Reactions of carbon and germanium atoms in specific electronic states by resonance absorption spectroscopy in the time-domain

• Main Author: Ioannou, A. X.
• Published: University of Cambridge 1997
• Subjects: 541.39
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604941

A new body of absolute rate data is been reported for the collisional removal of ground state germanium atoms, Ge(4<SUP>3</SUP>P<SUB>j</SUB>) with 17 olefins and 10 acetylenes. The rate data derived from the present measurements have employed atomic monitoring of a group of spin-orbit components of the atom. This yields results which are significantly slower than those obtained from the measurements on individual spin-orbit components of germanium with some of the smaller organic reactants, in particular, for GE(4<SUP>3</SUP>P<SUB>j</SUB>). Kinetic data with other reactants, mainly simple molecules, have primarily indicated Boltzmann equilibrium during reaction from the equality of decay rates for the individual spin-orbit states in Ge(4<SUP>3</SUP>P<SUB>0,1,2</SUB>). These present results are in contrast to previous analogues measurements on C(<SUP>3</SUP>P<SUB>j</SUB>) and Si(<SUP>3</SUP>P<SUB>j</SUB>) where, for Si(<SUP>3</SUP>P<SUB>j</SUB>) in particular, rate data for the spin-orbit manifold overall was found to be consistent with those obtained for specific measurements on Si(<SUP>3</SUP>P<SUB>0,1,2</SUB>) and is discussed in further detail. The collisional quenching of electronically excited germanium atoms, Ge(41So), 2.029 eV above the ground state, has been investigated with 13 small molecules, employing time-resolved atomic resonance absorption spectroscopy in ultra-violet. In contrast to previous investigations using the "single-shot" mode at high energy, Ge(<SUP>1</SUP>S<SUB>0</SUB>) has been generated by the repetitive pulsed irradiation of Ge(CH<SUB>3</SUB>)<SUB>4</SUB> at low energy and using signal averaging techniques, which increases the signal-to-noise ratio. The current results are compared with previous data for Ge(1S<SUB>0</SUB>) derived in the "single-shot" mode where there is general agreement though with some exceptions which are discussed in the appropriate chapter of the thesis. Finally, a large new body of absolute rate data is reported for the collisional quenching of Ge(4<SUP>1</SUP>S<SUB>0</SUB>) in the presence of 16 alkenes and 9 alkynes. It is shown that the rate data are dominated by the polarisability of the colliding molecule within the context of the simplified model using a classical capture theory.