D. K. Rai

Potential-energy curves for O2+, N2+, and CO+

Abstract Experimental potential energy curves have been constructed for the molecules O 2 + , N 2 + , and CO + by the Rydberg-Klein-Rees-Vanderslice method. Perturbations in the A 2 Π state of CO + have been predicted due to the X 2 Σ + state and the observed perturbations in the case of N 2 + have also been discussed.

Potential‐Energy Curves and Dissociation Energies of Oxides and Sulfides of Group IV A Elements

The experimental potential‐energy curves have been calculated for some of the electronic states of the oxides and sulfides of Group IV A elements. These results have been compared with empirical potential functions, and dissociation energies of the molecules have been estimated.

CNDO-CI study of electronic structure and molecular geometry in ground and excited states

The modified CNDO method of Del Bene and Jaffe (CNDO/s) and the CNDO/2 and INDO methods due to Pople have been used to study the electronic structure and geometry of mono- and p-difluorobenzenes in the ground and the first excited singlet states. Bond orders, hybrid populations and transition energies together with the corresponding oscillator strengths have been given. Ground and excited state rotational constants and changes in bond lengths in the excited state as compared to the ground state have also been presented and discussed in the light of experimental observations.

Force constants of metal hexafluorides

Abstract The simple and modified UBFF have been applied to thirteen octahedral metal hexafluorides. The force constants have been adjusted by a least squares method. The force constants show certain regularities. The covalent character of the metal fluoride, metal chloride and metal bromide bonds has been discussed.

Electret microphone for use in photoacoustic spectrometer and photoacoustic spectrum of some rare earth oxide powders

We describe a new method for the polarization of an electret foil which has proved very convenient and yields a foil having very good performance in a microphone. The variations in the charge accumulation on the electret foil and its decay with time as well as the variation of the microphone sensitivity with different microphone parameterse.g. different thicknesses of the electret foil, different back plates and different polarization techniques has been investigated. The sensitivity of the home-made microphone is estimated as 1 mV/μbar. The working of this type of microphone and its comparison with a commercial microphone as used in a (laboratory made) single beam photoacoustic spectrometer is discussed.A brief description of the photoacoustic spectrometer including microphone biasing and the photoacoustic cell is given. The photoacoustic spectra of some rare earth oxides in the form of powders have been recorded. It is seen that the atomic levels of triplyionized rare earths which are not fluorescent appear very prominently in the photoacoustic spectrum. The spectra for terbium and praseodymium oxides do not show clear peaks probably due to the presence of different stoichiometric forms.

Application of classical collision theory to electron impact double ionization of atoms

The classical binary encounter theory in its symmetrical form has been applied to the double ionization of He and Li+. Process of double ionization has been assumed to proceed via double encounter. In both encounters correct quantum mechanical velocity distributions for the bound electron have been used. The results are compared with experimental observations and earlier calculations by Gryzinskis method. It is concluded that the single encounter model suggested by Mittleman (1966) is not entirely correct and substantial contributions are made by double encounter process.

CNDO CI study of electronic structure and geometry in ground and excited states. ortho- and meta- difluorobenzenes

Abstract The modified CNDO/2 method (CNDO/s) has been applied to study the electronic structure and geometry of ortho- and meta-difluorobenzenes in their ground and first excited singlet states. Calculated density matrices have been transformed into σ- and π-bond orders by the technique suggested earlier. Bond lengths have been calculated using the Coulson bond-orderue5f8bond-length relationship and the bond angles were assumed to the 120° in both states of these molecules. The calculated rotational constants are in very good agreement with the experimental measurements recently reported by Hartford and Lombardi.

Maximum Ionization Cross Section of Atoms

Various theoretical approaches for estimation of maximum ionization cross sections have been discussed and three new relations have been developed and used to evaluate maximum cross sections. Manns calculations have been critically examined, and the present results have been compared with available experimental results.

A simple laser power meter dependent on photoacoustic effect

The design and fabrication of a simple laser power meter dependent on the photoacoustic effect is described. This power meter has a sensitivity of 1 mV/3.5 mW laser power and the microphone has a sensitivity of 10 mV/Pa. It can be used in any wavelength region and its calibration is easy.

Ultraviolet spectra and structure of the isomeric dihydroxy- and diamino-substituted benzenes

The semi-empirical all-valence-electron SCF-LCAO-MO-CI method in its Del Bene and Jaffe formalism has been applied to the study of the electronic absorption spectra and structure of isomeric dihydroxy- and diamino-substituted benzenes. The calculated π-π* singlet excitation energies and corresponding oscillator strengths have been compared with earlier π-electron results and discussed in the light of experimental findings. Ionization potentials, electron affinities, ground-state atomic orbital populations and net electronic charges of atoms, have also been presented.