ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The ground and first excited states of the organic dyes quinizarin (Q) and tetrahydroxyphenylporphyrin (TOHP) chemisorbed on γ-Al2O3 were investigated with semiempirical PM3 and multireference CI methods. Q/γ-Al2O3 and TOHP/γ-Al2O3 represent promising materials for frequency domain optical data storage (FDOS) based on persistent spectral hole burning (PSHB), since it is possible to detect spectral holes at high temperatures (77 K). To find out whether differences in the electronic structure between the free and the adsorbed molecules account for the hole-burning properties, we performed calculations of Q–Al complexes with various coordination spheres. The calculated vertical excitation energies for the first electronically excited state of the investigated structures are in good agreement with experimental data. Analysis of the molecular orbitals shows that complexation of the investigated molecules with Al affects the electronic structure of the dyes only little. Furthermore, the character of the first excited state is conserved. The change of the dipole moment between the ground and the first excited states is about the same for the free and for the complexated systems. Therefore, it is concluded that hole burning of dye molecules chemisorbed on γ-Al2O3 at high temperatures is not due to a change of the electronic structure of the adsorbed dye molecules compared to the free dye molecules, but has to be attributed to the special interactions of Q with the γ-Al2O3 surface. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469635
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