POLARIZATION MEASUREMENTS WITH THE CARY MODEL 81 RAMAN SPECTROMETER
Loading...
Date
1967
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The recent addition of the capability for laser excitation to the Model 81 Raman Spectrometer has prompted a re-examination of the techniques used for measurement of depolarization ratios. Classical measurements employing natural exciting light sources (e.g. the Toronto arc) gave rise to maximum values of 6/7 for depolarized lines. With laser excitation, the source is initially linearly polarized and the measurement may be made in two ways which are shown to be mathematically and experimentally equivalent. In the first more classical method, the two orthogonal vectorial components of the Raman radiation are ratioed, care being taken to compensate for the polarizing characteristics of the monochromator; in the second and more experimentally convenient method, only the more efficiently transmitted component of the Raman radiation is passed through a Polaroid sheet analyzer, but the direction of the vector of the exciting light is turned through $90^{\circ}$ by rotating a half-wave plate, to give the two values of intensity which are ratioed. Both methods give maximum values of 3/4 for depolarized lines. The suggested technique will be illustrated from studies made on liquids with a multi-pass excitation cell and with single oriented crystals utilizing a new goniometric crystal holder which allows 3 degrees of freedom of rotation.
Description
Author Institution: Cary Instruments