FAST NATURAL AND MAGNETIC CIRCULAR-DICHROISM SPECTROSCOPY

The addition of circular or, more generally, elliptical polarization s tate detection to fast optical absorption spectroscopy can increase th e amount of electronic and nuclear conformational information obtained about transient molecular species. To accomplish this, fast circular dichroism methods have emerged over the past decade that overcome the millisecond limit on time resolution associated with conventional modu lation techniques and enable structural studies of excited states and kinetic intermediates. This article reviews techniques for time-resolv ed natural and magnetic circular dichroism spectroscopy covering the p icosecond to millisecond time regimes and their applications, with par ticular emphasis on quasi-null ellipsometric techniques for nanosecond multichannel measurements of circular dichroism. Closely related quas i-null polarimetric techniques for nanosecond optical rotatory dispers ion and linear dichroism measurements are also discussed.