Analytica zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ChimicaActa, 192 (1987) 145-153 Elsevier Science Publishers B.V.. Amsterdam -Printed in The Netherlands zyxwvutsrqponmlkjihg TIME-RESOLVED FLUORESCENCE WITH AN OPTICAL-FIBER PROBE G. H. VICKERS, R. M. MILLER’ and G. M. HIEFTJE* Department of Chemistry, Indiana University, Bloomington, IN 47405 (US A.) (Received 19th June 1986) SUMMARY Time-resolved fluorescence measurements are made with an optical-fiber probe approximately 16 m long. Fluorescence lifetimes for 1.00 PM solutions of rhodamine-B and rose bengal in ethanol were found to be 2.78 + 0.04 ns and 0.77 ?: 0.07 ns, respec- tively, similar in accuracy and precision to values obtained with conventional techniques. Calculations are used to investigate the limitations in remote determinations caused by temporal broadening. Results indicate that fiber lengths approaching 1 km can be used without significant loss in accuracy or precision. Time-resolved fluorescence has found wide application in the study of excited-state lifetimes of both atoms and molecules. The information pro- vided by time resolution can be used to characterize spectroscopic states, energy-transfer processes, molecular structure, and dynamics in fields as diverse as solid-state physics and molecular biology [ 11. Time resolution can be used also in quantitative methods if the steady-state fluorescence intensity is not sufficient to allow unambiguous characterization of the sample. For example, the individual contributions from fluorophores with strongly overlapping fluorescence spectra, but different lifetimes, can often be determined by using the measured fluorescence decay curve [2, 31, or by simultaneously monitoring the fluorescence with respect to time and wavelength [ 41. Time resolution can assist also in the correction of errors in fluorescence intensity caused by scattered light [5] or the presence of quenching agents [ 61. Most time-resolved fluorescence measurements are done on samples which can be conveniently handled in the laboratory, and numerous instruments and methods have been devised for the study of such samples [l, 71. How- ever, there are occasions when it is either desirable or essential that the sample remains remote from the measurement instrumentation. For example, the sample itself might be too hazardous to be allowed into a normal spectro- scopic laboratory, or may be part of a continuous sample stream in an environment which is inimical to delicate optical and electronic instrumenta- tion. It might be necessary to make in-situ measurements in locations with *Present address: Unilever Research, Port Sunlight Laboratory, Wirral, Merseyside, L63 3JW , Great Britain. 0003-2670/87/$03.50 o 1987 Elsevier Science Publishers B.V.