11 June 1952

Dr. Lindsay Helmholz

Department of Chemistry

Washington University

St. Louis, Missouri

Dear Lindsay:

I was interested to see your paper, with Wolfsberg, in the last issue of the Journal of Chemical Physics.

I am curious to know whether similar agreement between theory and experiment can be obtained with the valence bond treatment, but I have not been able to find my original calculations, made some years ago. Perhaps you checked up on this point, and could tell me in particular whether the first transition and second transition are predicted with the correct ratio of wavelengths, and whether the predicted intensities are satisfactory. I suppose that if the symmetry character of the electronic states is the same for the valence bond treatment as for the molecular orbital treatment, the discussion of interaction with vibrational levels would not be changed.

Have you seen the paper on oxygen complexes of this sort that I had in the Journal of Physical Chemistry a few months ago? I am not sure that it is pertinent to the question of color.

I trust that you are getting along well. I haven't seen anybody from St. Louis recently, except Compton, Shaffer, and recently Barry Wood - he attended the meeting of the Panel on Research of the President's Commission on the Health Needs of the Nation two weeks ago, at which I also was present.

With best regards, I am

Sincerely yours,

Linus Pauling:W