TY - JOUR
T1 - Excited-states and lightfastness of linear trans-quinacridone pigment nanoparticles
AU - Miyashita, Yousuke
AU - Yokoyama, Hiroshi
AU - Tanabe, Mamoru
AU - Kasai, Hitoshi
AU - Nakanishi, Hachiro
AU - Miyashita, Tokuji
N1 - Funding Information:
This work is financially supported by New Energy and Industrial Development Organization, Japan. The authors wish to thank Mr. Shinichi Horino and Ms. Keiko Mesaki for their assistance in performing various experiments, and to express our sincere gratitude to Professor Hidetoshi Oikawa and many students of Oikawa Laboratory for preparation of nanoparticles by reprecipitation method.
PY - 2009/1/25
Y1 - 2009/1/25
N2 - The photoexcited state of linear trans-quinacridone pigment nanoparticles, prepared by a reprecipitation method, was analyzed by time-resolved spectroscopy. The analysis showed that the S1 state of the linear trans-quinacridone nanoparticles undergoes a quantitative, non-radiative relaxation to the ground state with a time constant of about 100 ps. By contrast, the S1 state of the molecular dispersion state (dilute solution state) was relatively long-lived (21 ns). This, together with the intersystem crossing to T1 observed in the molecular dispersion state, clearly distinguished the nanoparticles from the molecular dispersion state. By comparing the two in terms of lightfastness, the nanoparticles were found to be much more lightfast than the molecular dispersion state. It was speculated that the superior lightfastness of the linear trans-quinacridone pigment nanoparticles was not due to the molecular structure but the facilitated S1 relaxation by the aggregation of the molecules.
AB - The photoexcited state of linear trans-quinacridone pigment nanoparticles, prepared by a reprecipitation method, was analyzed by time-resolved spectroscopy. The analysis showed that the S1 state of the linear trans-quinacridone nanoparticles undergoes a quantitative, non-radiative relaxation to the ground state with a time constant of about 100 ps. By contrast, the S1 state of the molecular dispersion state (dilute solution state) was relatively long-lived (21 ns). This, together with the intersystem crossing to T1 observed in the molecular dispersion state, clearly distinguished the nanoparticles from the molecular dispersion state. By comparing the two in terms of lightfastness, the nanoparticles were found to be much more lightfast than the molecular dispersion state. It was speculated that the superior lightfastness of the linear trans-quinacridone pigment nanoparticles was not due to the molecular structure but the facilitated S1 relaxation by the aggregation of the molecules.
KW - Lightfastness
KW - Linear trans-quinacridone
KW - Organic nanoparticle
KW - Reprecipitation method
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U2 - 10.1016/j.jphotochem.2008.10.024
DO - 10.1016/j.jphotochem.2008.10.024
M3 - Article
AN - SCOPUS:58049191293
VL - 201
SP - 208
EP - 213
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
SN - 1010-6030
IS - 2-3
ER -