Degenerate multi-photon properties of spirofluorene derivatives.
Two- and three-photon absorption properties of the fluorene-based chromophores have been investigated. The two- and three-photon absorption cross-section are found to be increased with the strength of the electron donor groups in the order of N-ethylcarbazoyl (1), triphenylamino (2), and N,N-dibutylanilino (3) groups. This nonlinear absorption enhancement can be interpreted by the increase of intramolecular charge transfer facilitated by strong electron donors and the decreased detuning energy (deltaE). Furthermore, direct laser microfabrication by two-photon photopolymerization with compound 2 as a two-photon sensitizer was carried out. Laser exposure time-dependent lateral voxel size has also been studied.
Department of Advanced Materials, Hannam University, Daejeon 305-811, Korea.
Namchul
N
Cho
Patrice L
PL
Baldeck
Guang S
GS
He
Do-Hoon
DH
Hwang
Paras N
PN
Prasad
Prém
P
Prabhakaran
Tae-Dong
TD
Kim
Kwang-Sup
KS
Lee