Nanosecond time-resolved circular dichroism measurements using an upconverted Ti:sapphire laser

Several years ago a time-resolved circular dichroism technique for the far ultraviolet spectral region with submicrosecond (10(-7) s) time resolution was developed using a xenon flash lamp probe source for measurements of circular dichroism (CD) signals. Recent improvements in Ti:sapphire lasers, providing the ability to frequency-convert the fundamental outputs to produce second, third, and fourth harmonic pulses, allow single wavelength measurements of CD with nanosecond (10(-9) s) time resolution over a broad spectral region (205-910 nm). This provides a powerful technique to study fast biophysical phenomena such as protein folding processes. In this article, the methodology and preliminary application of this new technique are presented. (C) 1996 American Institute of Physics.