Multi Photon Absorption Processes Induced by Ultra-Fast Light Pulses

Here we present a comparative investigation of the two-photon excitation of six photosensitizers of the porphyrin type: 5,10,15,20-tetrakis (m-hydroxyphenyl) porphyrin (m-THPP), chlorin 5,10,15,20-tetrakis (m-hydroxyphenyl) chlorin (m-THPC, Foscan, temoporfin), palladium 5,10,15,20-tetrakis (3-hydroxyphenyl)-porphyrinato-palladium-(II) (m-THPP-PD), 5,15-Bis-(4-carboxphenyl)-10,20-dihexyl-porphyrin (m-TCP-PD), Al(tpfc)py1 and Al(tpfc)py2 type 5,10,15 tris (pentafluorophenyl) corrole in the spectral range of 1.04¿1.45 ¿m.We also paid attention to the polarization effect. We measured the two-photon absorption cross-sections for linear and circular polarized exciting pulses. The polarization effects can reveal important information about photophysical properties of the organic compounds. It can provide information about the angle between dipole moments, symmetry of excited states.