ETTORE CASTIGLIONI
JASCO Europe srl, via Cadorna 1, Cremella (LC), I 23894, Italy.Dipartimento di Scienze Biomediche e Biotecnologie, Università di Brescia, viale Europa 11, Brescia, I 25123, Italy

Abstract

A very short paper of December 1960, by French researchers, presented an innovative way to measure circular dichroism. This approach quickly became an alternative and, in a few years, nearly replaced the optical rotary dispersion technique in the measurement of chiral samples. Progress in optics and electronics notwithstanding, the same design and technology is still used, with little modification, today.

INTRODUCTION

In the third quarter of the last century an impressive number of academic papers and industrial researches focused on the development of optical rotary dispersion (ORD) spectropolarimeters. This work was stimulated by the growing demand of organic chemists, more and more involved in the study of chirality, and by the discovery of the rich amount of conformational information available for biomolecules in the UV range.
Several instrument manufacturers introduced ORD spectropolarimeters for the UV-Vis range, mainly based on different variants of the conventional optical null method used in single wavelength polarimeters (1), including the following: Rudolph and Cary in US, JASCO in Japan, Bendix in UK, Perkin-Elmer and Zeiss in Germany.
This trend lasted only a few years: in 1960 a French group presented an innovative approach to measure circular dichroism (CD) based on the use of a Pockels cell as an electro-optic retardation modulator (2). The technique was patented by Roussel-Uclaf and Jouan (later Jobin-Yvon) started the industrial production of a commercial model, the Dichrograph.
ORD and CD give substantially the ...