Future prospect - selectivity in the desorption

Reaction selectivity is observed on laser-induced desorption and dissociation of NO and CO chemisorbed on Ni, Pd, and Pt surfaces via the electronic transition using visible and ultraviolet nanosecond-pulsed lasers, as listed in Table 6. The open circle shows that desorption and dissociation have been observed, while the cross mark means that they have not been observed. These metals are isoelectronic and the band structure is very similar, but the activity on laser-induced desorption and dissociation is remarkably different. The origin of the different desorption activity between Pt and other transition metals of Ni and Pd may be closely related with the nature of the antibonding 2-ira state in adsorbed NO and CO [11]. 

The bandwidth of the d band is considered as one of the candidates for the origin for the desorption activity [11]. The bandwidth of the Pt d band ( 8 eV) is wider than those of Ni and Pd ( 5 eV). If the bandwidth is wider than 8 eV, the 5a state of NO or the bonding 5ab state of CO is resonant with the d state of the substrate metal. The strong resonant 5a-d interaction causes attenuation of the 2-Tr-d interaction [84]. Therefore, it is considered that excitation to the 2-ira state brings longer lifetime of the 

the band width is represented by W = 2V3z (3, and W is proportional to Jz. 

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