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15 Jun 1968

Volume 48, Issue 12, pp. 5299-5744

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Torsion–Vibration–Rotation Interactions in Methanol. I. Millimeter Wave Spectrum

R. M. Lees and J. G. Baker

J. Chem. Phys. 48, 5299 (1968); http://dx.doi.org/10.1063/1.1668221 (20 pages) | Cited 206 times

Online Publication Date: 5 September 2003

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In a study of internal rotation in methanol, the millimeter wave spectra of CH3OH, CD3OH, and CH3OD have been investigated between 90 and 200 Gc/sec. In the analysis of the spectra, torsion–vibration–rotation interactions were treated as adjustable parameters in semiempirical formulas. Kivelson's formula for a‐type ΔK  =  0 transitions was tested over a wide range of quantum numbers. It reproduced the CH3OH and CD3OH spectra quite well, but the approximations used in the calculations appear to start breaking down for the larger asymmetry of CH3OD. For assignment of b‐type ΔK  =  ± 1 transitions, a method was developed based on the wide spectral range of the millimeter wave spectrometer. Sufficient b‐type data were obtained for CH3OH to permit a test of Kirtman's formula for origins of Q branches. Convergence difficulties in the Q‐branch least‐squares fit prompted a re‐examination of the theory, which revealed an interesting linear relation coupling six of the parameters. This relation shows that for any molecule the torsional barrier terms V3 and V6, the two moments of inertia about the near‐symmetry axis, and two of the adjustable interaction parameters cannot be independently determined from the spectrum of a single isotopic species. This casts some doubt on values previously reported for V6 in other molecules and adds further uncertainty to V3 determinations. The effective V3 obtained by ignoring torsion–vibration–rotation interactions was found to decrease slightly on deuteration, values of 375.6, 371.8, and 370.3 cm− 1 being obtained for CH3OH, CD3OH, and CH3OD, respectively. Although it is impossible to determine V6 unambiguously from the spectrum of CH3OH alone, a qualitative argument suggests that V6 lies between 0 and −0.8 cm−1. The geometry of the molecule has been completely determined from the experimental data.

Infrared Spectrum of Anthracene Crystals

A. Bree and R. A. Kydd

J. Chem. Phys. 48, 5319 (1968); http://dx.doi.org/10.1063/1.1668222 (7 pages) | Cited 31 times

Online Publication Date: 5 September 2003

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The infrared spectrum of anthracene is reported with the plane of the incident polarized light parallel to all three crystal axes. The measurements were extended to 50 cm− 1; thus the c polarized spectrum was recorded over a sufficient spectral range to cover all fundamentals. Some lattice modes and all the low‐frequency infrared‐active fundamentals (below about 600 cm− 1) were firmly assigned. Some earlier misassignments were corrected and a more probable; though, in part, still uncertain, assignment of the infrared‐active fundamentals at higher energy was made.

Anomalous Viscosity of Critical Mixtures and Its Dependence on Velocity Gradient

Robert Sallavanti and Marshall Fixman

J. Chem. Phys. 48, 5326 (1968); http://dx.doi.org/10.1063/1.1668223 (4 pages) | Cited 16 times

Online Publication Date: 5 September 2003

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The anomalous viscosity is calculated from a direct solution of the differential equation for the perturbed radial distribution function. The resultant expression for the anomalous viscosity is a fourfold integral which depends parametrically on the velocity gradient. A series expansion of the viscosity in powers of the velocity gradient is divergent, but numerical integration yields a well‐behaved non‐Newtonian viscosity.

Avoided Crossings in Bound Potential‐Energy Curves of Diatomic Molecules: Derivation and Analysis of the Vibrational Hamiltonian

J. K. Lewis and J. T. Hougen

J. Chem. Phys. 48, 5329 (1968); http://dx.doi.org/10.1063/1.1668224 (8 pages) | Cited 21 times

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As a first step in analyzing the effect of an avoided crossing on the spectrum of a diatomic molecule, a formalism is presented for dealing with the vibrational problem. A mathematically well‐defined procedure is given for going from potential curves exhibiting an avoided crossing (such as would be obtained by solving exactly the eigenvalue problem associated with the complete electronic Hamiltonian for fixed nuclei) to two crossing potential curves and an interaction function. These latter curves, though less meaningful physically than the former, lead to a pair of relatively simple coupled differential equations (similar to those arising in other vibronic problems) which must be solved to determine the vibrational wavefunctions and energy levels. The order of magnitude and mass dependence of the interaction terms in the coupled differential equations are examined.

Improved Quantum Theory of Many‐Electron Systems. IV. Properties of GF Wavefunctions

William A. Goddard

J. Chem. Phys. 48, 5337 (1968); http://dx.doi.org/10.1063/1.1668225 (11 pages) | Cited 27 times

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The GF method for obtaining accurate many‐electron wavefunctions was described in a previous paper. In this paper, some of the properties of this method are explored, and it is shown that the Hellmann–Feynman, Koopmans', and Brillouin's theorems apply to GF wavefunctions. Calculations are reported on Li2, CH4, and CH3 in order to demonstrate some aspects of the method.

NMR Evidence of H3O+ Ions in Gallium Sulfate

D. W. Kydon, M. Pintar, and H. E. Petch

J. Chem. Phys. 48, 5348 (1968); http://dx.doi.org/10.1063/1.1668226 (4 pages) | Cited 2 times

Online Publication Date: 5 September 2003

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Hydrated gallium sulfate has been studied over a wide temperature range using both steady‐state and transient proton resonance techniques. Second moment and spin–lattice relaxation time data support the suggestion that oxonium H3O+ ions exist in this material and that the structural formula should be written (H3O)Ga3(OH)6(SO4)2. The oxonium ions undergo thermally activated reorientations and translational diffusion. These motions induce dipolar proton spin–lattice relaxations which are most effective at 135° and 300°K, respectively.

Molecular Beam Kinetics: Reactions of K, Rb, and Cs with Cl2

R. Grice and P. B. Empedocles

J. Chem. Phys. 48, 5352 (1968); http://dx.doi.org/10.1063/1.1668227 (6 pages) | Cited 35 times

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Crossed beam studies have been made of the reactions of K, Rb, and Cs atoms with Cl2. These systems are found to exhibit the “stripping” reaction characteristics previously observed for the M + Br2 and I2 systems: (1) the reaction cross sections are very large, ⪞150 Å2; (2) most of the alkali halide product recoils into the forward hemisphere with respect to the incident alkali beam, with scattering angle θ < 60° (in the center‐of‐mass system). However, there also seems to be substantial intensity (∼5%–15% of the forward peak) throughout the backward hemisphere, 90° < θ < 180°. The sharpness of this forward peaking appears to decrease along the sequence Cl2, Br2, I2 and to be relatively independent of the alkali atom; (3) the angular distribution (in the c.m. system) of alkali atoms scattered without reaction falls off much more rapidly at wide angles than for collisions between unreactive molecules of comparable size. The falloff is most rapid for K + Cl2 and somewhat less rapid for Rb and Cs + Cl2, which are roughly comparable with M + Br2; (4) most of the chemical energy released appears as internal excitation of the products, and other evidence indicates that this is predominantly vibrational excitation of the newly formed bond.

Environmental Effects on Phosphorescence. II. “Activation Volumes” for Triplet Decay of Aromatic Hydrocarbons

B. A. Baldwin and H. W. Offen

J. Chem. Phys. 48, 5358 (1968); http://dx.doi.org/10.1063/1.1668228 (3 pages) | Cited 8 times

Online Publication Date: 5 September 2003

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The rate of triplet decay k has been measured to 32 kbar for 20 aromatic hydrocarbons at room temperature. The measured lifetimes are generally shortened by high pressure. The slope of lnk‐vs‐P plots were all linear above 15 kbar. This slope is positive except for terphenyl, and can be related to “activation volumes” ΔV‡ for this kinetic process. The values −1.0 < ΔV‡ < 0.2Å3 / molecule are found for this class of compounds. The perdeuterated compounds have a larger negative “activation volume” than the corresponding perprotonated aromatics. Hence, environmental perturbations are most effective for slow processes which arise from weak intramolecular perturbations in the solute.

Statistical‐Mechanical Calculation of Surface Properties of Simple Liquids and Liquid Mixtures. I. Pure Liquids

Igor W. Plesner and Ole Platz

J. Chem. Phys. 48, 5361 (1968); http://dx.doi.org/10.1063/1.1668229 (4 pages) | Cited 27 times

Online Publication Date: 5 September 2003

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Statistical calculations of surface properties of simple liquids at two different reduced temperatures are presented. Alternatively, the results represent the properties of argon and nitrogen, respectively, at 84°K. The equation of state employed here is the Reiss–Frisch–Lebowitz equation of state for a hard‐sphere fluid, on which is superimposed a van der Waals interaction term. The agreement between our values of the surface tension and the experimental values is satisfactory considering the limitations imposed by the model. The results are compared with those of earlier works.

Statistical‐Mechanical Calculation of Surface Properties of Simple Liquids and Liquid Mixtures. II. Mixtures

Igor W. Plesner, Ole Platz, and S. E. Christiansen

J. Chem. Phys. 48, 5364 (1968); http://dx.doi.org/10.1063/1.1668230 (7 pages) | Cited 11 times

Online Publication Date: 5 September 2003

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Calculation of density transition curves and surface tension in a series of mixtures of argon and nitrogen at 84°K are presented. The densities of the two components as a function of position in the interface furnish insight in the structure of the transition region and predict certain features in regard to the (excess) surface tension, which are confirmed experimentally. The calculated values of surface tension as a function of liquid mole fraction are in satisfactory agreement with experiment. Certain problems pertaining to the numerical solution of simultaneous nonlinear integral equations are discussed.

Polymer Dynamics. IV. The Zero‐Frequency Intrinsic Viscosity of Polymer Molecules with Hydrodynamic Interaction and Excluded Volume

J. E. Hearst, E. Beals, and R. A. Harris

J. Chem. Phys. 48, 5371 (1968); http://dx.doi.org/10.1063/1.1668231 (7 pages) | Cited 17 times

Online Publication Date: 5 September 2003

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The theory and model of Harris and Hearst has been extended to approximately include the effect of hydrodynamic interaction and excluded volume. The results agree in both the coil and rigid‐rod limits with existing theories and experiment. The absence of a linear dependence of [η] upon an appropriate power of the molecular weight introduces some doubt as to the validity of conventional methods of interpretation of viscosity data.

Reaction of H2 + D2⇆2HD Catalyzed by Molybdenum and Observed by Mass Spectrometer

George E. Moore and F. C. Unterwald

J. Chem. Phys. 48, 5378 (1968); http://dx.doi.org/10.1063/1.1668232 (15 pages) | Cited 4 times

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Papers I, II, and III of this series emphasize chemical reactions of the same designation. I describes H2–D2 exchange, II describes 28N2–30N2 exchange, and III reports some measurements on ammonia synthesis. All reactions were catalyzed by the same Mo ribbon. I and II are simpler than III and their study facilitates understanding III. Publications for I show a trend toward the expected equilibrium, but evaluation of catalytic effectiveness usually involved many sorptions of each reactant molecule with the heated catalyst. Our technique permits evaluation resulting from a single sorption interaction and shows for I that sorbed molecules leave our catalyst S at relative abundances agreeing with the equilibrium constant K of the exchange reaction. This equilibration during a single interaction occurs throughout the experimentally accessible temperature range 335°K to above 1000°K and for covers between 0.05 and approximately a complete monolayer. Contamination by nitrogen and by CO does not affect equilibration. Results imply that the catalyst splits the reactant molecules at least intermittently and may suggest atomic, rather than molecular sorption. However, published experiments warn against complete acceptance of atomic sorption. If exchange reactions involve only the catalyst surface, as generally thought, relative departure rates for H2, D2 and HD molecules would satisfy the usual conservation relation calculated from incidence rates from the gas phase onto the catalyst. This relation is independent of K but, with K, would completely specify relative desorption rates of the three molecular forms of hydrogen. Experimentally, only K is satisfied. Desorption rates are not directly related to incidence rates and are only understood if much of the hydrogen and deuterium participating in exchange comes from a phase dissolved in the catalyst, rather than from an adsorbed layer. This and other results suggest that H2–D2 exchange is related more critically to the volume of the catalyst than to its surface. If such results occur for other catalysts and other reactions, widely accepted models for catalysis must be reconsidered.

Interaction of Nitrogen with Mo and the Reaction 28N2 + 30N2⇆229N2 Catalyzed by Mo and Observed by Mass Spectrometer

George E. Moore and F. C. Unterwald

J. Chem. Phys. 48, 5393 (1968); http://dx.doi.org/10.1063/1.1668233 (16 pages) | Cited 4 times

Online Publication Date: 5 September 2003

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This paper describes interactions between N2 and a Mo catalyst, believed significant for synthesis of ammonia. These interactions were sorption, desorption, and isotopic exchange using the same ribbon filament catalyst S as for exchange in hydrogen and for ammonia synthesis; it had previously been used for thermal dissociation of H2. Nitrogen dissolves in S at all temperatures significant for NH3 synthesis. Below 1000°K it also forms the nitride. 30N2 was used where possible to avoid mass ambiguity with CO. 14N and 15N compete in sorption, both on the surface and interior. During the exchange, the three molecular nitrogens desorb from S in equilibrated abundances at all accessible temperatures (T's) and covers. However, accessible T is limited on the low side because: (a) Nitrogen binds so tightly to Mo that puffs adequate for measurement will not desorb below 1000°K. (b) CO, which was not resolved from 28N2, is less tightly bound; it causes significant error in measuring convenient sized 28N2 puffs, unless T during sorption is sufficiently high to eliminate CO. Even more clearly than for exchange in hydrogen, nitrogen exchange by Mo brings into serious question tacit assumptions in much recent published work on adsorption and catalysis. These assumptions consider that all interactions occur on the surface of the catalyst (or adsorbent). For N2 exchange by Mo, diffusion into S was fully as decisive as for hydrogen exchange. Most published experiments employ an ionization gauge to measure pressure changes and also assume, without chemical identification, that pressure changes observed are caused entirely by gas intentionally admitted. Neglect of chemical identification may be responsible for failure to observe volume diffusion effects in recent literature. The measured probability for sorption per collision of N2 on Mo was 0.14 ± 0.04, which is considerably below values previously published.

Tests of Mechanism for Ammonia Synthesis by a Molybdenum Catalyst at Very Low Pressure

George E. Moore and F. C. Unterwald

J. Chem. Phys. 48, 5409 (1968); http://dx.doi.org/10.1063/1.1668234 (23 pages) | Cited 4 times

Online Publication Date: 5 September 2003

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Ammonia has long been synthesized commercially on supported iron catalysts, of complex nature not well understood. Authors usually imply that catalysis occurs on the surface and involves four distinct steps: (1) gaseous N2 and H2 adsorb as atoms; (2) one or both species scurry over the surface as a two‐dimensional gas; (3) atomic collisions in this phase form the radicals NH and NH2; (4) these radicals collide with adsorbed hydrogen molecules or atoms to form NH3 which then evaporates. Published experimental evidence for this plausible mechanism is not strong. Present experiments used a metallic molybdenum catalyst, S, under idealized conditions and suggest modifications. S synthesized ammonia only after long induction during which all nitrogen reactant was 28N2. After synthesis began, it was very persistent, but an additional long induction period was required before S could utilize 30N2 to synthesize ammonia. The interior walls also synthesized ammonia but required even longer induction periods. These and other results show that both reactants must penetrate into S before synthesis occurs. Because Papers I and II showed that S split interacting H2 and N2 molecules, successive formation of NH, NH2, and NH3 seems very probable, but one or more of the key precesses apparently occur inside S, rather than on its surface. Formation of NH could well be one key process. Few NH radicals desorbed, possibly because of strong sorption or short life. NH2 desorbed as such but always less abundantly than NH3. ND4 and ND3H occurred but molecules with four hydrogens were always sparse or absent. H2, as such, readily desorbed at low T's, whether N2 was present or not and it also dissolved in S. Ammonia desorbed about as readily. However nitrogen was very tightly bound and dissolved readily, but it desorbed at low T's only as ammonia or amide. Production of ammonia in our experiment requires a considerably more important role for this catalyst than any apparently reported previously. Catalysts presumably merely activate reactant molecules so that they can experimentally achieve an equilibrium already favored thermodynamically at the pressure–temperature conditions of the gaseous reactants; Reactions (I) and (II) are certainly consistent with this conventional role. However, we produced ammonia at pressures much higher than permitted by free‐energy calculations for the purely homogeneous gaseous reaction. Production of ammonia at the high observed concentrations therefore implies that the reactants, during their interaction with this catalyst, are in a form equivalent to much higher pressure than in their gaseous phase. The observed stability of the resulting gaseous ammonia after it leaves the catalyst need not surprise, because historic experiments long ago established its stability under very unfavorable thermodynamics. Once the reactants properly impregnate S (or the walls) they tend very strongly to desorb as ammonia, rather than as the separate reactants, although the reactants would be strongly favored thermodynamically. Careful chemical identification of catalytic products was especially necessary when thermodynamic conditions were so unfavorable for synthesis but the designations stated were thoroughly established. D2 and 30N2 as reactants helped in chemical identification and in suggesting mechanisms. Mass spectrometers require pressures less than 10−9 those of commercial synthesis. This, and the complexity of commercial catalysts may limit the relevance of our work for practical synthesis.

Momentum and Temperature‐Slip Coefficients with Arbitrary Accommodation at the Surface

S. K. Loyalka

J. Chem. Phys. 48, 5432 (1968); http://dx.doi.org/10.1063/1.1668235 (5 pages) | Cited 28 times

Online Publication Date: 5 September 2003

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Accurate theoretical expressions for momentum and temperature‐slip coefficients for monatomic gases with arbitrary accommodation at the surface are derived by applying a variational technique to the full linearized Boltzmann equation. In the jump regimes, the use of these expressions appears preferable to the use of the previous results based on mean‐free‐path theory or numerical methods. As an example, a correction in the reported values of accommodation coefficients is suggested.

Absorption and Phosphorescence Spectrum of Matrix‐Isolated Ferrocene

J. J. Smith and Beat Meyer

J. Chem. Phys. 48, 5436 (1968); http://dx.doi.org/10.1063/1.1668236 (4 pages) | Cited 9 times

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The absorption and fluorescence spectrum of ferrocene was studied in argon, krypton, xenon, nitrogen, and methane matrices at 20°K. Five electronic transitions were found in the region from 50 000–16 000 cm−1. The absorption bands appear sharper and the band structure simpler than in the vapor phase or solution. A weak but distinct phosphorescence spectrum was recorded, the lifetime of which varied between 1 and 4 sec in different matrices.

Excimer Emission of Naphthalene, Anthracene, and Phenanthrene Crystals Produced by Very High Pressures

Peter F. Jones and Malcolm Nicol

J. Chem. Phys. 48, 5440 (1968); http://dx.doi.org/10.1063/1.1668237 (8 pages) | Cited 27 times

Online Publication Date: 5 September 2003

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Fluorescence spectra of ultrapure crystals of naphthalene, anthracene, and phenanthrene have been studied at pressures as great as 50 kbar. These spectra exhibit complex irreversible effects superimposed upon the expected reversible shifts in the energies of the normal fluorescence spectra. The irreversible effects include a loss of the intensity of the normal fluorescence with increasing pressure and the almost simultaneous appearance of a broad, featureless emission at energies about 3000–6000 cm−1 lower than that of the normal fluorescence. This emission is assigned as the fluorescence of excimers formed upon optical excitation of the crystals under high pressure. The crystals continue to exhibit this excimer fluorescence after the pressure is reduced to atmospheric pressure, but the irreversible effects can be removed by thermal annealing of the crystal at atmospheric pressure. The irreversibility is attributed to trapping of pairs of molecules in an excimer‐like orientation as a crystal defect after they lose the excitation energy of the excimer. These defects then act as traps for excitation energy in the crystal. Other possible interpretations of the irreversible effects are discussed.

Spectral Shifts and Broadening of the Fluorescence of Anthracene and Tetracene in Several Host Crystals at High Pressures

Peter F. Jones

J. Chem. Phys. 48, 5448 (1968); http://dx.doi.org/10.1063/1.1668238 (9 pages) | Cited 13 times

Online Publication Date: 5 September 2003

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The fluorescence spectra of anthracene in biphenyl, p‐terphenyl, naphthalene, and phenanthrene and those of tetracene in p‐terphenyl, naphthalene, phenanthrene, and anthracene were measured at pressures as great as 50 kbar. The pressure effects on the spectra of the guests are generally analogous to the pressure effects in solution or the gas phase. Due to the increased dispersion interaction between these nonpolar molecules upon compression, the energies of the electronic transitions are shifted toward the red (lower energy), and the spectral bands are broadened, while the integrated intensity remains approximately constant. As the pressure is released, the fluorescence spectra return to those obtained before compression. The spectral shifts with pressure are satisfactorily interpreted in terms of a second‐order perturbation theory using a dipole–dipole approximation. For three of the eight guest–host combinations, the fluorescence spectra above 35 kbar were considerably broader than expected. The similar broadening observed for the pure host crystals suggests that mixed excimers are produced at high pressures. On the basis of the present data, however, it is not possible to give an unambiguous explanation of the extensive broadening.

Fluorescence of Doped Crystals of Anthracene, Naphthalene, and Phenanthrene under High Pressures: The Role of Excimers in Energy Transfer to the Guest Molecules

Peter F. Jones and Malcolm Nicol

J. Chem. Phys. 48, 5457 (1968); http://dx.doi.org/10.1063/1.1668239 (8 pages) | Cited 11 times

Online Publication Date: 5 September 2003

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Fluorescence spectra of crystals of anthracene, naphthalene, and phenanthrene doped with other polycyclic aromatic hydrocarbons have been studied at pressures as great as 50 kbar. The most significant effects of pressure on the spectra of the host crystals are a loss of intensity of the normal fluorescence with increasing pressure and the almost simultaneous appearance of a broad, featureless emission at energies about 3000–6000 cm−1 lower than that of the normal fluorescence. This emission is assigned as the fluorescence of excimers formed upon optical excitation of the crystals under high pressure. The growth of the intensity of the excimer emission with increasing pressure, relative to the intensity of the normal fluorescence, is the same in doped crystals as in pure crystals. The intensities of the guest molecule fluorescence relative to the intensity of the normal host fluorescence in the various doped crystals increase with pressure at about the same rate as the intensity of the excimer emission. These observations are interpreted as indicating that excimers are the lowest‐energy excited singlet species of aromatic molecular crystals at these pressures and that when the excimer concentration is appreciable, the path of energy transfer is from the host via excimers to the guest.

Carbon Characteristic X‐Rays from Gaseous Compounds

R. A. Mattson and R. C. Ehlert

J. Chem. Phys. 48, 5465 (1968); http://dx.doi.org/10.1063/1.1668240 (6 pages) | Cited 33 times

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Carbon spectra from CH4, C2H6, C3H8, C4H10, CCl4, CBr4, CF4, benzene, cyclohexane, ethylene, acetylene, CO, and CO2 have been measured in an ultrasoft x‐ray spectrometer using electron‐beam excitation, a lead stearate multilayer analyzer, and a thin window flow proportional counter. The spectra have been corrected for background and normalized so that the height of the largest peak of each spectra is the same. Similar molecular species exhibit similar spectra. Furthermore, for the alkanes, a correlation is observed between the position of the main peak and the first ionization potential of the molecule.

X‐Ray Emission Spectra from Chlorinated Methanes and Fluorochloromethanes

R. C. Ehlert and R. A. Mattson

J. Chem. Phys. 48, 5471 (1968); http://dx.doi.org/10.1063/1.1668242 (5 pages) | Cited 14 times

Online Publication Date: 5 September 2003

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The carbon K, fluorine K, and chlorine L spectra are presented for the chlorinated methanes (CCl4, CHCl3, CH2Cl2, CH3Cl) and fluorochloromethanes (CFCl3, CF2Cl2, CF3Cl, CHFCl2, CHF2Cl). Comparisons are made with the spectra of methane and carbon tetrafluoride. Multiplet structure is observed in every case. The position and intensity of the various lines is dependent on the type and number of halogens present in the molecule.

Kinetics of Excited Molecules. VI. Energy Transfer from Hexafluoroacetone to Hexafluorobiacetyl

John S. E. McIntosh and Gerald B. Porter

J. Chem. Phys. 48, 5475 (1968); http://dx.doi.org/10.1063/1.1668243 (5 pages) | Cited 1 time

Online Publication Date: 5 September 2003

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In mixtures of hexafluoroacetone and hexafluorobiacetyl, both singlet–singlet and triplet–triplet energy transfer occur. Low pressures of hexafluorobiacetyl quench the phosphorescence of hexafluoroacetone and sensitized phosphorescence of hexafluorobiacetyl appears. The same phenomenon is observed with high pressures of hexafluorobiacetyl with regard to fluorescence quenching and sensitization. The bimolecular rate constants for energy transfer evaluated from these data and from the fluorescence and phosphorescence lifetimes are: 8.5 × 108 liters/mole⋅sec (triplet–triplet) and 6.0×109 liters/mole⋅sec (singlet–singlet).

I. Kinetics of Reactions of Electrons during Radiolysis of Liquid Methanol. II. Reaction of Electrons with Liquid Alcohols and with Water

K. N. Jha and G. R. Freeman

J. Chem. Phys. 48, 5480 (1968); http://dx.doi.org/10.1063/1.1668244 (11 pages) | Cited 8 times

Online Publication Date: 5 September 2003

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The gamma radiolysis of liquid methanol has been studied over the temperature range from its melting point ( − 98°) to its critical temperature (240°). The value of G(H2) varies from 4.95 at −98° to 5.45 at 25° and 8.0 at 240°. Sulfuric acid and nitrous oxide were added as electron scavengers at −97°, 25°, and 150°. The nitrogen and hydrogen yields were calculated as functions of the nitrous oxide concentration at each of the three temperatures. The calculations were based on a proposed mechanism. Homogeneous kinetics were used for the reactions of the free ions and nonhomogeneous kinetics were used for the reactions in spurs. At −97°, G(totalionization)  =  4.6 and the value is assumed to be independent of temperature. The yield of free ions is G(esolv−)fi  =  2.0 ± 0.2, independent of temperature from −97° − 150°. The reaction esolv−→CH3Osolv−) + H has a rate constant of 4.6 × 105 sec− 1 at 25° and an activation energy equal to that of dielectric relaxation (3.7 kcal/mole); the entropy of activation of the reaction is −21 cal/deg⋅mole. In each of the liquids methanol, ethanol, isopropanol, and probably also water, the reaction esolv−→ROsolv− + H has an activation energy approximately equal to that of dielectric relaxation and has a large negative entropy of activation. The large negative entropy of activation indicates that the transition state has a relatively specific structure. It is suggested that solvated electrons are liquid‐structure breakers in water and relatively weak structure formers in the alcohols.

Contributions of Internal Rotation to the Rotational Coefficients in Phenol

C. R. Quade

J. Chem. Phys. 48, 5490 (1968); http://dx.doi.org/10.1063/1.1668245 (4 pages) | Cited 14 times

Online Publication Date: 5 September 2003

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The theory of internal rotation for molecules with twofold barriers is used to calculate the rotational coefficients for phenol using three possible structures. The difference in coefficients for the substates of the ground torsional state is found to be quite dependent upon the structure of the hydroxyl group. Structural parameters for the hydroxyl group are obtained which are consistent with the observed splittings of the microwave rotational spectra.

Euler‐Angle Reduction of the Schrödinger Equation for Three‐Electron Atoms

T. Kalotas, M. H. Lloyd, and L. M. Delves

J. Chem. Phys. 48, 5494 (1968); http://dx.doi.org/10.1063/1.1668246 (9 pages) | Cited 4 times

Online Publication Date: 5 September 2003

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A correction is given to a recent Euler‐angle classification of the states of three‐electron atoms. The non‐relativistic Schrödinger equation for these states is written in terms of the Euler‐angle coordinates and the spin–Euler‐angle integrations carried out explicitly for a state of arbitrary (J,π).
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