Temperature dependent rate constants for the reactions of gas phase lanthanides with N2O

The reactivity of gas phase lanthanide (Ln) atoms (Ln=La-Yb with the except ion of Pm) with N2O from 298 to 623 K is reported. Lanthanide atoms were pr oduced by the photodissociation of Ln(TMHD)(3) (TMHD=2,2,6,6-tetramethyl-3, 5-heptanato ion) and detected by laser-induced fluorescence. Large variatio ns in the reaction rate constants are observed. The bimolecular rate consta nts are described in Arrhenius form by k[Ce((1)G(4))]=(1.9+/-0.5) x 10(-10) exp(-0.8+/-0.8 kJ mol(-1)/RT); Pr(I-4(9/2)), (3.6+/-1.2) x 10(-10) exp(-8. 0+/-1.2 kJ mol(-1)/RT); Nd(I-5(4)), (3.4+/-0.4) x 10(-10) exp(-8.8+/-0.5 kJ mol(-1)/RT); Sm(F-7(0)), (3.2+/-1.1) x 10(-10) exp(-11.2+/-1.2 kJ mol(-1)/ RT); Eu(S-8(7/2)), (2.7+/-0.4)+/-10(-10) exp(-12.7+/-0.5 kJ mol(-1)/RT); Gd (D-9(2)), (2.0+/-0.3) x 10(-10) exp(-6.4+/-0.5 kJ mol(-1)/RT); Tb(H-6(15/2) ), (2.9+/-0.5) x 10(-10) exp(-10.9+/-0.6 kJ mol(-1)/RT); Dy(I-5(8)), (3.4+/ -0.8) x 10(-10) exp(-16.2+/-0.8 kJ mol(-1)/RT); Ho(I-4(15/2)), (2.9+/-0.5) x 10(-10) exp(-17.1+/-0.6 kJ mol(-1)/RT); Er(H-3(6)), (3.3+/-1.2) x 10(-10) exp(-18.4+/-1.2 kJ mol(-1)/RT); Tm(F-2(7/2)), (3.5+/-0.6) x 10(-10) exp(-1 9.5+/-0.6 kJ mol(-1)/RT); Yb(S-1(0)), (2.5+/-0.2) x 10(-10) exp(-20.2+/-0.3 kJ mol(-1)/RT) where the uncertainties represent +/-2 sigma. The reaction barriers are found to correlate to the energy required to promote an electr on out of the 6s subshell. (C) 1999 American Institute of Physics. [S0021-9 606(99)00626-1].