Knowledge Bank

The Schuman-Runge bands of molecular oxygen have been observed in absorption between 1900 A and about 1700 A in matrices containing up to 10% of oxygen at liquid helium temperature. Nitrogen and argon were used as matrix materials. The gaseous mixtures were deposited on a lithium fluoride window cooled to $4.2\circ K$. Hydrogen, xenon and krypton sources were used as emitters of continua in the spectral regions investigated. Discrete bands were observed between $v1=4v1=15$. The vibrational spacing closely resemble those of the bands of the gas but the bands are shifted to shorter wavelengths by $650cm-1$. The results indicate that the matrix does not noticeably affect the shape of the potential energy curve of the molecule out to an internuclear distance which is twice the equilibrium distance in the ground state. The continuum which follow the bands to shorter wavelengths also closely resembles that observed in the spectrum of the free molecule.