Site Selective High Resolution Laser Spectroscopy of Europium in Calcium Binding Proteins

Abstract

Lanthanide ions are generally known to possess narrow 4fn to 4fn transitions in both excitation and fluorescence that are sensitive to the coordination environment surrounding the ion. Selective excitation with a narrowband laser can spectrally discriminate one lanthanide ion environment from another based upon differences in the crystal fields associated with the unique lanthanide ion sites. This paper describes site selective laser spectroscopic experiments where europium ions have been coordinated to proteins in sites normally occuppied by calcium ions.