Takahiko MIZUNO, Yasuhiro MIZUTANI, and Tetsuo IWATA^*

Division of Energy System, Institute of Technology and Science, The University of Tokushima, Tokushima 770-8506, Japan

(Received February 29, 2012; Accepted April 6, 2012)

We propose a phase-modulation fluorometer (PMF) with a light-emitting diode (LED) or a laser diode (LD) used as an excitation light source (ELS) that is driven in the phase-modulation (PM) mode. The PM-ELS generates many frequency sidebands that spread in the vicinity of carrier frequency f_c with the interval of modulation frequency f_m depending on the maximum phase deviation Δφ. The scheme enables us to derive fluorescence lifetime values of a multicomponent sample at one time. We show a typical numerical simulation result for explaining the principle of operation. To demonstrate the effectiveness of the proposed PMF, we have measured fluorescence lifetimes of three kinds of inorganic fluorescent glasses and that of a mixture solution of 1× 10^-6 M rhodamine 6G and 1× 10^-6 M coumarin 152 in ethanol with a volume ratio of 1:1.

Key words: phase-modulation fluorometer, phase-modulated light source, fluorescence lifetime, spectroscopic techniques, instrumentation

^*E-mail address: iwata@me.tokushima-u.ac.jp