Studies on dissociation energies of diatomic molecules using vibrational spectroscopic constants

New analytical expression and numerical approach are suggested to calculate dissociation energies De of diatomic molecular states using an extreme value method (EVM). Studies on some electronic states of OH, BH, N2, Br2, ClF and CO molecules show that the accuracy of the EVM dissociation energies depends on the number of correct vibrational constants used in the calculations. The convergence qualities of De are suggested to be an alternative physical criterion to measure the qualities of the various sets of vibrational constants from different literature for the same diatomic state.     

The method of concentration pulses for studying hydrogen transport in solids

The method of concentration pulses is designed for investigating the kinetics of hydrogen transport in complex diffusion systems and allows one to choose the most probable transport model and determine the rate constants of processes influencing the kinetics, e.g., diffusion, adsorption, and desorption, capture to traps, etc. We describe the idea of the method, its experimental realization, and a procedure for processing the results which allows one to choose the most probable model and determine the desired rate constants. Zh. Tekh. Fiz. 69, 99–103 (January 1999)     

Coupling and dissociation in artificial molecules

We show that the spin-and-space unrestricted Hartree-Fock method, in conjunction with the companion step of the restoration of spin and space symmetries via Projection Techniques (when such symmetries are broken), is able to describe the full range of couplings in two-dimensional double quantum dots, from the strong-coupling regime exhibiting delocalized molecular orbitals to the weak-coupling and dissociation regimes associated with a Generalized Valence Bond combination of atomic-type orbitals localized on the individual dots. The weak-coupling regime is always accompanied by an antiferromagnetic ordering of the spins of the individual dots. The cases of dihydrogen (H₂, 2e) and dilithium (Li₂, 6e) quantum dot molecules are discussed in detail. Received 19 December 2000     

Pressure dissociation of dense hydrogen

The self-consistent fluid variational model （SFVM） has been used to describe the pressure dissociation of dense hydrogen at high temperatures. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. The equation of state and dissociation degree have been calculated from the free energy functions in the range of temperature 2000-10,000K and density 0.02-1.0g/cm^3, which can be compared with other approaches and experiments. The pressure dissociation is found to occur in higher density range, while temperature dissociation is a more gradual effect.     

Spontaneous radiative dissociation in molecular hydrogen

The spontaneous radiative dissociations of the discrete vibrational levels of the B¹Σ⁺_u electronic states of H₂, HD and D₂ of the C¹Π_u electronic state of H₂ into the vibrational continuum of the ground X¹Σ⁺_g state are calculated as a function of the emission wavelength. The fluorescent spectra of HD in the Lyman system and of H₂ in the Werner system resulting from an excitation source uniform in wavelength are predicted. The vibrational radiative lifetimes are tabulated as are the fractions of radiative decays that lead to dissociation. The effects of centrifugal distortion are discussed briefly. An appendix describes a sum rule used to check the numerical accuracy of the calculations.     

Spontaneous dissociation of long-range Feshbach molecules

We study the spontaneous dissociation of diatomic molecules produced in cold atomic gases via magnetically tunable Feshbach resonances. We provide a universal formula for the lifetime of these molecules that relates their decay to the scattering length and the loss rate constant for inelastic spin relaxation. Our universal treatment as well as our exact coupled channels calculations for 85Rb dimers predict a suppression of the decay over several orders of magnitude when the scattering length is increased. Our predictions are in good agreement with recent measurements of the lifetime of 85Rb(2).     

Equivalent two-level atom method for calculating the kinetics of cosmological hydrogen recombination

The effective coefficient of recombination to the second level, which enters the equations describing the recombination kinetics in the cosmological HII region, is calculated. The calculation method is based on the quasi-steady-state approximation and makes it possible to adequately consider cascade transitions and induced processes without the necessity to numerically solve a complete set of corresponding kinetic equations.     

Self-entanglement and the dissociation of homonuclear diatomic molecules

The concept of self-entanglement is introduced to describe a mixed state or ensemble density as a pure state in an augmented Hilbert space formed by the products of the individual states forming a mixed state (or ensemble). We use this representation of mixed states to show that upon dissociation a neutral homonuclear diatomic molecule will separate into two neutral atoms.     

The steering of molecules in simple dissociation reactions

The effectiveness of steering in simple dissociation reactions has been studied by performing classical and quantum simulations on a wide range of model potentials. By parametrically varying the PES landscape, it is shown how trends in the translational energy dependence of the dissociation probability may be related to particular topographical features. The relationship between the strength of attractive and repulsive regions determines the force which a molecule feels, but in addition we show that the range of the force helps determine the degree of repositioning and reorientation. The presence of wells along the reaction coordinate is considered, and it is shown how the snarled trajectories which frequently result relate to precursor-like behaviour even in the absence of dissipative processes.     

Triple-ionization-induced dissociation of molecules in strong laser fields

We study triple-ionization-induced dissociation in diatomic molecules with different laser polarizations.     

计算氢同位素水分子汽化焓的比较法

本文首次提出计算氢同位素水分子汽化焓的比较法,得到0～374℃时H2O,D2O,DTO和T2O的汽化焓,并提出用D2从含氚重水中分离出DT气的适宜温度.     

Spontaneous dissociation of 85Rb Feshbach molecules

The spontaneous dissociation of 85Rb dimers in the highest lying vibrational level has been observed in the vicinity of the Feshbach resonance that was used to produce them. The molecular lifetime shows a strong dependence on magnetic field, varying by 3 orders of magnitude between 155.5 G and 162.2 G. Our measurements are in good agreement with theoretical predictions in which molecular dissociation is driven by inelastic spin relaxation. Molecule lifetimes of tens of milliseconds can be achieved within approximately a 1 G wide region directly above the Feshbach resonance.