Two-Laser Flash Photolysis
FULL PAPER
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Experimental Section
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Materials: a- and b-Naphthoyl phenyl esters (aNpCO-OPh and bNpCO-
OPh) and a- and b-naphthoyl methyl esters (aNpCO-OMe and bNpCO-
OMe) were synthesized by reactions of naphtholyl chloride with phenol
and methanol, respectively. Benzoyl a- and b-naphthyl esters (PhCO-
OaNp and PhCO-ObNp) and acetyl a- and b-naphthyl esters (MeCO-
OaNp and MeCO-ObNp) were synthesized by reaction of a- and b-naph-
thol with benzoic anhydride and acetic anhydride, respectively. Benzo-
phenone from Nacalai Tesque Inc was purified from ethanol before use
as the triplet sensitizer. Acetonitrile (spectral grade) from Nacalai
Tesque Inc was used as received. All sample solutions were freshly pre-
pared and deoxygenated by bubbling with argon before irradiation. The
ground-state absorbance of the naphthyl derivatives was adjusted to be
1.0 at 266 nm during the 266 nm laser flash photolysis. BP(6.010 ꢀ3 m)
and naphthyl derivatives (6.010ꢀ3 m) were used during the two-color
two-laser flash photolysis. All experiments were carried out at room tem-
perature.
Two-color two-laser flash photolysis: Third and fourth harmonics (355
and 266 nm, respectively) from a Nd/YAG laser (Brilliant, Quantel; 5 ns
full width at half maximum (fwhm)) and the laser light at 425 nm
(7 mJpulseꢀ1) from an OPO laser (Continuum, Surelite OPO) which was
pumped by another Nd:YAG laser (Continuum, Surelite II-10; 5 ns
fwhm) were used as excitation light sources. Two laser flashes were
synchronized by a pulse generator with a delay time of 10 ns–10 ms. The
probe light was obtained from a 450 W Xe lamp (Osram XBO-450). The
transmitted probe light was focused on a monochromator (Nikon G250).
The output of the monochromator was monitored using a photomultiplier
tube (PMT, Hamamatsu Photonics, R928). The signal from the PMT was
recorded on a transient digitizer (Tektronix TDS 580D). A multichannel
analyzer system (Hamamatsu Photonics, C5967) was used for the mea-
surement of the transient absorption spectra. The total system was con-
trolled with a personal computer via GP-IB interface. To avoid any
damage of the sample solution by the probe light, a suitable cutoff filter
was used in front of the sample. The eight time shots to one sample at
each wavelength were carried out to get one set of experimental data,
and then the sample was replaced by the fresh one. The experiments
were carried out three times.
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Acknowledgements
This work has been partly supported by a Grant-in-Aid for Scientific Re-
search (Project 17105005, Priority Area (417), 21 st Century COE Re-
search, and others) from the Ministry of Education, Culture, Sports, Sci-
ence and Technology (MEXT) of Japanese Government. The authors
also thank to JSPS for a fellowship for X.C.
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Received: June 12, 2006
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Published online: January 10, 2007
Chem. Eur. J. 2007, 13, 3143 – 3149
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3149