Fine Structure in the Hydrogen Band Lines

Abstract

WE have recently had an opportunity of examining the spectrum of H2 in a large Hilger quartz spectrograph crossed by a reflection echelon. The method, of which an account by one of us (W.E.W.) is being prepared for publication elsewhere, gives a record of the structure of all the lines of fair intensity. So far we have only had time to examine a small number of typical lines, but the results are very interesting. The alternate strong lines of two typical bands which end on the 2p 3IIab levels are all found to be double with the weaker component on the long wave-length side. (No description of the bands ending on the 2p 3II levels has yet been published, but an account of these band systems by Richardson and Davidson has been communicated to the Royal Society.) For example, in the 0→0 band of 3d 3→σ2p 3II we find that the Q1 line 5931.368 is definitely double, the components having an intensity ratio of about 3 to 1 and a separation Δv about 0.21 wave number. Q3 = 6002.816 is an incompletely resolved doublet with Δv about 0.17. R2 = 5938.620 is an unresolved doublet with Δv about 0.11. R4 = 5982.561 is not a simple line, but it is too weak and hazy to estimate the separation. In the 1→1 band of the same system Ql = 6021.273 is a very clear doublet with intensity ratio about 5 to 3 and Δv about 0.21. R2 = 6027.977 is an unresolved doublet with Δv about 0.08.