Measurement of time-resolved circular dichroism signals can be complicated by transient linear dichroism and birefringence effects. These signals arise from using a polarized light beam for excitation and from imperfect modulation of the circularly polarized probe beam. In a polarization-modulation experiment designed to measure the time dependence of circular dichroism, a small amount of pump-induced linear dichroism coupled with birefringence of optics would dominate the observed signals, rendering an accurate measurement virtually impossible. We examine these effects within the Jones matrix formalism. These calculations demonstrate how one can experimentally eliminate transient linear polarization signals, permitting accurate measurement of the transient circular dichoism of a sample with picosecond resolution. Theory and experiment are compared for time-dependent data on myoglobin following the photoelimination of CO from carbonmonoxy myoglobin.
© 1990 Optical Society of America
Original Manuscript: July 20, 1989
Manuscript Accepted: November 8, 1989
Published: August 1, 1990
Xiaoliang Xie and John D. Simon, "Picosecond circular dichroism spectroscopy: a Jones matrix analysis," J. Opt. Soc. Am. B 7, 1673-1684 (1990)