September 18, 1944
Professor G. N. Lewis
Department of Chemistry
University of California
Berkeley 4, California
Dear Professor Lewis:
I have been very interested to read your paper in the last Journal on the absorption and fluorescence of hydrocarbon free radicals. I happened to notice that it is possible to interpret the vibrational fine structure which you have observed by the use of the available data from the Raman effect. The principle Raman lines for a mono-substituted benzene correspond to frequency shifts of about 200, 620, 820, 990, 1030, 1160, 1200, 1580, 1600, and about 3000 cm.-1 These Raman shifts correspond very closely to your bands 1 to 7: indeed, from your Figure 2 I would judge that your band No. 6 might well have a fine structure corresponding to the lines 1030, 1160, and 1200. Perhaps your lines 8, 9, and 10 are overtones or combinations of the Raman lines, or fundamentals forbidden in Raman scattering.
With a little better resolution your technique might well provide a great deal of interesting information about the vibrations of di-molecules.
I have just returned from a trip to Washington, where, among other activities, I had a talk with Chadwell about a problem in which he is interested. He mentioned that he had also written to you about this matter. We are going to do a small amount of work in connection with this problem, and I have hopes that some good results will come out of the work.
Helen and I are still hoping that we can come to Berkeley for a visit before long, perhaps in two or three months. We shall look forward to seeing you and Mrs. Lewis again.
Sincerely yours,
Linus Pauling
LP:jr
September
18, 1944
