The ionisation of nitrogen by electron impact

Abstract In a previous paper the writer suggested a new mode of attack on some ionisation problems and described its application in experiments on mercury vapour. The object of the method is to give a direct means of studying the types of ion produced in a gas or vapour by electrons of known speed. The experimental principle involved is the combination of an ordinary ionising potential apparatus with an arrangement for positive-ray analysis. It does not seem necessary to repeat the general discussion of the advantages to be gained or the difficulties to be overcome in using such a method. Suffice it to say that at first it appeared impossible to deal with substances gaseous at ordinary temperatures, but that now the method has been extended to include them. The nature of the difficulty and the manner in which it can be overcome are best understood by passing directly to the experiments on nitrogen, which are the subject of the present paper.