Multiphoton Excitation for organic complex - Essay Example

wo photon absorption active; but, it is not guaranteed that they will exhibit interesting and useful three photon absorption properties such as frequency up-converted lasing [10]. Based on this reason, our University Department of Chemistry Prof Ricky Wong Man Shing and his student Dr.Xin Jiang Feng have developed and synthesized a new set of organic complexes p-PhN-OF(n)-TAZ n = 2 to 6 from deep investigation and collection of fundamental information and applications such as multi-photon properties and multi-photon cavityless lasing etc.

The most important aspect is that it can let us explore and understand the more Physics behind the discovery. In this chapter, am going to analyse the use of p-PhN-OF(n)-TAZ series for a set of nonlinear optical experiments to verify the multi-photon properties. The p-PhN-OF(n)-TAZ series are type of D--A using oligofluorenes (OF) as a  conjugated core end capped in which D is the end capped with the electron – donating diphenylamino group and the unconventionally employed electron-deficient 1,2,4-triazole (TAZ) derivates as an acceptor designed and synthesized for multiphoton absorption investigation [10].

The electron was pushed from Donor (D) to pull side of Acceptor (A) in the - conjugation system which is called intramolecular charge transfer. In addition, the size of length of conjugation is related to enhance the cross section value of two-photon absorption and three-photon absorption [11]. Unless, the value of cross section is reach to saturation level. Under fig 4.1, the linear absorption spectra of the organic materials p-PhN-OF(n)-TAZ series (n = 2 ~ 6) was dissolved in Toluene solution, the series exhibits the two absorption peaks characteristics.

The weak absorption peak appears around 300-310 nm attributed to the n* transition of triarylamine moieties and the broad absorption band spanning from 378-415 nm corresponds to the * transition of fluorene-based -conjugated core. The