EXCITATION OF POLYENES AND PORPHYRINS 121 



(1950c) Some studies in molecular orbital theory. III. Substitution in 



aromatic and heteroaromatic systems. J. Chem. Phys., 18: 283-291. 



Longuet-Higgins, H. C, C. W. Rector, and J. R. Piatt (1950) Molecular orbital 

 calculations on porphine and tetrahydroporphine. J. Chem. Phys., 18: 1174- 

 1181. 



McClure, D. S. (1949) Triplet-singlet transitions in organic molecules. Lifetime 

 measurements of the triplet state. J. Chem. Phys., 17: 905-913. 



McConnell, H. (1952) Effect of polar solvents on the absorption frequency of 

 n ^^ TT electronic transitions. J. Chem. Phys., 20: 700-703. 



Merkel, E., and C. Wiegand (1947) Beziehvmgen zwischen Ultraviolettabsorption 

 und Molekiilaufbau. Naturwissenschaften, 34: 122. 



Moodie, M. M., and C. Reid (1952) Inter- and intramolecular energy transfer 

 processes. II. Hydrocarbon-hydrocarbon systems. J. Chem. Phys., 20: 1510- 

 1515. 



MuUiken, R. S. (1939) Intensities of electronic transitions in molecular spectra. 

 I. Introduction. J. Chem. Phys., 7: 14-20; II. Charge-transfer spectra. Ibid., 

 20-34; III. Organic molecules with double bonds. Conjugated dienes. Ibid., 

 121-135; IV. Cyclic dienes and hyperconjugation. Ibid., 339-352; V. Ben- 

 zene. /5w/., 353-356; VI. Alolecular refractivities of organic compomids. Ibid., 

 356-363; VII. Conjugated polyenes and carotenoids. Ibid., 364-373; Villa. 

 Odd-numbered conjugated polyene chain molecules and organic dyes with notes 

 on optical anisotropy and Raman intensities. Ibid., 570-572. 



Mulliken, R. S., and C. A. Rieke (1941) Molecular electronic spectra, dispersion, 

 and polarization; the theoretical interpretation and computation of oscillator 

 strengths and intensities. Repts. Progr. Phys., 8: 231-273. 



Mulliken, R. S., and C. C. J. Roothaan (1947) The twisting frequency and the 

 barrier height for free rotation in ethylene. Chem. Revs., 41: 219-231. 



Pauling, L. (1945) The nature of the chemical bond and the structure of molecules 

 and crystals. 2nd ed., Cornell University Press, Ithaca, N.Y. 



Pinckard, J. H., B. Wille, and L. Zechmeister (1948) A comparative study of the 

 three stereoisomeric 1,4-diphenylbutadienes. J. Am. Chem. Soc, 70: 1938-1944. 



Piatt, J. R. (1949) Classification of spectra of cato-condensed hydrocarbons. J. 

 Chem. Phys., 17: 484-495. 



(1950) Molecular orbital predictions of organic spectra. J. Chem. Phys., 



18: 1168-1173. 



(1951a) Isoconjugate spectra and variconjugate sequences. J. Chem. Phys., 



19: 101-118. 



(1951b) Spectroscopic moment: a parameter of .substituent groups deter- 

 mining aromatic ultraviolet intensities. J. Chem. Phys., 19: 263-271. 



(1951c) Experimental determination of even-odd character of excited elec- 

 tronic states of molecules with a center of symmetry. J. Chem. Phys., 19: 

 1418-1419. 



(1953a) Classification and assignments of ultraviolet spectra of conjugated 



organic molecules. J. Opt. Soc. Amer., 43: 252-257. 



(1953b) Free-electron network model for conjugated systems. III. A demon- 



stration model showing bond order and "free valence" in conjugated hydro- 

 carbons. J. Chem. Phys., 21: 1597-1600. 



Piatt, J. R., H. B. Klevens, and W. C. Price (1949) Absorption intensities of ethylene 

 and acetylene in the vacuum ultraviolet. J. Chem. Phys., 17: 466-469. 



Pruckner, F. (1940) Lichtabsorption und Konstitution der Chlorophyllderivate. 

 II. Z. physik. Chem., A187: 257-275. 



(1941) Lichtabsorption und Konstitution der Chlorophyllderivate. III. 



Absorption der Dioxykorper. Z. physik. Chem., A 188: 41-59. 



