Knowledge Bank

The fundamental vibration-rotation band of pure $Cl2$ has been observed in the density range 1 to 7 relative units at $298^{\circ} $K. A red shift of $4cm-1$ has been observed in the vibrational frequency which has been shown to be not due to isotope effect but to a perturbation of the vibrational energy levels during collisions. The integrated absorption coefficient has been measured and the binary and ternary absorption coefficients determined. From these coefficients it is suggested that the O and S branch intensities of the band are due largely to double transitions.