II. Ultra-violet characteristics of the flash discharge

Abstract

The ultra-violet characteristics of the continuous spectrum emitted by the gaseous flash discharge have been examined by photometric and actinometric methods. The dependance of (a) energy distribution with wave-length and (b) total output in the photochemically useful region, on parameters such as energy of the discharge and nature and pressure of the gas filling is investigated. The energy emitted is independent of wave-length in the region 2600 to 4400 angstrom, whilst the energy distribution is independent of the nature of the gas filling, and also of the gas pressure and the energy input above certain critical limits. Above these limits the total output is given by the expression J$_{u}$ = kC(V$^{2}$-V$_{0}^{2}$), where k is a constant depending on the over-all efficiency of the experimental arrangement. Owing to the extreme sensitivity of V$_{0}$ to traces of impurity in the gas filling, the output per flash of 2500 J for different fillings may vary by $\pm $ 10%. For any one filling the output is reproducible within the analytical accuracy. The results are discussed in relation to the mechanism of production of the continuum which is attributed to the recombination radiation of electrons.