Polarization spectrophotometer for measurements of both polarized emission and excitation spectra

Abstract

The construction of a polarization spectrophotometer coupled with a microcomputer is described. The new spectrophotometer enables the continuous recording of a polarized emission spectrum of luminescent molecules as well as a polarized excitation spectrum. The instrument’s optics were designed to separately detect each polarized component of the emission utilizing an optical fiber bundle composed of two blanches. The use of the optical bundle, along with phase-sensitive detectors, permits precise polarization measurements at low signal-to-noise ratios and, at the same time, affords a high degree of immunity from artifacts arising from the measurement of the polarized spectrum of emission. Data acquisition and various manipulations, such as instrument response and polarization calculations, were performed by a Fujitsu Micro 8 microcomputer equipped with an 8-bit analog-to-digital converter. Several examples of the instrument’s performance are provided including a polarized phosphorescence emission spectrum of 0.05 mM indole in ethylene glycol–water (v/v=1) at 77 K.