Determination and analysis of multiphoton excitation emissive species.: I,: Emission of PAHS in acidic medium,: II,: Multiphoton emission of possible PDT agents

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The exploitation of ultrafast laser properties has been recently increasing. Recent research in this lab demonstrated the ability of femtosecond pulses to give two photons simultaneously, exciting the system above the first excited state. This ability enables for extended environments of excitation, the study of molecular symmetries and photochemistry otherwise unobservable at single photon absorbencies. This paper highlights two uses of the laser system, the first being determination of the spectral properties of species being synthesized and 'tuned' to be able to have a strong two photon cross section. The second use is the excitation of highly symmetrical species displaying anomalous fluorescence emission.The trends of the properties of the novel substituted enediynes gives a greater insight to the properties that enable a large two-photon cross section, and enables us to postulate species that would be ideal for a C1-C5 cyclization process to be activated by the ultrafast laser pulse. Being able to observe the polycyclic aromatic hydrocarbons in acidic environments we are able to detect and identify multiple emissive and non-emissive species.