New conjugated oligomers were synthesized by reacting diphenylacetylene under high pressure of 0.13-0.76 GPa at 250 and 300ะC for 1-10 h. The numberaverage molecular weight M V n , and the weight-average molecular weight M V w increased with pressure, but those values were independent of temperature
Optical-limiting property of cyclic phenylacetylene oligomer synthesized under high pressure
โ Scribed by Yoshitsugu Kojima; Takaaki Matsuoka; Hideroh Takahashi
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 425 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0887-6266
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โฆ Synopsis
The optical-limiting property of a new cyclic phenylacetylene oligomer was investigated. Toluene solutions of the oligomer contained within a quartz cell were irradiated with the pulse from frequency doubled Nd : Yag laser a t 532 nm. At low input fluence, the transmittance of the toluene solution was constant and agreed well with that obtained by spectrophotometer. At high input fluence, the transmittance of the solution above a concentration of 5 wt % decreased with input fluence. The oligomer had a n optical limiting property. As the concentration of the oligomer increased from 5 to 20 wt %, the threshold for optical limiting decreased. T h e threshold was independent of the molecular weight. The optical limiting property was analyzed by the following equation obtained according to the reverse saturable absorption mechanism; log(Zo/Z) = K(Zo -I ) + A,, where Zo is the input fluence, Z is the output fluence, K is a parameter depending on the absorption cross section and the relaxation time, and A, is the absorbance of the ground state. 0 1996 John Wiley & Sons, Inc.
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