Changes in the Optical Properties of Photochromic Compounds: Use of Lightway™ Photoreaction Evaluation System

Introduction

Photochromism refers to the phenomenon of reversible change in the optical properties of substances when irradiated by light. Although these photogenerated changes in the optical properties of substances are caused mainly by isomerization of the molecular structure, they may also be caused by dissociation of dimers. From the viewpoint of thermal stability, photochromic compounds are classified as P-type or T-type. The P-type compounds are thermally-stable compounds which are formed by photoirradiation, and a second irradiation is necessary for reversibility. The T-type compounds are also formed by light irradiation but are thermally reversible. Photochromic compounds are applied as light-modulating materials, photomemory materials, and optical sensors. So-called dimming sunglasses (photochromic sunglasses) are one familiar use of photochromic compounds. The Lightway *1 photoreaction evaluation system developed by Shimadzu Corporation measures the absorption spectrum during photoirradiation of a sample, and enables easy observation of the process of change in photochromism. This article introduces observation of the changes in the optical properties of commercially-available photochromic compounds when irradiated with light.

August 18, 2020 GMT