NO desorption of on-top species from Pt

The rotational energy distribution of desorbed NO from on-top species on Pt(l 1 1) at A. = 192 nm is observed to have a non-Boltzmann form, as shown in Fig. 14. Furthermore, the population in the two spin-orbit states is substantially inverted, since the population ratio of 2 = 1/2 and 3/2 is 1 2.2 in low J region. For desorption of hep hollow species at = 193 nm, on the other hand, the population ratio 

In order to estimate the tilt angle in the ground state from Er0, the InN(J) vs. /E curve is replotted from Fig. 14 for 2 = 1/2, as shown in Fig. 22. With the exception of several points in the higher Et 

The inversion population of the two spin-orbit states is also caused by the tilt geometry in the initial state. The principal axis of the NO 2tt orbital adsorbed in the tilt geometry is not parallel to the molecular axis due to a strong chemical interaction between the 2rr and the Pt 5d orbital. The population between the spin-orbit states of 12 = 1/2 and 3/2 is relevant to the ratio of these state densities in addition to the Boltzmann factor due to the energy difference. If the principal axis of the electronic configuration is not parallel to the molecular axis, the orbital angular momentum of the adsorbed molecule does not take a good quantum and the relation of the state density is broken. However, this simple consideration cannot interpret the experimental results. 

---