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15 Aug 1972

Volume 57, Issue 4, pp. 1369-1814

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Vibrational and Other Corrections to the Nuclear Quadrupole Moment of 14N in Ammonia

P. Grigolini and R. Moccia

J. Chem. Phys. 57, 1369 (1972); http://dx.doi.org/10.1063/1.1678412 (8 pages) | Cited 17 times

Online Publication Date: 3 September 2003

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The field gradient at the nitrogen nucleus has been evaluated for the NH3 molecule using two different rather accurate electronic molecular wavefunctions. The vibrational correction has been obtained by averaging the field gradient for the two totally symmetric vibrations of the C3v point group computed at a number of geometrical configurations. In addition, a careful analysis has been carried out to assess the effect of the electronic quadrupole polarization and other higher order effects. The value for the nuclear quadrupole moment of 14N in ammonia so obtained is 2.16×10−26 cm2.

Kinetics of the Reaction of O(3P) Atoms with Benzene

Richard A. Bonanno, Poonzag Kim, Jai‐Hoon Lee, and Richard B. Timmons

J. Chem. Phys. 57, 1377 (1972); http://dx.doi.org/10.1063/1.1678413 (4 pages) | Cited 19 times

Online Publication Date: 3 September 2003

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The kinetics of the gas phase reaction of O(3P) atoms with benzene was investigated using fast flow techniques. Specific rate constants were obtained using two separate systems, one with ESR detection to monitor the decrease in O(3P) atoms and the other with mass spectrometry to follow the change in benzene concentration. The rate constant computed with respect to O(3P) removal is much larger than that obtained in the mass spectrometer studies and this is believed to result from further reactions of oxygen atoms with radical species produced in the initial O(3P)+C6H6 interaction. On the basis of the mass spectrometric studies a specific rate constant for the reaction
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of (3.8±1.5)×1013 exp(−4,400±500/RT) cm3 mole−1⋅sec−1 was obtained over the temperature range of 255–305°K. A negligibly small kinetic isotope effect was observed in competitive experiments with C6H6 and C6D6. The results obtained are interpreted in terms of a rate determining step involving the addition of oxygen atoms to the benzene ring followed by subsequent isomerization and∕or decomposition reactions.

Influence of Surface Charge and Surface Structure on the Sublimation of Ionic Crystals

D. W. Short, R. A. Rapp, and J. P. Hirth

J. Chem. Phys. 57, 1381 (1972); http://dx.doi.org/10.1063/1.1678414 (12 pages) | Cited 14 times

Online Publication Date: 3 September 2003

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The formation of charged defects in ionic crystals is shown to be accompanied by the formation of surface defects: kinks. The resultant defect pairs contribute to a Debye‐Hückel charge distribution at the surface. Surface charge, surface structure, and crystal defect equilibria are found to be interrelated and to influence sublimation rates. The theory is applied to the case of sublimation of II‐VI compounds and compared with experiments.

Quantum Mechanical Scattering of Asymmetric Molecules. II. Comparison between the Systems He☒D2 and He☒HT

W. F. Heukels and J. van de Ree

J. Chem. Phys. 57, 1393 (1972); http://dx.doi.org/10.1063/1.1678415 (7 pages) | Cited 13 times

Online Publication Date: 3 September 2003

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Exact quantum mechanical coupled channel calculations have been performed in order to compare the rotating potential model for heteronuclear molecules with an asymmetric mass distribution, and the usual potential with anisotropy terms for homonuclear molecules. The scattering cross sections of He☒D2 and He☒HT show no difference in shape, apart from some quenching of the orbiting resonances. There is, however, a significant difference in absolute magnitude, due predominantly to inelastic processes. In the inelastic cross sections, the effect of the shift of the center of mass from the center of interaction in asymmetric molecules counteracts the effect of a change in moment of inertia.

Elastic Constants of the Nematic Liquid Crystalline Phase of p‐Methoxybenzylidene‐p‐n‐Butylaniline (MBBA)

Ivan Haller

J. Chem. Phys. 57, 1400 (1972); http://dx.doi.org/10.1063/1.1678416 (6 pages) | Cited 137 times

Online Publication Date: 3 September 2003

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The bend and splay elastic constants of MBBA were measured over its nematic temperature range. The ratio of the two constants is 1.25±0.05. The temperature dependence of the elastic constants is found to be adequately described by the simple mean‐field models. A comparison is made between viscosity coefficients obtained from the elastic constants and light scattering spectra and from classical viscosity measurements. A method proposed for the measurement of twist elastic constants is evaluated and an upper limit of this constant of MBBA as a function of temperature is reported.

Scattering by an r−2n Potential in the Born Approximation and Application to Dipole‐Quadrupole Scattering

P. S. Ganas

J. Chem. Phys. 57, 1406 (1972); http://dx.doi.org/10.1063/1.1678417 (2 pages) | Cited 1 time

Online Publication Date: 3 September 2003

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By using the Born approximation, an analytic formula is derived for the phase shifts δL for scattering by a potential with an r−2n tail. The low‐energy properties of the phase shifts are discussed, and an expansion of tan δL in powers of k is presented. The dipole‐quadrupole r−8 potential is discussed as a special case.

Effect of Pressure on the Rates of Reaction of Solvated Electrons in Liquid Ethanol

Kamal N. Jha and Gordon R. Freeman

J. Chem. Phys. 57, 1408 (1972); http://dx.doi.org/10.1063/1.1678418 (7 pages) | Cited 3 times

Online Publication Date: 3 September 2003

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At a γ radiolysis dose of 1×1018 eV/g in ethanol at 296°K the hydrogen yields in neutral ethanol were G(H2) = 5.0 at 1 bar and 5.5 at 5.3 kbar; in 1 mM and 1 M sulfuric acid G(H2) = 5.7, independent of pressure. The electron scavengers nitrobenzene, acetone, and naphthalene reduce the hydrogen yields in neutral and acidic ethanol at 1 bar and 5.3 kbar; increasing the pressure greatly reduces the ease of scavenging the free ions but has only a small effect on scavenging efficiency in the spurs. Using as a standard the reaction esolv−→C2H5Osolv−+H with k = 1.2×105 sec−1 at 1 bar and ΔV‡ = −14.4 cm2/mole averaged between 0 and 5.3 kbar, one obtains the following values for k(M−1⋅sec−1) and ΔV‡ (cm3/mole):esolv−+Hsolv+, 2.8×1010 at zero ionic strength, +4.5; esolv−+C6H5NO2, 1.5×1010, +7.5; esolv−+naphthalene, 5.0×109, +5.6; esolv−+CH3COCH3, 4.2×109, +5.1. The diffusion coefficient of solvated electrons in ethanol appears to correlate with the liquid viscosity; this is different from the behavior of electrons in alkanes. In ethanol ΔV‡diffusion ≈ +7 cm3/mole for esolv− and +4 cm3/mole for Hsolv+. The free ion yield in ethanol is G(esolv−)fi = 1.7, independent of pressure from 1 bar to 5.3 kbar; the model of Freeman and Fayadh [J. Chem. Phys. 43, 86 (1965)] is consistent with this behavior and it predicts that Gfi in methanol and water are also independent of pressure.

Laser Raman Spectra of Solid and Molten NaNH2: Evidence for Hindered Rotation of the NH2−1 Ion

Paul T. Cunningham and Victor A. Maroni

J. Chem. Phys. 57, 1415 (1972); http://dx.doi.org/10.1063/1.1678419 (4 pages)

Online Publication Date: 3 September 2003

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Results of a Raman study of solid and molten NaNH2 (mp ≃ 211°C) from 25–220°C are reported. Three bands are observed in both the solid (3267, 3218, and 1531 cm−1) and the liquid (3267 dp, 3218 p, and 1550 p cm−1), which are assigned to the three expected fundamental modes of NH2−1 with C2v point symmetry. Additional bands were observed in the 300–700 cm−1 region for both the solid and the liquid. In the case of the liquid, the band envelope in this region was resolved into three Gaussian components, which are attributed to the hindered rotational modes of NH2−. There was no evidence of intermolecular hydrogen bonding between NH2− ions.

Studies of the Triplet State of Carbonyl Compounds. I. Phosphorescence of β‐Diketones

P. Gacoin

J. Chem. Phys. 57, 1418 (1972); http://dx.doi.org/10.1063/1.1678420 (8 pages) | Cited 4 times

Online Publication Date: 3 September 2003

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The phosphorescence intensity of the diketone form and of one of the two chelated enol forms of β‐diketones in solution at 77°K depends largely on the solvent used. The phosphorescence of the diketone form (seen principally in polar solvent) is similar to that of aromatic monoketones and arises from a Tnπ* state. The phosphorescence of one of the two chelated enol forms in nonpolar solvent is emitted from a Tππ* state as suggested by the external and internal heavy atom effects. However the shortness of the phosphorescence lifetime shows that the lowest triplet state is probably mixed with some higher energy triplet state of nπ* type. The diketone form seems much more luminescent than the chelated enol form. This result is consistent with the suggestion of Lamola [A. A. Lamola and L. J. Sharp, J. Phys. Chem. 70, 2634 (1966)] that a very fast radiationless decay takes place in molecules possessing an intramolecular hydrogen bond between the carbonyl oxygen and the hydroxyl hydrogen. The comparison of chelated enol spectra with those of crotonophenone and benzalacetone indicates that phosphorescent chelated enol has structure II, the other form being nonradiatively deactivated or nonexistent. Benzoyltrifluoroacetone gives a spectrum with a long lifetime which seems to originate from a nonchelated enol form.

Torsional Barriers in the Methyl Substituted Ethylenes

J. R. Durig, C. W. Hawley, and J. Bragin

J. Chem. Phys. 57, 1426 (1972); http://dx.doi.org/10.1063/1.1678421 (10 pages) | Cited 14 times

Online Publication Date: 3 September 2003

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The far‐infrared spectra have been recorded from 350 to 33 cm−1 for propene, cis‐2‐butene, trans‐2‐butene, isobutene, 2‐methyl‐2‐butene, and 2,3‐dimethyl‐2‐butene, in the gaseous and solid states (−190°C). The Raman spectra of the liquids have also been recorded in the same frequency range. The bands corresponding to the torsional modes are assigned as appearing at 226; 195; 233 and 219; 183 and 144; 219 and 178; and 227, 201, 194, and 153 cm−1, in the infrared spectra of propene, trans‐2‐butene, isobutene, cis‐2‐butene, 2‐methyl‐2‐butene, and 2,3‐dimethyl‐2‐butene, respectively, in the solid state. The corresponding barriers to internal rotation are 2.68, 2.21, 3.24, 1.82, 2.45, and 2.25 kcal∕mole.

On the Coupling Scheme in Uranyl Complexes

C. Görller‐Walrand and L. G. Vanquickenborne

J. Chem. Phys. 57, 1436 (1972); http://dx.doi.org/10.1063/1.1678422 (5 pages) | Cited 15 times

Online Publication Date: 3 September 2003

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Simple theoretical considerations of the ligand field type have been applied to the electronic structure of insular uranyl complexes. The study of the consequences of equatorial ligation is used as a means to test the applicability of different coupling schemes for the isolated uranyl ion. From the analysis of the spectra of a large number of different uranyl complexes of Dnh symmetry, it was previously shown how the effect of equatorial ligation consists in lifting certain degeneracies of the free uranyl electronic energy levels and introducing variations in the corresponding transition probabilities. In this note the equatorial field operator is successively applied to uranyl wavefunctions derived in a Russell‐Saunders approximation, in an ω‐ω coupling approximation, and in an intermediate scheme. Only Russell‐Saunders coupling allows a satisfactory explanation of the observed splitting and intensity pattern.

Kinetic Theory of Droplet Growth in Nucleation

G. E. Kelly and J. V. Sengers

J. Chem. Phys. 57, 1441 (1972); http://dx.doi.org/10.1063/1.1678423 (18 pages) | Cited 8 times

Online Publication Date: 3 September 2003

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A kinetic theory is presented for the mass flux to a liquid droplet surrounded by its pure vapor. When the mass flux Γ is expanded in terms of a parameter α which is the ratio of the droplet size to the mean free path (inverse Knudsen number), one obtains a series of the form Γ = Γ(0)+Γ(1)α+math(2)α2 lnα+⋅⋅⋅. The coefficients of the first three terms of this expansion are derived by solving the Boltzmann equation using a modified Knudsen number iteration procedure. It is shown that the coefficients are determined by integrals associated with sequences of successive collisions among a number of vapor molecules and the droplet. These collision integrals bear a close similarity to the collision integrals derived earlier from the generalized Boltzmann equation for the density dependence of the transport properties of gases.

Reactions of NO2− and NO3− with HCl and HBr

E. E. Ferguson, D. B. Dunkin, and F. C. Fehsenfeld

J. Chem. Phys. 57, 1459 (1972); http://dx.doi.org/10.1063/1.1678424 (5 pages) | Cited 23 times

Online Publication Date: 3 September 2003

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Reactions of NO2− and NO3− with HCl and HBr were carried out in a flowing afterglow system at room temperature and the reaction rate constants were measured. The reaction NO3−+HBr→Br−+HNO3 is found to be nearly thermoneutral. The results lead to these values of electron affinities: E.A.(NO2)<2.6 eV,E.A.(NO3) = 3.9±0.2 eV. In addition, rate constants for the reactions of NO− and O2− with HCl are reported. A number of cluster ions were observed: NO3−(HCl)1,2,NO3−(HNO3)1,2,NO3−⋅HNO3(HCl)1,2, and Br− (HNO3)1,2.

Thin Film Reflection Spectroscopy. I. Determination of Optical Constants of Amorphous Selenium and As2Se3

Jan Bock and Gouq Jen Su

J. Chem. Phys. 57, 1464 (1972); http://dx.doi.org/10.1063/1.1678425 (9 pages)

Online Publication Date: 3 September 2003

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The reflectivity spectra of thin films of amorphous As2Se3 and Se have been obtained. The films were deposited on aluminum substrates and had a range of thickness from 2 to 50 μ. The frequency range covered by these spectra was from 650 to 40 wavenumbers (15 to 250 μ). Two methods have been used to determine the optical constants, N and K, from the reflectivity spectra. The first employs a single equation nonlinear regression analysis on the radiant reflectance equation. The second method uses a two equation maximum likelihood analysis on the real and imaginary parts of the amplitude reflectance equation coupled with a Kramers‐Kronig analysis of the phase angle. The real and imaginary parts of the complex dielectric constant, the absorption coefficient, the energy loss function and the transverse and longitudinal vibrational frequencies are then determined from the optical constants.

Pressure Dependence of Energy Transfer from Pyrene to Perylene

P. C. Johnson and H. W. Offen

J. Chem. Phys. 57, 1473 (1972); http://dx.doi.org/10.1063/1.1678426 (3 pages) | Cited 1 time

Online Publication Date: 3 September 2003

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The efficiency of singlet‐singlet energy transfer between pyrene and perylene in polymethylmethacrylate decreases with increasing pressure, i.e., at 77°K the critical transfer distance R0 is 44 Å at 1 atm and 35 Å at 30 kbar. The factors responsible for the reduced efficiency at high pressure are in order of decreasing importance: the decrease in the fluorescence lifetime of the donor, the increase in the refractive index of the medium, and the decrease in spectral overlap of pyrene fluorescence and perylene absorption.

Thermodynamics of Rare‐Earth‐Carbon Systems. IV. The Lutetium‐Carbon System

M. Guido, G. Balducci, and G. De Maria

J. Chem. Phys. 57, 1475 (1972); http://dx.doi.org/10.1063/1.1678427 (5 pages) | Cited 5 times

Online Publication Date: 3 September 2003

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The vaporization of the lutetium dicarbide‐carbon system has been investigated by the Knudsen effusion‐mass spectrometric technique over the temperature range 2100 to 2600°K. Lu(g) partial pressures, dissociation energies for LuC2(g) and LuC4(g) molecules, and the standard heat of formation for LuC2(s) were obtained.

Correlation Functions for a Mixture of Gaussian Molecules

Eugene Helfand and Zelda Wasserman

J. Chem. Phys. 57, 1480 (1972); http://dx.doi.org/10.1063/1.1678428 (7 pages) | Cited 1 time

Online Publication Date: 3 September 2003

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The Mayer series for the pair correlation functions of the Gaussian mixture has been determined to ninth power of the density (11‐point graphs). The model is a mixture of A and B in which the AA and BB interaction potentials are zero. The AB interaction is such that the Mayer f function, exp (−vAB∕kBT) −1, is a negative Gaussian. The direct correlation functions and radial distribution functions are evaluated using Padé approximants. Comparison is made with solutions of the Percus‐Yevick and hypernetted chain equations.

Molecular Beam Electric Deflection and Resonance Spectroscopy of the Heteronuclear Alkali Dimers: 39K7Li, Rb7Li, 39K23Na, Rb23Na, and 133Cs23Na

Paul J. Dagdigian and Lennard Wharton

J. Chem. Phys. 57, 1487 (1972); http://dx.doi.org/10.1063/1.1678429 (10 pages) | Cited 36 times

Online Publication Date: 3 September 2003

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Molecular beam electric resonance spectra for several heteronuclear alkali dimers have been obtained for the ∣MJ∣ = 0→1 transition in the J = 1, v=0 state in a supersonic beam. Values of the ground vibronic Stark coefficient μ02/B0 and the nuclear quadrupole coupling constants eqQ were obtained. The values of μ02/B0 were (2.269±0.002)×10−19 cm3 for 39K7Li, (3.697±0.004)×10−19 cm3 for 85Rb7Li, and (3.966±0.004)×10−18 cm3 for 39K23Na. Badger's rule was used to estimate B0 and to determine the following values for the molecular electric dipole moment: μ0(39K7Li) = 3.45±0.1 D,μ0(85Rb7Li) = 4.00±0.1 D, and μ0(39K23Na) = 2.76±0.1 D, where the errors arise from the uncertainties in the rotational constant. Electric deflection was used to obtain a value of μ2∕B for Rb23Na of (6.6±0.5)×10−19 cm3 and hence 3.1±0.3 D for the dipole moment, while rf spectroscopy with power broadening was employed with 133Cs23Na to obtain (1.81±0.02)×10−18 cm3 for μ02/B0 and hence 4.75±0.2 D for μ0. The translational and rotational temperatures in the supersonic beams were estimated from velocity scans and quadrupole voltage scans. An ionic model is used in a heuristic interpretation of the dipole moment results.

Effects of Screening and Polarization on Vibration‐Rotation Properties of H2

Stuart F. Hayes and Charles L. Beckel

J. Chem. Phys. 57, 1497 (1972); http://dx.doi.org/10.1063/1.1678430 (6 pages) | Cited 3 times

Online Publication Date: 3 September 2003

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Eight simple models of H2 in the ground state are examined through use of Dunham's formulas, numerical integration of the vibrational Schrödinger equation, and the WBK energy condition. These models provide four examples for studying the effects of variable screening and four examples for the effects of polarization on vibration‐rotation properties. At small v, variability of the screening parameter α correlates with positive curvatures of the ΔG and Bv curves; i.e., for the four models with α = 1 both curvatures are negative, while both curvatures are positive for the four cases with α variable. The dominance of the quartic potential coefficient a2 in determining near‐equilibrium ΔG and Bv curvatures is pointed out. Near dissociation, the presence of polarization causes positive curvature of these two curves. In showing this, large fictitious values of the reduced mass are employed to provide several vibrational levels very close to the dissociation limit. The Dv curves have a pronounced minimum, similar to that of the experimental curve, for α variable but not for α = 1. In addition, the values of Dv and Hv are much closer to experiment for α variable than for α = 1.

Manifestations of Anharmonicity in the Specific Heat of Crystalline 63Cu

T. F. Stromberg, R. J. Balestri, and W. C. Overton

J. Chem. Phys. 57, 1502 (1972); http://dx.doi.org/10.1063/1.1678431 (13 pages) | Cited 2 times

Online Publication Date: 3 September 2003

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Accurate measurements of the specific heat of a high purity single crystal of 63Cu have been carried out for T<50°K. The data are analyzed in terms of deviations from the specific heat of a physically realistic phonon model for 63Cu. The sixth neighbor general‐force model determined for normal Cu at 49°K by neutron diffraction measurements has been adapted to 63Cu by a scaling method. Precision calculations of phonon spectra were done for both general‐force and simple Leighton models. A statistical analysis shows deviation curve features are statistically significant with a minimum close to that of the theoretical quartic anharmonic contribution. Smoothed experimental Cp and Cv data are given for crystalline 63Cu.

Dissociation of Molecular Ions Formed by Charge Exchange in an In‐Line Tandem Mass Spectrometer

C. Lifshitz and T. O. Tiernan

J. Chem. Phys. 57, 1515 (1972); http://dx.doi.org/10.1063/1.1678432 (20 pages) | Cited 7 times

Online Publication Date: 3 September 2003

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Dissociations of the molecular ions of several alkanes, alcohols, and ketones, formed in charge‐exchange collisions were studied using an in‐line tandem mass spectrometer. The effects of both incident ion translational energy and collision chamber temperature upon the observed dissociations were examined. For most of the molecules investigated, the extent of fragmentation of the molecular ion increases as the kinetic energy is raised, indicating that energy is being converted from the translational modes into target excitation. The magnitude of this energy conversion seems to be rather small. Higher collision chamber temperatures also lead to more extensive fragmentation, presumably owing to increased vibrational excitation. In certain cases, notably methanol and 2‐hexanone, an increase in the translational energy of incident ions having recombination energies near the onset of known excited ionic states of these molecules results in an increase in the relative intensity of the molecular ion product. This is interpreted as indicating the formation of long‐lived excited electronic states of the molecular ion which do not revert to the ground state via radiationless transitions. Charge‐exchange spectra obtained in the present study are compared with breakdown graphs previously determined from similar experiments in perpendicular‐type tandem mass spectrometers, and also with the results of photoionization experiments and calculations based on the quasiequilibrium theory.

Vibrational Spectra of the Mercuric Halides Associated with Dioxane and Benzene

T. B. Brill

J. Chem. Phys. 57, 1534 (1972); http://dx.doi.org/10.1063/1.1678433 (3 pages) | Cited 9 times

Online Publication Date: 3 September 2003

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Far ir and Raman measurements of the mercuric halides dissolved in dioxane and benzene along with solid state HgX2‐dioxane data are reported. Dipole moment measurements have suggested that the mercuric halides dissolved in dioxane and benzene are either bent with angles between 140°–160° or have a charge transfer of 0.07–0.15 electrons from the donor to the acceptor molecule. The vibrational spectra here suggest that the HgX2 retains near linearity, the X☒Hg☒X angle probably being greater than 175°, and that the amount of charge transfer is not unusually large.

Translational Diffusion Coefficients of Rodlike Polymers: Application of the Modified Oseen Tensor

Hiromi Yamakawa and Genzo Tanaka

J. Chem. Phys. 57, 1537 (1972); http://dx.doi.org/10.1063/1.1678434 (6 pages) | Cited 18 times

Online Publication Date: 3 September 2003

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The translational diffusion coefficient of a rodlike polymer is investigated in the Kirkwood‐Riseman scheme with the use of the modified Oseen tensor derived previously by Yamakawa for the finite bead model. If it is assumed that the friction coefficient of the beads may be described by Stokes' law, this tensor can remove the Zwanzig singularities from the possible range of the strength of the hydrodynamic interaction. It is pointed out that the preaveraging of the Oseen tensor may remove the singularities apparently in some cases. The correct asymptotic solution is also obtained without transforming a set of simultaneous equations determining the frictional forces to an integral equation. The results show that the finite bead model of a rodlike polymer is intermediate between the ellipsoid and cylinder models in transport behavior.

Translational Diffusion Coefficients of Plane‐Polygonal Polymers: Application of the Modified Oseen Tensor

Hiromi Yamakawa and Jun‐ichi Yamaki

J. Chem. Phys. 57, 1542 (1972); http://dx.doi.org/10.1063/1.1678435 (5 pages) | Cited 11 times

Online Publication Date: 3 September 2003

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The translational diffusion coefficient of a plane‐polygonal polymer is investigated in the Kirkwood‐Riseman scheme following the procedure of Paul and Mazo with the use of the modified Oseen tensor for the finite bead model. Required summations over indices are exactly carried out with the aid of a digital computer. It is pointed out that the mathematical singularities or zeroes can occur in both cases of the Oseen tensor and the modified Oseen tensor, but never appear within the physically possible range of the strength of the hydrodynamic interaction if the beads are assumed to obey Stokes' law. The correct asymptotic solution is also obtained and the results are compared with those for a continuous rigid ring.

Energy Distribution Among Reaction Products. IV. X+HY (X ≡ Cl, Br; Y ≡ Br, I), Cl+DI

D. H. Maylotte, J. C. Polanyi, and K. B. Woodall

J. Chem. Phys. 57, 1547 (1972); http://dx.doi.org/10.1063/1.1678436 (14 pages) | Cited 139 times

Online Publication Date: 3 September 2003

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The distribution of vibrational, rotational, and translational energies (symbolized by V′, R′, and T′) have been obtained for the products of the isotopic pair of reactions Cl+HI→HCl+I and Cl+DI→DCl+I. The experimental method was the ``arrested relaxation'' variant of the infrared chemiluminescence technique. Detailed rate constants k(V′, R′, T′) are reported in the form of contour plots for these reactions. The total detailed rate constants into specified vibrational quantum states for Cl+HI (summed over the rotational levels of each v′ level) are k(v′ = 1) = 0.22, k(v′ = 2) = 0.35, [k(v′ = 3) = 1.00], k(v′ = 4) = 0.74; and for Cl+DI, k(v′ = 1) ≈ 0.08, k(v′ = 2) = 0.14, k(v′ = 3) = 0.35, k(v′ = 4) = 0.73, [k(v′ = 5) = 1.00], k(v′ = 6) = 0.05 [relative to the highest rate constant k(v′) = 1.00, in each case]. Preliminary energy distributions are also reported for the products of two other reactions, Cl+HBr→HCl+Br and Br+HI→HBr+I, in the X+HY→HX+Y family (X and Y are halogen atoms). The members of this family of reactions channel a substantial fraction of the energy available to the products into vibrational and rotational excitation, and only a small fraction into relative translation. For the Cl+HI and also the Cl+DI reaction the fractions are mathV′+mathR′( = 0.71+0.13) = 0.84; in contrast to mathT′ = 0.16. As a corollary there is a marked inverse correlation between vibrational and rotational excitation in the reaction products. Despite the fact that the detailed rate constants into specified product quantum states [k(v′, J′)] are markedly different for the isotopic pair of reactions, the fractional conversion of the available energy into vibration, rotation, and translation are in close agreement (to ∼ ±1%). This close parallelism in fV′, fR′, fT′ is in accord with predictions from classical trajectory studies. It indicates the usefulness of such calculations even for the case of reactions which yield products with widely spaced (vibrational and rotational) quantum levels.
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