Nanosecond transient
absorption measurements were done on an Applied
Photophysics LKS 60 Laser Flash Photolysis system with laser excitation
from a Quantel Brilliant B Q-switched laser with second and third
harmonic attachments and an OPO (OPOTEK) for visible light generation,
and data recorded using an Agilent Infinium digitizer. Laser excitation
of the sample was typically supplied at 450 nm, with a power output
of 12 mJ/pulse. Spectra were typically corrected for emission by adding
the absolute value of an emission decay signal (calculated as a transient
absorbance signal) to the observed transient absorption signal at
the same wavelength. Unfortunately, this resulted often in an overcompensation
that led to observation of a net absorption signal, especially at
wavelengths where the intensity of the amplified white light source
of the TA was weak (>650 nm). Observed maxima in the red varied
depending
on the degree of overcompensation. To maintain constant ionic strength
in quenching experiments, tetrabutylammonium hexafluorophosphate was
added to all samples studied by transient absorption.
absorption measurements were done on an Applied
Photophysics LKS 60 Laser Flash Photolysis system with laser excitation
from a Quantel Brilliant B Q-switched laser with second and third
harmonic attachments and an OPO (OPOTEK) for visible light generation,
and data recorded using an Agilent Infinium digitizer. Laser excitation
of the sample was typically supplied at 450 nm, with a power output
of 12 mJ/pulse. Spectra were typically corrected for emission by adding
the absolute value of an emission decay signal (calculated as a transient
absorbance signal) to the observed transient absorption signal at
the same wavelength. Unfortunately, this resulted often in an overcompensation
that led to observation of a net absorption signal, especially at
wavelengths where the intensity of the amplified white light source
of the TA was weak (>650 nm). Observed maxima in the red varied
depending
on the degree of overcompensation. To maintain constant ionic strength
in quenching experiments, tetrabutylammonium hexafluorophosphate was
added to all samples studied by transient absorption.
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