Fast-gated intensified charge-coupled device camera to record time-resolved fluorescence spectra of tryptophan.
The possibilities of a 200 ps gated intensified charge-coupled device (CCD) camera to record time-resolved fluorescence were explored using the fluorescing amino acid tryptophan and its derivative Nacetyl-tryptophan amide (NATA) as model compounds. The results were compared to complementary data from time-correlated single-photon counting (TCSPC) experiments. If a spectral resolution of 1-2 nm is desired, the fast-gated intensified CCD (ICCD) camera is the method of choice. For a 10(-5) M tryptophan solution, time-resolved emission spectra and intensity decays (measured over 12 ns at 25 ps resolution) could be obtained in typically 10 minutes, giving the well-known lifetimes of 0.5 and 3 ns. In addition, a longer lifetime of 7 ns was found at the red edge of the spectrum. The very short gate time of the ICCD camera allowed us to observe a shift in the emission maximum of tryptophan even within the first nanosecond of decay of the fluorescence emission. As expected from the tryptophan rotamer model, such a shift is not observed in NATA. Using amplitudes obtained by global analysis, decay-associated spectra of these lifetimes were constructed.
Stortelder
Aike
A
Department of Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit, Faculty of Sciences, Laser Centre VU, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
Buijs
Joost B
JB
Bulthuis
Jaap
J
Gooijer
Cees
C
van der Zwan
Gert
G
D015394:Molecular Structure; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors; D014364:Tryptophan / Q000031:analogs & derivatives / Q000032:analysis* / Q000737:chemistry
D014364:Tryptophan