INFRA-RED ABSORPTION BANDS OF HYDROGEN 

 CYANIDE IN GAS AND LIQUID 



Bv F. S. BRACKETT, 



CHIEF, DIVISION OF RADIATION AND ORGANISMS, SMITHSONIAN INSTITUTION, 



AND 



URNER LIDDEL, 



FERTILIZER AND FIXED NITROGEN INVESTIGATIONS 

 BUREAU OF CHEMISTRY AND SOILS, U. S. DEPARTMENT OF AGRICULTURE 



INTRODUCTION 



The absorption spectrum of hydrogen cyanide in gas phase in the 

 region from t,ix to i^/J- was investigated originally by W. Burnieister/ 

 and more recently at higher resolution by E. F. Barker/ These investi- 

 gations have shown the presence of a strong doublet at 14/A, weaker 

 bands at 7^, 4.7/A, and 3.6jU., with another. very strong band at S-O^/x. 

 Whereas the frequency relations supported the view earlier held that 

 the yfjL, 4.7,«, and t,.6/j. bands were respectively second, third, and 

 fourth harmonics of a fundamental at 14/^, the intensity of the 4.7/j- 

 band led Barker to question this interpretation and to suggest that 

 very likely a new fundamental was present at approximately the same 

 wave-length as the third harmonic. The 3.6/x band is thus more 

 likely to be a coml)ination of the new fundamental at 4.7/x, with the 

 lower frequency vibration. 



The band occurring at 3.04/A is recognized as another fundamental. 

 The bands at 14/x and 7/x are clearly of the doublet character. Mol- 

 ecular moments of inertia are readily calculated from these data. From 

 Burmeister's curves for the 14/^ band, yielding an apparent separation 

 of maxima of 37.5 cm."\ one calculates a moment of inertia of 

 33 X I0"*° g. cm.- If, however, the relatively large slit-width at which 

 this work was carried out is taken into account, estimates may be 

 made as to the degree of overlapping, and more probable positions of 

 the two components of the doublets may be plotted from the com- 

 posite curve. On this basis a larger separation is obtained, of the 

 order of 50 cm. \ The y/x band was investigated by Barker at suf- 

 ficiently high resolution so that no such correction needs to be made. 



^Verh. Deutsche Phys. Ges., vol. 15, p. 589, 1913. 

 " Phys. Rev., vol. 23, p. 200, 1924. 



Smithsonian Miscellaneous Collections, Vol. 85, No. 5 



