Two-photon cross-sections of the photosensitizers m-THPC and m-THPP in the 1.05–1.45μm range

The two-photon absorption of the photosensitizers 5,10,15,20-tetrakis( m -hydroxyphenyl) porphyrin and the corresponding chlorin has been studied in the near infrared (IR) range using open-aperture z -scan technique. We found cross sections of 10–40 GM in the Q-band region, comparable to values in the Soret-band. Both photosensitizers are promising candidates for IR two-photon photodynamic therapy given the better penetration of IR light into tissue.