Implementation of coherent Raman detected electron paramagnetic resonance

The technique of coherent Raman (optically) detected electron paramagnetic resonance (ODEPR), is a relatively new method for the investigation of electronic structure. In this thesis the technique is implemented with a microwave frequency of 35 GHz for the first time. Two continuous wave (cw) ODEPR spectrometers have been built (14 and 35 GHz). Pulsed microwave excitation is possible at 14 GHz. The application to ruby demonstrates the working of the technique and the equipment. When ODEPR is used to analyse metalloproteins, conventional methods like electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) are additionally needed. These have also been implemented and they are demonstrated on myoglobin (Mb).The technique of coherent Raman (optically) detected electron paramagnetic resonance (ODEPR), is a relatively new method for the investigation of electronic structure. In this thesis the technique is implemented with a microwave frequency of 35 GHz for the first time.Two continuous wave (cw) ODEPR spectrometers have been built (14 and 35 GHz). Pulsed microwave excitation is possible at 14 GHz.The application to ruby demonstrates the working of the technique and the equipment.When ODEPR is used to analyse metalloproteins, conventional methods like electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) are additionally needed. These have also been implemented and they are demonstrated on myoglobin (Mb)

Probing the electronic structure of transition metal ion centres in proteins by coherent Raman detected electron paramagnetic resonance spectroscopy

The simultaneous excitation of a paramagnetic sample with optical (laser) and microwave radiation can cause an amplitude or phase modulation of the transmitted light at the microwave frequency. The detection of this modulation indicates the presence of coupled optical and electron paramagnetic resonance (EPR) transitions in the sample. Here we report the first application of this technique to a biomolecule: the blue copper centre of Pseudomonas aeruginosa azurin. Using optical excitation at 686 nm, in the thiol to copper(II) charge transfer band, we measure a coherent Raman-detected EPR spectrum of a frozen aqueous solution. Its lineshape is characteristic of the magnetic circular dichroism along each principal g-value axis. This information allows electronic and structural models of transition metal ion centres in proteins to be tested