Resonance Raman (RR) spectra are reported for five hemoproteins: (a) ferrocytochrome b5; (b) oxyhemoglobin; (c) ferricytochrome 65; (d) deoxyhemoglobin; and (e) methemoglobin. Compound a shows background fluorescence bands which give evidence for incomplete vibrational relaxation. Relative fluorescence yields for (a):palladium mesoporphyrimzinc mesoporphyrin are 1:2.5 X 102:104. Compounds (b) through (e) show no fluorescence but decreasing RR intensity. The presence of fluorescence in (a) and the decreasing RR intensity of (a) through (e) are attributed to decreasing electronic radiationless decay times, re, from 100 to 3 fs across the series (a) > (b) > (c) ~(d) > (e). The times re are estimated from the resolution of the visible absorption bands. Iterative extended Hückel calculations are used to rationalize re: Thus for (a) the visible band is ^( , *) and at lower energy the only state of the same spin is 1(d,d); for (b) at lower energy than 4Q(ir,ir*) there is not only a possible 1(d,d) state but singlets involving transitions on the O2 ligand and charge transfer singlets ring -» oxygen; for (c) the visible excited state is 2Q(tt,t*) and there are 2(d,d), 2(ir,d), and 2 ( , *) excited states at lower energy; similarly for (d) there are 5(d,d) and 5 ( , *) at lower energy than the visible state 5Q(t,t*); finally (e) has both ánd 6(Tr,d) electronic states in the visible energy region with heavy vibronic mixing between them. The roles of photon coherence time, rp, and vibrational relaxation, rv, in determining the nature of the scattering process are explored.

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Observations of nonequilibrium phenomena on the Saturn satellite Titan indicate the occurrence of organic chemical evolution. Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are assessed. Experimental results and theoretical modeling studies suggest that the organic chemistry of the satellite is dominated by two atmospheric processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated in various levels of the atmosphere by cosmic ray, Saturn ‘wind,’ and solar wind particle bombardment of a CH4‐N2 atmospheric mixture can account for the ultraviolet‐visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere, photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. Hot H atom reactions initiated by photodissociation of NH3 can couple the chemical reactions of NH3 and CH4; if 0.1% of the incident ultraviolet light from 1600 to 2270 Å reaches the lower atmosphere, these reactions will be capable of producing organic matter at a rate comparable to or higher than that resulting from particle‐initiated reactions. Electric discharges are highly improbable on Titan; if they occurred at all, they would be restricted to the lower atmosphere and clouds. Their yield of organic matter might approach that of hot H atom reactions if the conversion of solar to electrical discharge energy on Titan was as efficient as that on earth. These assessments indicate that future missions to Titan should include organic chemical analyses of its atmosphere and surface among the prime science objectives.

AbstractsIt is demonstrated for a spin-free, nonrelativistic, complete molecular Hamiltonian that there is an optimal solution to the separation of electronic and nuclear motions. The adiabatic approximation is obtained as a special limiting case. A fruitful interpretation of intermolecular correlation results from the assumption that such correlation involves the degeneracy of a molecular-energy state of one molecule with that of another chemical species, e.g., cubane and cyclooctatetraene. As a consequence, rigorous relationships are established for the influence of nodal patterns of the electronic functions on intermolecular correlation. Also derived are stringent symmetry rules which both electronic and nuclear functions involved in the correlation must obey. Throughout the treatment is a many-electron one.11 est dtmontrt, que pour un Hamiltonien moliculaire sans spin, non-relativiste et complet il existe une solution optimale du probltme de stparer les mouvements Clectroniques et nucltaires. L'approximation adiabatique est obtenue comme un cas special. Une interpretation fertile des resultats sur la corrilation intermoltculaire dtcoule de l'hypothkse qu'une telle correlation entraine une degtntrescence d'un itat Cnergetique d'une molecule avec celui d'une autre molecule, comme par exemple cubane et cyclooctatetrakne. Par consequent on ttablit des relations rigoureuses pour dtcrire I'influence du systtme de noeuds des fonctions Clectroniques sur la corrtlation intermoltculaire. O n obtient aussi des rtgles de symetrie strictes satisfaites par les fonctions Clectroniques et nucleaires. Dans I'article entier on se place sur le niveau de N tlectrons.Es wird gezeigt, dass fur einen spinfreien, nicht-relativistischen, vollstandigen molekularen Hamiltonoperator eine optimale Losung existiert fur das Problem die Bewegungen der Elektronen und Kerne zu separieren. Die adiabatische Naherung wird als spezieller Grenzfall erhalten. Eine ergiebige Interpretation der intermolekularen Korrelation wird erhalten, wenn man annimmt, dass eine solche Korrelation die Entartung eines Energiezustands eines Molekuls mit dem eines anderen, 2.B. Kuban und Zyklooktatetraen, mit sich bringt. Folglich werden strenge Beziehungen erhalten fur die Einwirkung des Knotensystems der elektronischen Funktionen auf die intermolekulare Korrelation. Weiter werden strenge Symrnetrieregeln abgeleitet, die von sowohl elektronischen als auch Kernfunktionen befriedigt werden mussen. Die Behandlung wird durchaus auf dem Vielelektronenniveau ausgefuhrt.