No abstract

No abstract

have recently shown that rhombic sulphur consists of S 8 molecules; the atoms in each molecule are located at the corners of a puckered octagon. We will now apply the methods based on group theory as developed by Wigner, 2 Tisza, 3 and others for investigating the normal modes of oscillation of such a molecule. There are sixteen symmetry operations which transform the model into itself and these operations form the point group S,8«. There are seven irreducible representations for this group and the character Table I obtained from the general tables given by Tisza is given.The significance of hj t x/, n% and m' is the same as that in a recent paper by Wilson. 4 The activity or otherwise of these oscillations is also given in the last two columns of the table. P indicates a strong and well-polarized Raman line. D indicates a completely depolarized Raman line and / stands for a forbidden line. The table shows that we should expect two strong and well polarized lines and five depolarized lines in the Raman spectrum of sulphur.Venkateswaran 5 has recently obtained the complete Raman spectrum in which eight lines at 88, 114, 152, 185, 216, 243, 434 and 468 have been recorded. He has given good reasons to show that the lowest frequency is to be attributed to the lattice and not to the molecule. The molecular frequencies are therefore only seven and two amongst these, namely 216 and 468, have been found to be strong and well polarized in complete accord with our conclusions. These two represent the total symmetric vibrations A\. All the other five, namely 114, 152, 185, 243 and 434 should be completely depolarized according to the theory. The stronger of these (152 and 434) have been found to be so but data in respect of others are not given by Venkateswaran presumably because they are weak. The Raman spectrum data so far as are available may thus be taken to be in complete accordance with the model proposed by Warren and Burwell. Interpretation of the infrared spectrum and a more detailed analysis of the vibrational modes and frequencies will be given elsewhere.

We have found seven chemically identified radioactive periods of tellurium as the result of deuteron and neutron bombardment of tellurium, fast neutron bombardment of iodine, and deuteron and proton bombardment of antimony. This work has made it possible to make the isotopic assignments for all of the activities and to show that there are three pairs of isomers. The "isomer separation" method of Segre, Halford and Seaborg, 1 as already applied to tellurium, 2 was tried for each of these pairs. It is remarkable that all three isomeric pairs were chemically separable, the short period growing from the long-lived activity in each case.Te 127 : 90 days and 10 hours.-Prolonged bombardment of iodine with the fast neutrons from Li-f-D produces in the tellurium precipitate not only the electron-emitting tenhour activity previously reported 3 but also a new activity with a 90-day half-life. Since there is only one stable iodine the reaction must be I 127 (n, p) Te 127 and both periods must be due to isomers of Te 127 . These activities are produced with much greater intensity by deuteron bombardment of tellurium; it is possible to separate the ten-hour period from tellurium activated in this manner long after the directly formed ten-hour period has completely decayed (in one case, 45 days after the bombardment). The 90-day activity is due to the higher of the two isomeric levels and decays, probably by a converted gamma-ray transition, to the lower level, which then decays with a ten-hour halflife by beta-emission to stable iodine.Te 131 :1.2 days and 25 minutes.-We have already shown 4 that an electron-emitting eight-day iodine grows from a tellurium isotope, necessarily either Te 129 or Te 131 , with both a 1.2-day and a "short" half-life; further work 2 has demonstrated that the period of the shorter-lived parent of the iodine is about 25 minutes. The 1.2-day and 25-minute activities, which are both directly produced by deuteron bombardment of tellurium, are isomeric and isomer separation experiments show that the 25-minute period grows from the 1.2-day activity; it is in fact possible to observe, by successive extractions of iodine, the growth of the eight-day iodine from the 25-minute tellurium activity obtained by extraction from its parent isomer. Bothe and Gentner 5 did not find a 25-minute activity (but did observe a 60-minute period, which aids in assigning another pair of isomers to Te 129 ) when exposing tellurium to gamma-rays; this activation could produce Te 129 but not Te 131 , so it appears that the 1.2-day and 25-minute isomers must belong to Te 131 .Te 129 : 30 days and 70 minutes.-Deuteron bombardment of tellurium also produces a tellurium period of approximately 30-days half-life. Isomer separations show that a 70-minute tellurium activity grows from this 30-day period. The 70-minute activity is also undoubtedly produced directly by deuteron bombardment, but the presence of so many other activities makes it difficult to observe; however, an electron emitting activity with half-life about one hour seem...