We report here on the linear and non linear optical response of some batches of the polydiacetylene poly-3BCMU with molecular weight ranging from some ten thousands to several hundred thousands. Thin films were formed by spin coating from chloroform solutions. The refractive index of the films was evaluated by m-line spectroscopy, the visible absorption spectra were recorded and the two-photon absorption spectrum was measured in the range 800-1400 nm by using femtosecond pulses at 1kHz repetion rate. the two- photon absorption coefficient was two times larger in the case of films made from polymers with higher molecular weight. The refractive index also varied by 5x10-2 at 840 nm, with larger values and increased birefringence pertaining to films made from high molecular weight polymers. The results of our experiment suggest that in poly-3BCMU films with high molecular weight a more ordered planar arrangement of the polymer chains is promoted.
Molecular Weight Induced Order in Poly-3BCMU Spun Films
GRANDO, DANIELA;BANFI, GIAN PIERO;
2003-01-01
Abstract
We report here on the linear and non linear optical response of some batches of the polydiacetylene poly-3BCMU with molecular weight ranging from some ten thousands to several hundred thousands. Thin films were formed by spin coating from chloroform solutions. The refractive index of the films was evaluated by m-line spectroscopy, the visible absorption spectra were recorded and the two-photon absorption spectrum was measured in the range 800-1400 nm by using femtosecond pulses at 1kHz repetion rate. the two- photon absorption coefficient was two times larger in the case of films made from polymers with higher molecular weight. The refractive index also varied by 5x10-2 at 840 nm, with larger values and increased birefringence pertaining to films made from high molecular weight polymers. The results of our experiment suggest that in poly-3BCMU films with high molecular weight a more ordered planar arrangement of the polymer chains is promoted.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
