Two-photon absorption cross section determination for fluorene derivatives: analysis of the methodology and elucidation of the origin of the absorption processes.
A comprehensive analysis of the well-known open aperture Z-scan method, using a modified equation for the change in transmittance, is presented and accounts for discrepancies in two-photon absorption (2PA) cross sections between picosecond and femtosecond excitation. This new approach takes into account excited-state absorption and stimulated emission of the molecules studied. The two-photon absorption cross-section spectra of a series of six fluorene-based derivatives, determined using picosecond pulses, over a broad spectral range (500-900 nm), and this approach using a modified fitting procedure in the open aperture Z-scan is reported. We demonstrate that the fluorene derivatives exhibit two-photon absorption cross-section values between 700 and 5000 GM, when excited into the two-photon allowed electronic state. Excitation anisotropy spectra, measured to investigate the nature of the observed linear and nonlinear absorption bands, are presented and provide insight into the 2PA process.
Belfield
Kevin D
KD
Department of Chemistry and CREOL, College of Optics and Photonics, University of Central Florida, PO Box 162366, Orlando, Florida 32816-2366, USA. belfield@mail.ucf.edu
Bondar
Mykhailo V
MV
Hernandez
Florencio E
FE
Przhonska
Olga V
OV
Yao
Sheng
S
D016880:Anisotropy; D005449:Fluorenes / Q000737:chemistry*; D015394:Molecular Structure; D017785:Photons; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
D005449:Fluorenes