MAGNETIC VIBRATIONAL CIRCULAR DICHROISM OF PORPHYRINS AND SELECTED GAS PHASE MOLECULES

Croatto, Paul Vincent.

Abstract

Magnetic Vibrational Circular Dichroism (MVCD) is a recently discovered phenomenon in the field of optical activity which provides information regarding the behavior and vibrational motion of molecules subject to high magnetic fields. This current study is a continuation of the experimental study of the MVCD phenomenon.

Adapting FTIR spectroscopy to MVCD resulted in higher MVCD signal to noise, higher resolution, and extension of MVCD to 770 cm^-1, and measurement of a new phenomenon: rotational MVCD.

The porphyrins were predicted by a vibronic coupling model to have large MVCD. The porphyrins gave the largest MVCD solution phase signal to date for the C=C and C=N stretching vibrations.

An application of MVCD is in symmetry assignments of ir band. Many bands in the complicated ir spectra of porphyrins can be assigned along with the band shifts in the deuterated isotopomers.

The gas phase results produced rotationally resolved MVCD which measures changes in rotational angular momentum. Excited state properties can also be measured in molecules without a permanent dipole moment.