Showing papers in "Chemical Physics in 1980"

TL;DR: In this article, a density matrix formulation of the super-CI MCSCF method is presented, where the MC expansion is assumed to be complete in an active subset of the orbital space, and the corresponding CI problem is solved by a direct scheme using the unitary group approach.

TL;DR: In this article, the authors applied the techniques of laser fluorescence excitation spectroscopy for the experimental study of the rotational-vibrational cooling of iodine (I2) and of several large molecules, i.e., anthracene (C14H10), tetracene, pentacene, and ovalene, in seeded supersonic beams of rare gases, and found that the mass of the rare gas expanded at stagnation pressures of p = 20-8300 Torr and through a nozzle of diameter D = 50-200 μ exhibits a marked

TL;DR: In this paper, nonadiabatic coupling matrix elements of the type z |∂/∂ Q Ψ β > are obtained for large-scale CI wavefunctions, whereby both contributions to the matrix elements, that originating exclusively from the dependence of the CI coefficients on the nuclear variables and that related to the changes in the MO's themselves, are evaluated by the method of finite differences.

TL;DR: In this article, the possible shapes of the ground (U I ) and first excited (U II ) adiabatic potentials are discussed in connection with the electron transfer problem, and the transfer rate W has the form W = B exp(− E A / T ), the preexponential factor B can be influenced by the size of the gap, especially when Γ is small.

TL;DR: In this paper, the distribution of vibrational energy following unimolecular elimination is represented as a distribution of maximal entropy subject to a constraint on the mean vibrational excitation, which depends primarily on the height of the barrier in the elimination channel and, more weakly, on the excess energy above the barrier.

TL;DR: In this article, in-cage reactions are considered in the model of two intersecting parabolic terms different in curvature and lifetime, and transitions between the terms are assumed (contact approximation) possible only at the crossing point that is reached due to diffusion along the terms.

TL;DR: In this paper, the dipole oscillator strenghts for photoabsorption, photoionisation and photofragmentation of N 2 O and CO 2 have been derived from electron energy loss and electron-ion coincidence measurements in the energy range 8 to 75 eV.

TL;DR: In this article, spherical silver microcrystallites with mean diameters between 10 and 200 A have been prepared by gas aggregation techniques using argon gas in a dynamic flow system, and a small quantity of these crystallites were allowed to condense onto an umorphous carbon foil, which allowed a direct characterisation of the size distribution by evaluating the corresponding electron micrographs.

TL;DR: In this article, the IR MPD of C 2 H 3 CN in the presence of O 2, CO molecules in the a 3 Σ +, d 3 Δ i, and e 3 − states were identified, as well as CH(A 2 Δ) and CN(B 2 Σ+ ) radicals.

TL;DR: In this article, the angle dependent potential of the total collision cross section was analyzed for two different orientations of the NO in the 2Π 3 2 state and the absolute value of the collision cross-section.

TL;DR: In this article, a comparison between ionization and fluorescence yields and their spatial structure, following two-photon excitation, under identical experimental conditions is made, showing that radiationless processes are important in determining the ionization yield, which leads to the apparent selectivity of molecular multiphoton ionization experiments toward Rydberg states.

TL;DR: In this paper, the Langevin cross section of strongly coupled collision complexes was shown to correspond to the usual Langevin sub-section only if the kinetic energy is less than 0.2 eV and provided that little initial excitation is present, while for higher kinetic energies it drops exponentially.

TL;DR: The 30.4 nm He(II) photoelectron spectra of fluorine(F2), of acetylene and diacetylene and their fluorosubstituted derivatives have been recorded as mentioned in this paper.

TL;DR: In this paper, the vertical transition energies for the 1s ionization potential and the core-excited 1s → π* and 1s→ 3s, 3p, 3d Rydberg states of acetylene and ethylene are calculated employing a basis of 72 and 76 contracted gaussian AO's respectively in a large-scale ab initio MRD-CI treatment, and the dependence of the calculated results on the size of the AO basis and on scaling the valence and inner shells is discussed, and a direct comparison between the localized and delocal

TL;DR: In this paper, the second quantized boson theory was used to calculate the energies and oscillator strengths of the Coulomb transfer interactions in crystalline naphthalene, anthracene, tetracene and pentacene.

TL;DR: The spectroscopic behaviour of poly(N-vinylcarbazole) prepared by cationic and radicalic polymerisation has been investigated in this article, where it has been found that the delayed fluorescence is due to the mutal annihilation of mobile triplets and trapped ones.

TL;DR: In this article, the Δυ = −1, 0 and 1 sequences of the CS + (B 2 Σ + − A 2 Π i ) system have been identified in the flowing helium afterglow reactions of CS 2 and OCS around 4000 A.

TL;DR: In this paper, photoionization efficiency curves for 39,39K2 and 39,41K2 dimers excited to the B 1 Πu electronic state have been measured using sequential two-photon ionization techniques.

TL;DR: In this paper, the relative photoionization efficiency curves of the fragment ions of O 2, NO, and CO were determined in the energy region 17 eV to 30 eV by means of synchrotron radiation.

TL;DR: In this article, a new optical-radiofrequency double resonance technique was applied to a study of the singlet-triplet interactions for single rotational levels of the vibrationless 1Au state of glyoxal.

TL;DR: In this article, the decay processes of the first and second excited singlet of azulene and some simple derivatives have been examined and the internal conversion rates are interpreted using the Englman-Jortner description of radiationless transitions in the weak coupling limit.

TL;DR: In this article, the T-T energy transfer from aromatic hydrocarbons to trans and cis stilbene has been treated by applying the Ulstrup and Jortner quantum mechanical description of electron transfer reactions.

TL;DR: In this article, a computational method for the treatment of coupled systems of oscillators by a SCF-like formalism is presented for the Henon-Heiles system and extensions to state interaction (analogous to configuration interaction) are presented.

TL;DR: In this paper, it was shown that trans-stilbene is nonplanar in fluid phases and that the Au torsional coordinates are quite anharmonic and strongly coupled.

TL;DR: In this article, an ion-beam apparatus was employed to investigate the reactions of uranium ions and uranium monoxide ions with O 2, CO, CO 2, COS, CS 2 and D 2 O. Reaction cross sections as a function of ion kinetic energy were determined and compared to simple models for exothermic and endothermic reactions.

TL;DR: In this article, the N 1s and O 1s energy regions of the XPS spectra of para-substituted nitrobenzenes and nitro benzenes were investigated.

TL;DR: In this article, a general method of determining the fluorescence and absorption properties of two species from those of the mixture is presented, and the major species (≈0.67) has τ = 27.6 ns, q = 0.66 and a structured F.

TL;DR: In this article, high yield routes to the unstable halogen azides and isocyanates have permitted vacuum ultraviolet photoelectron spectra to be obtained for the chlorine and bromine azides, and the chlorine, brominine and iodine isocalates.

TL;DR: In this article, photofragment spectroscopy of IBr and ICl was used to obtain the repulsive part of the 3 II 0 + potential curve in the Franck-Condon range.

TL;DR: In this article, the two-photon resonant multiphoton ionization (MPI) spectra of methyl iodide and other fundamental molecules are reported in the 49 000-55 000 cm −1 region.