4 μ band radiation from high temperature air

Abstract

Experimental measurements are reported on high temperature air and other gases to establish the source of a band of radiation observed at 4·0 μ. Both a 1 atm arc jet and a shock tube were used to provide a temperature range of 5400–8000°K in air. Experiments established that the radiation was not due to common impurities, and that both O 2 and N 2 are necessary for its appearance. Measurements made on the arc facility with 60 Å resolution showed definite structure and indicate that the radiation is a compact molecular band. The arc and shock tube data can be correlated by assuming that the radiation originates from NO with an excitation energy of about 8 eV. Attempts to identify the band with a transition between known Rydberg states of NO were unsuccessful, but a possibility exists that the transition could occur because of an interaction between certain Rydberg and non-Rydberg states.