کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
26654 | 43969 | 2013 | 7 صفحه PDF | دانلود رایگان |
In cyanine dye, new photoreaction paths involving multiphoton processes were uncovered by ultrafast transient absorption spectroscopy. In contrast to the conventional reaction path that proceeded through one-photon resonance to the S1 state by near-infrared light irradiation, the new reaction paths were found to proceed through near-infrared multiphoton excitation to higher excited states and the optical order of the electronic excitation was dependent on the type of photoproduct: a four-photon process for cis isomers and three for photodegradation. Leuco forms with saturated hydrocarbon chain seem to be formed by photodegradation. The ultraviolet pump fluence dependence of the cis isomer production was consistent with the near-infrared pump fluence dependence. Changing the near-infrared pump fluence controlled the number ratio of cis isomers to degraded molecules.
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► Ultrafast transient absorption spectroscopy.
► Photoisomerization of ICG molecule was completed within 2 ns.
► New photoisomerization path involving near-infrared four-photon process.
► New reaction path to leuco-forms involving near-infrared three-photon process.
► Control of the number ratio of cis-isomers to leuco-forms by changing pump fluence.
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 252, 15 January 2013, Pages 152–158