Showing papers in "Journal of Chemical Physics in 1971"
TL;DR: In this article, an extended basis set of atomic functions expressed as fixed linear combinations of Gaussian functions is presented for hydrogen and the first row atoms carbon to fluorine, where each inner shell is represented by a single basis function taken as a sum of four Gaussians and each valence orbital is split into inner and outer parts described by three and one Gaussian function, respectively.
Abstract: An extended basis set of atomic functions expressed as fixed linear combinations of Gaussian functions is presented for hydrogen and the first‐row atoms carbon to fluorine. In this set, described as 4–31 G, each inner shell is represented by a single basis function taken as a sum of four Gaussians and each valence orbital is split into inner and outer parts described by three and one Gaussian function, respectively. The expansion coefficients and Gaussian exponents are determined by minimizing the total calculated energy of the atomic ground state. This basis set is then used in single‐determinant molecular‐orbital studies of a group of small polyatomic molecules. Optimization of valence‐shell scaling factors shows that considerable rescaling of atomic functions occurs in molecules, the largest effects being observed for hydrogen and carbon. However, the range of optimum scale factors for each atom is small enough to allow the selection of a standard molecular set. The use of this standard basis gives theoretical equilibrium geometries in reasonable agreement with experiment.
8,551 citations
TL;DR: In this paper, the Fourier transform of the pair correlation function is used to calculate the structure factor of a reference system in which the intermolecular forces are entirely repulsive and identical to the repulsive forces in a Lennard-Jones fluid.
Abstract: The different roles the attractive and repulsive forces play in forming the equilibrium structure of a Lennard‐Jones liquid are discussed. It is found that the effects of these forces are most easily separated by considering the structure factor (or equivalently, the Fourier transform of the pair‐correlation function) rather than the pair‐correlation function itself. At intermediate and large wave vectors, the repulsive forces dominate the quantitative behavior of the liquid structure factor. The attractions are manifested primarily in the small wave vector part of the structure factor; but this effect decreases as the density increases and is almost negligible at reduced densities higher than 0.65. These conclusions are established by considering the structure factor of a hypothetical reference system in which the intermolecular forces are entirely repulsive and identical to the repulsive forces in a Lennard‐Jones fluid. This reference system structure factor is calculated with the aid of a simple but accurate approximation described herein. The conclusions lead to a very simple prescription for calculating the radial distribution function of dense liquids which is more accurate than that obtained by any previously reported theory. The thermodynamic ramifications of the conclusions are presented in the form of calculations of the free energy, the internal energy (from the energy equation), and the pressure (from the virial equation). The implications of our conclusions to perturbation theories for liquids and to the interpretation of x‐ray scattering experiments are discussed.
4,462 citations
TL;DR: In this paper, the authors studied possible motions for one polymer molecule P performing wormlike displacements inside a strongly cross-linked polymeric gel G. The topological requirement that P cannot intersect any of the chains of G is taken into account by a rigorous procedure: the only motions allowed for the chain are associated with the displacement of certain "defects" along the chain.
Abstract: We discuss possible motions for one polymer molecule P (of mass M) performing wormlike displacements inside a strongly cross‐linked polymeric gel G. The topological requirement that P cannot intersect any of the chains of G is taken into account by a rigorous procedure: The only motions allowed for the chain are associated with the displacement of certain “defects” along the chain. The main conclusions derived from this model are the following:(a) There are two characteristic times for the chain motion: One of them (Td) is the equilibration time for the defect concentration, and is proportional to M2. The other time (Tr) is the time required for complete renewal of the chain conformation, and is proportional to M3.(b) The over‐all mobility and diffusion coefficients of the chain P are proportional to M−2.(c) At times t < Tr the mean square displacement of one monomer of P increases only like 〈(rt − r0)2〉 = const t1/4.These results may also turn out to be useful for the (more difficult) problem of entangle...
3,467 citations
TL;DR: In this article, an equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus-Yevick integral equation.
Abstract: An equation of state is proposed for the mixture of hard spheres based on an averaging process over the two results of the solution of the Percus–Yevick integral equation for the mixture of hard spheres. Compressibility and other equilibrium properties of the binary mixtures of hard spheres are calculated and they are compared with the related machine‐calculated (Monte Carlo and molecular dynamics) data. The comparison shows excellent agreement between the proposed equation of state and the machine‐calculated data.
1,894 citations
TL;DR: In this article, the most stable conformation has an O···H distance of 1.89 A with
Abstract: Ab initio LCAO–MO–SCF calculation for H2CO···H2O is carried out with a minimal Slater basis set. The most stable conformation has an O···H distance of 1.89 A with
1,608 citations
TL;DR: In this article, an extension of the classical trajectory approach is proposed that may be useful in treating many types of nonadiabatic molecular collisions, where nuclei are assumed to move classically on a single potential energy surface until an avoided surface crossing or other region of large NDE coupling is reached.
Abstract: An extension of the classical trajectory approach is proposed that may be useful in treating many types of nonadiabatic molecular collisions. Nuclei are assumed to move classically on a single potential energy surface until an avoided surface crossing or other region of large nonadiabatic coupling is reached. At such points the trajectory is split into two branches, each of which follows a different potential surface. The validity of this model as applied to the HD2+ system is assessed by numerical integration of the appropriate semiclassical equations. A 3d “trajectory surface hopping” treatment of the reaction of H+ with D2 at a collision energy of 4 eV is reported. The excellent agreement with experiment is an encouraging indication of the potential usefulness of this approach.
1,416 citations
TL;DR: In this paper, a sample of water, consisting of 216 rigid molecules at mass density 1 gm/cm3, has been simulated by computer using the molecular dynamics technique, subject to an effective pair potential that incorporates the principal structural effects of manybody interactions in real water.
Abstract: A sample of water, consisting of 216 rigid molecules at mass density 1 gm/cm3, has been simulated by computer using the molecular dynamics technique. The system evolves in time by the laws of classical dynamics, subject to an effective pair potential that incorporates the principal structural effects of many‐body interactions in real water. Both static structural properties and the kinetic behavior have been examined in considerable detail for a dynamics ``run'' at nominal temperature 34.3°C. In those few cases where direct comparisons with experiment can be made, agreement is moderately good; a simple energy rescaling of the potential (using the factor 1.06) however improves the closeness of agreement considerably. A sequence of stereoscopic pictures of the system's intermediate configurations reinforces conclusions inferred from the various ``run'' averages: (a) The liquid structure consists of a highly strained random hydrogen‐bond network which bears little structural resemblance to known aqueous crys...
1,192 citations
TL;DR: In this paper, the mean spherical model is solved in closed form for a fluid of hard spheres with permanent electric dipole moments, and the solutions are expressed in terms of the solution of the Percus-Yevick equation for hard spheres for both positive and negative densities.
Abstract: The mean spherical model is solved in closed form for a fluid of hard spheres with permanent electric dipole moments. Both the pair distribution function g(12) and the direct correlation function c(12) consist of a spherically symmetric term and two other terms with different dependences on the orientations of the two dipole moments. The spherically symmetric part is the solution of the Percus‐Yevick equation for hard spheres. The angle‐dependent terms satisfy two coupled integral equations, which can be decoupled by appropriate changes of the dependent variables. The solutions are expressed in terms of the solution of the Percus‐Yevick equation for hard spheres for both positive and negative densities. The effect on g(12) of the finite size of the sample is calculated for the case of a sphere. The correction term in g(12) is found to be of order 1/V, where V is the volume of the sample. It is a function not only of the relative distance vector of the two molecules, but also of their positions in the sample. The contribution to the polarization is, nevertheless, constant throughout the sample, in agreement with classical electrostatics. The dielectric constant e, calculated by Kirkwood's formula, is obtained in closed form. It is a function of a single variable which does not contain the hard sphere diameter.
630 citations
TL;DR: For nearly spherical molecules, the x-ray scattering from liquids yields structure and correlation functions for molecular scattering centers as discussed by the authors, which provide a sensitive test for future work on a molecular theory of liquid water.
Abstract: For nearly spherical molecules the x‐ray scattering from liquids yields structure and correlation functions for molecular scattering centers. The distribution of electron density in a water molecule is very nearly spherical, and orientational correlation between molecules in the liquid is not ``seen'' by x rays. Structure and correlation functions for molecular scattering centers are derived from x‐ray data on water and tabulated. They provide a sensitive test for future work on a molecular theory of liquid water.
618 citations
TL;DR: In this paper, the effect of molecular symmetry on the two-photon absorption constants of a randomly oriented sample of molecules is considered. But the authors only consider the case where the molecules are randomly oriented.
Abstract: We consider the effect of molecular symmetry on the two‐photon absorption constants of a randomly oriented sample of molecules. It is shown that a complete polarization study of an allowed two‐photon transition of a fluid generally yields enough information to permit an unequivocal identification of the symmetry species of the excited state. Ambiguities occur in only a few cases. Thus, oriented molecule studies for symmetry assignment will be largely unnecessary in two‐photon molecular spectroscopy. Symmetry assignment rules are given for all of the 32 crystallographic point groups and for the two groups of linear molecules. It is shown that certain transitions, which are allowed for two photons of different energies, are forbidden for two photons of the same energy. The application of this formalism to Raman scattering problems is discussed.
501 citations
TL;DR: In this article, a statistical theory of paramagnetic clusters for which large unquenched orbital angular momentum is present, rendering the conventional approach completely inoperative, has been discussed.
Abstract: The statistical theory of paramagnetic clusters described in the literature to date is largely restricted to ``spin‐only'' magnetism for which orbital angular momentum is quenched, or enters the calculations only as a trivially modified g factor. This paper discusses the extension of the theory to magnetic ions for which large unquenched orbital angular momentum is present, rendering the conventional approach completely inoperative. A theory is developed in detail for cobaltous cluster complexes, the cobaltous ion generally being one of the more difficult of the 3d transition metal ions to describe statistically. A preamble into relevant crystal‐field theory is followed by the development of a statistical theory valid, to a good approximation, over the entire temperature range. Numerical results are presented to indicate the separate effects of spin—orbital reduction, and inter‐ as well as intracluster exchange. The full theory is also compared numerically with the results of simpler, but less adequate, a...
TL;DR: In this paper, a steady state is established where there is a dynamic balance between the effect of the pulses and spin relaxation, and the deviation of the intensity of the free induction signal from its thermal equilibrium value is an exponential function of the pulse interval with time constant equal to the spin-lattice relaxation time.
Abstract: When a nuclear spin system is subjected to a repetitive sequence of strong radiofrequency pulses, a steady state is established where there is a dynamic balance between the effect of the pulses and spin relaxation. Under certain readily satisfied pulse conditions, the deviation of the intensity of the free induction signal from its thermal equilibrium value is an exponential function of the pulse interval with time constant equal to the spin–lattice relaxation time. The determination is unaffected by spin–spin relaxation provided that the interval between pulses is long enough to permit all transverse components of magnetization to be eliminated, and provided precautions are taken to inhibit spin‐echo formation. Through Fourier transformation of the transient response, high resolution spectra with many component resonances may be studied, and the spin–lattice relaxation times of the individual lines determined. The technique lends itself particularly well to repeated accumulation of the transient signal for the purpose of improving sensitivity. It has been applied to the problem of determining the spin–lattice relaxation rates of the eight different carbon‐13 resonances in 3,5‐dimethylcyclohex‐2‐ene‐1‐one. The results span a range from 2.6 to 39 sec, and are in good agreement with those obtained by applying 180°–t–90° sequences to the same sample.
TL;DR: In this paper, a double focusing electrostatic electron spectrometer has been used to measure the K-LL Auger spectra resulting from electron impact for each of the elements in the gaseous molecules N2, O2, CO, NO, H2O, and CO2.
Abstract: A double‐focusing electrostatic electron spectrometer has been used to measure the K—LL Auger spectra resulting from electron impact for each of the elements in the gaseous molecules N2, O2, CO, NO, H2O, and CO2. An energy resolution of 0.09% full width half‐maximum was normally employed. A method for analyzing these complex spectra is described. It involves the identification of normal and satellite lines. The former are defined as arising from single electron ionization from the K shell without additional excitation followed by an Auger process in which one electron fills the vacancy while a second goes into the continuum, and where all the other electrons remain in their same orbitals. Satellite lines result when extra excitation occurs either in the initial formation of the K vacancy or in the subsequent Auger process. To aid in the identification of these satellite lines, auxiliary experiments have been performed such as the study of discrete energy losses in photoionization due to electron shake‐up,...
TL;DR: In this paper, the distribution of center-of-mass energy caused by the thermal motion of the target gas molecules has been rigorously derived for the case of a monoenergetic particle beam interacting with target molecules having an isotropic Maxwellian velocity distribution corresponding to temperature T°K.
Abstract: The distribution in center‐of‐mass energy caused by the thermal motion of the target gas molecules has been rigorously derived for the case of a monoenergetic particle beam interacting with target molecules having an isotropic Maxwellian velocity distribution corresponding to temperature T°K. Provided the nominal c.m. energy E0 exceeds a few kT, the distribution has a full width at half‐maximum (FWHM) of W1/2=(11.1γk T E0)1/2. where γ=m/(m+M), m and M being the projectile and target masses. This is identical to the width derived previously in a one‐dimensional approximate treatment by Bethe and Placzek. The exact and approximate distributions differ significantly, however, in shape and mean energy, particularly at low values of E0/γkT. The Doppler width, W1/2, is shown to significantly affect the appearance curve of the products of endothermic reactions involving heavy particles. Convolution integrals are derived for a number of idealized forms of the cross section for such reactions. In the extreme case ...
TL;DR: In this paper, the spin-lattice relaxation times (T1) of individual carbons in solutions of cholesteryl chloride, sucrose, and adenosine 5′-monophosphate (AMP) at 15.08 MHz and 42°C were determined.
Abstract: Proton‐decoupled partially relaxed Fourier transform (PRFT) NMR of carbon‐13 in natural abundance was used to determine spin–lattice relaxation times (T1) of individual carbons in solutions of cholesteryl chloride, sucrose, and adenosine 5′‐monophosphate (AMP) at 15.08 MHz and 42°C. With the exception of a few side‐chain groups, all protonated carbons have T1 values of less than 1 sec. Some side‐chain carbons on cholesteryl chloride show evidence of internal reorientation and have relaxation times of up to 2 sec. Nonprotonated carbons have T1 values in the range 2–8 sec. These relaxation times are sufficiently short to make ordinary Fourier transform NMR a very sensitive technique in the study of complex molecules without the need for spin‐echo refocusing schemes. Integrated intensities and nuclear Overhauser enhancements prove that, except for two of the three nonprotonated carbons in AMP, all 13C nuclei in these compounds relax mainly through 13C–1H dipolar interactions. Measured T1 values of protonated...
TL;DR: Triatomic hydrogen positive ion surface crossing effects in chemical reactions based on potential energy surfaces calculation using diatomics-in-molecules approach were investigated in this paper, where the potential energy surface calculation was carried out using a graph-based approach.
Abstract: Triatomic hydrogen positive ion surface crossing effects in chemical reactions based on potential energy surfaces calculation using diatomics-in- molecules approach
TL;DR: In this article, the authors measured the energy distribution and angular dependence of secondary electrons generated by the impact of 100−2000eV electrons on He, N2, and O2 and measured the shape of the spectra of all the gases, except Ar, Kr, and Xe.
Abstract: The energy distribution and angular dependence of secondary electrons generated by the impact of 100–2000‐eV electrons on He, N2, and O2 and by the impact of 500‐eV electrons on Ne, Ar, Kr, Xe, H2, NO, CO, H2O, NH3, CH4, C2H2, and CO2 have been measured over the 4–200‐eV range. The measurements were made in a crossed‐beam apparatus with the use of a fixed hemispherical electrostatic analyzer and a rotatable electron gun. The observed spectra were integrated over angle to obtain relative cross sections for secondary‐electron production. It was found that the shapes of the spectra of all the gases (except Ar, Kr, and Xe, which contain intense electron emission features in this energy range) were smooth and qualitatively similar, approaching a constant cross section at low secondary energies, and falling off at high secondary energies slightly faster than Es−2, where E8 was the energy of the secondary. The shape of the spectrum was found to be nearly independent of primary energy in He, O2, and N2.
TL;DR: In this paper, Monte Carlo and lattice dynamics were used to determine fluid and face centered cubic solid thermodynamic properties for classical particles interacting with pairwise-additive inverse 4th, 6th, and 9th power potentials.
Abstract: The two computer methods of Monte Carlo and lattice dynamics are used to determine fluid and face‐centered‐cubic solid thermodynamic properties for classical particles interacting with pairwise‐additive inverse 4th, 6th, and 9th power potentials. These results, together with those already on hand for 12th power and hard‐sphere potentials, provide a complete, and remarkably simple, description of the dependence of the pure‐phase thermodynamics and the melting transition on the “softness” of the pair potential.
TL;DR: In this article, the dielectric permittivity and the Dielectric loss factor of 5 methyl-3, 4 methylmethyl-3 and 3 methylpentane were measured from 50 to 105 Hz and from −196 to about 20°C above their respective glass transition temperatures.
Abstract: The dielectric permittivity and the dielectric loss factor of 5‐methyl‐3, 4‐methyl‐3 and 3‐methyl‐3‐heptanol, n‐ and iso‐butanol, 1,2‐propanediol, dimethyl and diethyl phthallate, and 3‐methylpentane have been measured from 50 to 105 Hz and from −196 to about 20°C above their respective glass transition temperatures. The glass transition temperature Tg of these substances, several more isomeric octanols, and 1‐phenyl‐1‐propanol have been measured by differential thermal analysis. All substances except for 3‐methylpentane and iso‐butanol show either a well‐defined secondary relaxation peak in tanδ, or a clear indication of the presence of a secondary relaxation below their Tg's. Arrhenius plots for the α‐relaxation process of the isomeric octanols are linear with an activation energy of 16–18 kcal/mole, while for other substances they are nonlinear with the activation energy changing from 30 to 70 kcal/mole. The Arrhenius plots for the secondary relaxations are linear and have an activation energy of 4–8 k...
TL;DR: In this paper, first-row molecular orbital calculations of first row atom (C, N, O and F) NMR chemical shifts are presented for a variety of polyatomic molecules.
Abstract: Ab initio molecular orbital calculations of first row atom (C, N, O and F) NMR chemical shifts are presented for a variety of polyatomic molecules. Both minimal and extended basis sets are used and it is shown that at the minimal level, basis sets at the Hartree–Fock atomic level give a better description of magnetic shielding than do Slater‐type (exponential) orbitals. The extended basis set also gives a good description of magnetic shielding, features associated with anisotropic molecular environment being some‐what more adequately treated at this level. Calculated chemical shifts of nuclei which have similar positions relative to the origin of the vector potential describing the magnetic field are in good agreement with experiment. Agreement for the chemical shifts of nuclei which have markedly different positions relative to this origin is not as good.
TL;DR: In this article, an analysis of the distribution function and its moments for a linear combination of three randomly chosen orthogonal components of the so-called radius of gyration of an unrestricted random-flight chain is made, and certain averages of moments are obtained of the three-dimensional distribution W (L12L22L32L32).
Abstract: An analysis is made of the distribution function and its moments for a linear combination of three randomly chosen orthogonal components of the so‐called radius of gyration of an unrestricted random‐flight chain, and certain averages of moments are obtained of the three‐dimensional distribution W (L12L22L32), where L1 ≤ L2 ≤ L3 are the orthogonal components of the radius of gyration along the principal axes of inertia of the chain The strong departures of the chain shape from spherical symmetry indicated by these results are confirmed and complemented by Monte Carlo studies of unrestricted random walks on a simple cubic lattice A surprisingly high ratio of principal components is found for chains with 50 and 100 bonds, 〈L32〉: 〈L22〉: 〈L12〉 ≃ 117:27:1
TL;DR: In this article, the Hartree-Fock representation of the first row atoms and hydrogen was investigated by means of Hartree Fock calculations on the water and nitrogen molecules, and it was found that a two-term Gaussian expansion is required to adequately represent the 3D polarization functions of hydrogen and water, whereas a single Gaussian function is sufficient.
Abstract: The representation of polarization functions for the first row atoms and hydrogen is investigated by means of Hartree—Fock calculations on the water and nitrogen molecules. It is found that a two‐term Gaussian expansion is required to adequately represent the 3d polarization functions of the first row atoms, whereas for the 2p polarization functions of hydrogen, a single Gaussian function is sufficient. The interaction of oxygen and hydrogen polarization functions in the water molecule is briefly discussed.
TL;DR: In this article, the wavelength dependence across the visible region of the intensity of the 1334 cm−1 Raman line of p−nitroaniline (PNA) was analyzed from a general theoretical viewpoint.
Abstract: Experiments on the wavelength dependence across the visible region of the intensity of the 1334‐cm−1 Raman line of p‐nitroaniline (PNA) are analyzed from a general theoretical viewpoint. When theory is simplified to correspond to the PNA example, two obvious sources of Raman intensity are apparent. One is based on a possible shift of equilibrium nuclear position along the 1334‐cm−1 mode upon exciting PNA into its first excited singlet state (in the near ultraviolet). The other source deals with vibronic coupling of the first excited electronic state with a whole family of states in the deep ultraviolet having similar polarizations. It is seen how this second mechanism appears to be the dominant one in this case. The absolute scattering cross section for the 1334 cm−1 is given and is found to agree with the order of magnitude estimates calculated theoretically.
TL;DR: In this article, the authors studied the migration of Frenkel excitons in molecular crystals, starting from the microscopic equations of motion for the exciton density, and found that the migration process is diffusionlike on a long time scale for all temperatures as long as exciton-phonon coupling is present.
Abstract: The migration of Frenkel excitons in molecular crystals is studied theoretically, starting from the microscopic equations of motion for the exciton density. The migration process is found to be diffusionlike on a long time scale for all temperatures as long as the exciton–phonon coupling is present. If there is no exciton–phonon coupling, the migration is wavelike. A discussion of the relevant time scales for the wavelike (coherent) process and the diffusion (incoherent) process is given. Several different approximation techniques, based on the cumulant expansion, projection operator, and functional derivative methods, are shown to be mathematically equivalent as applied to this problem.
TL;DR: The ionic conductivity of the solid electrolyte NaAl11O17 has been measured from − 150 to + 820°C using a novel nonpolarizing solid electrode, reversible to sodium ions as mentioned in this paper.
Abstract: The ionic conductivity of the solid electrolyte NaAl11O17 has been measured from − 150 to + 820°C using a novel nonpolarizing solid electrode, reversible to sodium ions. The resistivity at 25°C was found to be 72 Ω‐cm, the lowest value reported for any ionically conducting oxide ceramic. The enthalpy of motion is 3.79 kcal/mole, and the transport of sodium ions takes place by an interstitialcy mechanism.
TL;DR: In this article, the x-ray scattering by two different rutile crystals, within a hemisphere of reciprocal space having radius (sin θ) /λ=1.02 A−1, was measured at 298°K with PEXRAD.
Abstract: The x‐ray scattering by two different rutile crystals, within a hemisphere of reciprocal space having radius (sin θ) /λ=1.02 A−1, was measured at 298°K with PEXRAD. The integrated intensities of 780 reflections from each crystal were determined, resulting in 136 symmetry independent Fmeas from Crystal 1 and 122 Fmeas from Crystal 2. The crystal structure was refined by the method of least squares: The agreement factor R for all Fmeas is 0.0286, and the single position parameter x(0)=0.30479±0.00010. Normal probability plot analysis shows the least squares derived standard deviations are underestimated by 33%, and the two sets of Fmeas contain an appreciable parallel bias. The lattice constants, measured at or corrected to 298°K on two different crystals, are a=4.593659±0.000019 and c=2.958682±0.000008 A. The Ti–O distances are 1.9800±0.0009 and 1.9485±0.0005 A. Pairs of shorter bonds define O–Ti–O angles of 81.21° and 98.79°, forming a plane normal to the two longer bonds. The resulting octahedral Ti–O bo...
TL;DR: In this paper, an effective Hamiltonian for a given subsystem which should properly describe the states of that subsystem is determined. But the work of McWeeny, in which one assumes strong orthogonality among subsystem wavefunctions, has not been considered.
Abstract: Atomic and molecular systems are often intuitively separated into almost independent subsystems as, for example, the core and valence parts of an atom. Consequently, if this separation provides a good approximation, one can obtain the states of the system from the states of the subsystems which best represent the entire system. In the light of the work of McWeeny, in which one assumes strong orthogonality among subsystem wavefunctions, we determine an effective Hamiltonian for a given subsystem which should properly describe the states of that subsystem. Previous work is shown to have dealt with an improper effective Hamiltonian.
TL;DR: In this article, the spectrum for large frequency shifts based on a binary interaction picture employing a Lennard-Jones potential and a short range electronic overlap distortion model is calculated for liquid argon.
Abstract: Measurements of light scattered in the Rayleigh wing were made over the range from 5 to 500 cm−1 in CCl4, C6H12, C5H12, CH3OH, C2H5OH, H2O, NH3, and CHCl3. These data when compared with earlier data on Ar, Xe, and SnBr4 indicate that in all of these liquids there is present the essentially exponential frequency dependence typical of collision induced effects. A calculation of the spectrum for large frequency shifts based on a binary interaction picture employing a Lennard‐Jones potential and a short range electronic overlap distortion model agrees well with the experimental results in liquid argon. Further, assuming that molecular frame distortion is proportional to the interaction force, a similar calculation yields excellent agreement for the molecular systems. It is concluded that isolated binary interactions are mainly responsible for the spectral density in the wings of the Rayleigh spectrum.
TL;DR: For the first time, phosphorescence has been observed from and clearly assigned to the molecular triplet of several metallophthalocyanine (Pc) molecules as discussed by the authors.
Abstract: For the first time, phosphorescence has been observed from and clearly assigned to the molecular triplet of several metallophthalocyanine (Pc) molecules. The Pc's of Pt, Pd, Cu, Zn, and Cd have O–O bands in solution (77°K) at the extraordinarily low energies of 10 590, 10 100, 9390, 9150, and 9120 cm−1, respectively, while those of Mg and VO have possible transitions at ∼9000 and 8500–8800 cm−1. Half‐widths, lifetimes, approximate quantum efficiencies, triplet absorption, and excitation spectra, and vibrational substructure are reported, together with oxygenation and heavy atom effects. The lifetimes were very short (varying from 1 msec to less than 3 μsec), so room temperature phosphorescence was seen, as was radiation from the separate triplet sublevels at 4°K and below. Yields were very low (∼10−2 to ∼10−5) because of very strong radiationless transitions, and various other Pc complexes did not seem to phosphoresce at all. Both tripdoublet and quartet luminescence were seen from CuPc, and the intersyst...