Solute migration caused by excited state absorptions
Using the Z -scan technique, we find that migration of chloroaluminum phthalocyanine in liquid ethanol can be induced by the absorption of a 19 ps laser pulse with energy exceeding a threshold but not by that of a 2.8 ns pulse depositing more energy at the solute molecules. Considering each solute m...
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Veröffentlicht in: | The Journal of chemical physics 2009-01, Vol.130 (2), p.024511-024511-10 |
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Hauptverfasser: | , , , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Using the
Z
-scan technique, we find that migration of chloroaluminum phthalocyanine in liquid ethanol can be induced by the absorption of a
19
ps
laser pulse with energy exceeding a threshold but not by that of a
2.8
ns
pulse depositing more energy at the solute molecules. Considering each solute molecule as an oscillator confined within a potential well, we explain, in accordance with the five-energy-band model, that solute molecules excited by a
19
ps
pulse retain more translational excess energy to overcome the potential well barrier compared with those excited by a
2.8
ns
pulse of equal energy. Therefore, they are more likely to migrate out of the laser beam center, weakening the solution's absorption that we detect in the
Z
-scan measurements. Furthermore, we theoretically infer that the
19
ps
pulse-induced solute migration tends to be nonquasistatic and experimentally verify that it cannot be attributed to the Soret effect, a quasistatic process. |
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ISSN: | 0021-9606 1089-7690 |
DOI: | 10.1063/1.3033563 |