Optical Refractivity of High-Temperature Gases. I. Effects Resulting from Dissociation of Diatomic Gases

Abstract

Shock-tube and discharge techniques make it possible to generate in the laboratory significant volumes of dissociated and/or ionized gases. This paper describes some studies of the optical index of refraction μ of dissociated diatomic gases. The physical interpretation of specific refractivity K = (μ − 1)/ρ is discussed and related to polarizability, and various methods of computing such quantities are reviewed briefly. Shock-tube experiments are described in which optical interferometry has been utilized to measure the polarizability of atomic oxygen and nitrogen with the result ᾱ(O I)=0.77±0.06 A3 and ᾱ(N I)=1.13±0.06 A3. The use of optical interferometry for determination of gas density has been justified for experiments involving air at temperatures to at least 5000°K.