182 for one of the compounds. Compounds 3, 6, and 7 were studied previously, but have been restudied in order to obtain more complete and accurate data. The numbers used to designate these correspond with those used in the previous report. Numbers 8 through 13 are additional compounds. Except as indicated below, the wavelengths which could be studied are in - the first absorption band of the compound. Some experimental details are as follows: short-wavelength end of the first absorption band. Two possible explanations suggest themselves, either or both of which could be involved in a given instance. (a) Broadly speaking, the shorter the wavelength absorbed, the higher the vibrational state to which the molecule is raised and the greater the excitation energy involved in the instantaneous (10~” second) vibrational-relaxation process which follows. To If the molecules having had the greater excitation energy now end up with greater rotational energy, which they retain during the period preceding emission, then greater depolarization would be observed mu. In all cases signals were sufficiently large to permit use of such narrowslits. No set rule was followed concerning the number of times a measurement was to be repeated; however, enough repetition was carried out to make a result convincing, especially where tween the first. and second absorption bands, and if the second band is of the opposite type (as regards 90° shift or no shift) the two opposite polarizations achieve maximum spectral purity, monochromator slits were kept very narrow, 0.9 and 0.6 mm, respectively, for entrance and exit slits; this corresponds to a half-intensity band width of only 1.6 it seemed crucial. In general, because of the great varlations in absorbance of a solution at the different wavelengths, more than one concentration of solution was needed in covering each spectrum. In the first report, mention was made that (for the for them. (b) There may be a region of overlap be- will tend to cancel each other. For compound 13 (see also Figure 139), it was possible to extend the measurements into the second absorption band, and explanation (b) seems to be confirmed, although (a) may be involved as well. Second, hidden transitions seem likely or possible in two of the compounds-— in compound 6 at about 330 my and in compound 7 at particular geometry of our apparatus) calculations showed that maximum signal would result when the absorbance is 0.9. However, it was found that solu- about 320 mp. It might be added at this point that both positive and negative polarizations were observed, that the most positive and most negative values (+45 and antly omitted from the polarimeter diagram of the first report) which sends the incident beam back through the cell. Evidently this is more effective than was assumed. A test was performed to learn something of the magnitude of the signal, produced by incident light theoretical limits (+50 and —33144%, respectively), and that, therefore, the observations attest to the reliability of the apparatus. tions somewhat more dilute than this gave stronger signals. In the cell chamber is a reflector (inadvert- scattered in the cell, reaching the photomultiplier after attenuation by the appropriate fluorescent-beam filter. The polarimeter was operated with the solvent alone in the cell (fluorescent solute missing} and signals recorded for each filter used at each incidentlight wavelength used. Because of xenon-source instability, mentioned in the first report, readings taken at different times have been found to vary consider- ably; however, if the values obtained in this test were to be used as signal corrections, the effect on P (expressed as percent) would be to change it (negatively) by only 0.1 in 70% of the instances and by no more than 1 in any instance. Considering this and other possibilities for error, the total uncertainty in P is perhaps no greater than 2 [that is, P = 41% means P = (41 + 2)%, etc]. Certain features of the results in Table 66 are of particular interest. First, in every instance, the polar- ization drops as one moves from the long- toward the —19%, respectively) were reasonably close to the INTRINSIC VISCOSITY STUDIES Tests in which depolarizations of the three binaphthy] derivatives are compared are continuing, but as yet, because of our inability to secure sufficiently precise and reproducible results, no conclusion has been reached as to whether there are or are not differences among them. Tentatively, one might conclude that if there are effects, they are of small mag- nitude. Temperature control is no longer a major problem; other factors appear to interfere and need to be investigated. A slight change in the position of the cell or in the level of the liquid in it may affect the results enough to obscure the effect. Also, certain observations have suggested that the compounds used may undergo a photochemical reaction when exposed to the UV radiation. 'REFERENCES 1. Anderson, W. R., Berlman, I. B., and Wirth, H. O. Argonne National Laboratory Radiological Physics Division Annual Report, July 1966-June 1967. ANL 7360, pp. 1-4. 2. Platt, J. R. J. Chem. Phys. 17, 484-495 (1949).