10} exp({minus}7.2 {+-} 0.8 kJ mol{sup {minus}1}/RT); Dy({sup 5}I{sub 8}), (2.8 {+-} 0.6) x 10{sup {minus}10} exp({minus}9.1 {+-} 0.9 kJ mol{sup {minus}1}/RT); Ho({sup 4}I{sub 15/2}), (2.4 {+-} 0.4) x 10{sup {minus}10} exp({minus}9.4 {+-} 0.8 kJ mol{sup {minus}1}/RT); Er({sup 3}H{sub 6}), (3.0 {+-} 0.8) x 10{sup {minus}10} exp({minus}10.6 {+-} 1.1 kJ mol{sup {minus}1}/RT); Tm({sup 2}F{sub 7/2}), (2.9 {+-} 0.2) x 10{sup {minus}10} exp({minus}11.1 {+-} 0.4 kJ mol{sup {minus}1}/RT),where the uncertainties represent {+-}2{sigma}. The reaction barriers are found to correlate to the energy required to promote an electron out of the 6s subshell. The reaction of Yb({sup 1}S{sub 0}) with O{sub 2} reacts through a termolecular mechanism. The limiting low-pressure third-order rate constants are described in Arrhenius form by {kappa}{sub 0}[Yb({sup 1}S{sub 0})] = (2.0 {+-} 1.3) x 10{sup {minus}28} exp({minus}9.5 {+-} 2.8 kJ mol{sup {minus}1}/RT) molecule{sup {minus}2} cm{sub 6} s{sup {minus}1}.
- Research Organization:
- Naval Academy, Annapolis, MD (US)
- OSTI ID:
- 20000054
- Journal Information:
- Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Vol. 103, Issue 36; Other Information: PBD: 9 Sep 1999; ISSN 1089-5639
- Country of Publication:
- United States
- Language:
- English
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