λ 3240 band of NH

Abstract

Recently, during use of a heavy current discharge tube for producing the continuous spectrum of hydrogen, it was observed that the well-known λ 3360 band of NH was very well developed when there was a trace of nitrogen in the tube. It was further observed that the band thus produced did not exhibit the strikingly symmetrical structure shown in the ammonia-oxygen flame. This loss of symmetry was found to be due to the presence of a second band at λ 3240, degraded to the red and overlapping the R-branch of the λ 3360 band. The new band also showed the open structure characteristic of light hydride molecules; the spacing of its lines indicating a molecular weight about that of NH. Considering the proximity of this band to the λ 3360 band it seemed strange that it should not be equally well known. An examination of the NH spectrum as obtained under various other conditions was therefore made. A Fowler and Gregory have published photographs obtained from the oxy-ammonia flame and from imperfectly dried cyanogen burning in an atmosphere of oxygen. The λ 3240 band is absent in both cases, although the λ 3360 band appears with great intensity. On the other hand, it appears strongly together with the λ 3360 band in the chemi-luminescence spectrum of N 3 Cl and HN 3 obtained by K. Gleu. It was also obtained in spectra due to excitation of ethyl and propyl iodides by active nitrogen in certain experiments made by Dr. H. T. Byck.