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Fluorescence dynamics spectrometer of single-picosecond resolution: optimisation of experimental performance

Karolczak J., Komar D., Kubicki J., Szymański M., Wróżowa T., Maciejewski A.

Bulletin of the Polish Academy of Sciences. Chemistry

1999

Vol. 47, No. 4

361-380

Design and construction of a new spectrometer for picosecond fluorescence decay measurements by time-correlated single-photon counting is described. The use of pico/femtosecond excitation pulses from a tunable Ti: Sapphire laser in combination with a fast microchannel plate photodetector and ultrafast timing electronics resulted in an excellent temporal resolution and stability of the instrument response function (IRF) of the spectrometer which enabled successful analysis of fluorescence decay signals of single picoseconds. Results of optimisation of experimental characteristics of the system concerning the effect of the geometry of the excited region of the sample, optimum optical imaging and performance of photodetectors are presented. Test measurements of fluores-cence decay of xanthione in various solvents characterised by different S(2) state lifetimes 5-38 ps proved the excellent experimental performance of the spectrometer .

Optical calibration of the picosecond time scale and correlated background elimination in fluorescence dynamic measurements by time-correlated photon counting.

Dobek K., Karolczyk J., Komar D., Kubicki J., Szymański M., Wróżowa T.

Optica Applicata

1998

Vol. 28, nr 3

201-207

A simple, feasible and precise method of calibration of the time scale of a TCSPC laser spectrometer is devised, based in the insertion of an optical delay into one of the start/top channels. The delay can vary from a fews ps to about 1 ns depending on the geometry and refractive index of the medium used, and can be determined with an accuracy better than 1%. A procedure is proposed for eliminating the time-correlated background appearing mainly due to Raman scattering and trace impurities in solvents, which is a serious impediment in TCSPC measurements an analysis of excited state decay in the picosecond time scale. The problem of the correlated background elimination is particulary important for sample of the excited state decay time of single picoseconds, which usually show very weak liminescence.