J.J. Camacho

Synthesis and photophysical properties of some N-substituted-1,8-naphthalimides

Abstract The synthesis and photophysical properties of some 3-amino-N-substituted-1,8-naphthalimide derivatives are presented. The flourescence behaviour of these compounds in protic and aprotic solutions is consistent with the formation of an exciplex structure. The exciplex formation is due to a proton transfer in the excited state. This exciplex formation eliminates non-radiative channels and therefore an increase in quantum yield is observed.

PMO-RKR-van der Waals potential energy curves for the X1Σ+ and A1Σ+ states of the isotopic lithium hydrides

Abstract The potential energy curves for the X 1 Σ + and A 1 Σ + states of lithium hydrides and deuterides have been calculated by a new procedure which uses: (a) a perturbed Morse oscillator for the minimum zone; (b) a Rydberg-Klein-Rees potential for the zone of energy levels which can be represented from the experimental data; (c) a van-der Waals-type potential for the asymptotic part of the potential. All the calculated potentials have been checked by solving numerically the radial Schrodinger equation. From the wavefunctions generated we have obtained the vibrational energy eigenvalues and B v values, observing a very good agreement with the experimental data.

The C(2)1Πu state of Na2 molecule studied by polarization labelling spectroscopy method

The C1pi(u) <-- X1sigma(g)+ system of Na2 is studied by the polarization labelling spectroscopy technique. Accurate molecular constants are derived for the observed levels nu = 0-12, J = 12-100 in the C1pi(u) state.

The A1Σ+-X1Σ+ band system of the KH and KD molecules

Abstract The molecular constants of the A1Σ+ and X1Σ+ states of the KH and KD molecules have been determined using mass relations correspondent to a normal isotope shift. For the calculation we have used data of the laser-induced fluorescence spectrum by the Ar+ 4881 A exciting line photographed in our laboratory, as well as previous data presented by other authors. From the spectroscopic terms, quantum-mechanical PMO-RKR-van der Waals hybrid potentials have been generated. Numerical calculations for the A1Σ+ and X1Σ+ states of the KH and KD species are comapred with quantum-mechanical values obtained by numerical solution of the radial Schrodinger equation. Vibrational wavefunctions appropriate to the potential curves yield values of Eυ and Bυ which are in close agreement with the experimental results. The probability distribution functions and Franck-Condon factors for the A1Σ+ ↔ X1Σ+ band system have also been determined. It is observed that the anomalous behaviour of the A state is clearly revealed with a changed anharmonicity for the lowest vibrational levels.

The padé-approximant method and its applications in the construction of potential-energy curves for the lithium hydride molecule

Abstract Analytical expressions, self-consistent with experimental data, have been obtained starting from hybrid PMO-RKR-van der Waals potentials for the different isotopic species of lithium hydride. Different power series expansions have been tested; Pade approximants give the best statistical parameters in a least-squares fit. These analytical potentials can be used to obtain the entire potential energy curve, approximating the experimental dissociation energy accurately. As a test of the precision of the proposed analytical potentials the vibrational and rotational energy eigenvalues have been calculated and agree to within 0.01 cm −1 with eigenvalues obtained by solving the initial radial wave equation numerically.

Experimental and theoretical radiative lifetimes for some β-carboline derivatives

Abstract The photophysical properties (absorption and fluorescence spectra, quantum yields and fluorescence lifetimes) for neutral and cationic species of seven β-carboline derivatives were studied in ethanol solution. The ratio between experimental and theoretical radiative lifetimes was obtained. These values suggest that there is a configurational change between the ground state and the excited state. The ΔpK values obtained from the Foster-Weller cycle corroborate this interpretation. The photophysical behaviour of these derivatives can also be explained in terms of the curves obtained by plotting energy vs. the β-carboline ring-proton distance.

Accurate potential energy curves for the X 1Σ+ and A1Σ+ states of NaH

Abstract A reanalysis of the spectroscopic data for the ground and excited states of NaH yields improved spectroscopic constants (Dunham coefficients) which are used to compute new PMO-RKR-van der Waals potentials. The vibrational wavefunctions appropriate to the potential were used to obtain the eigenvalues E ν , the rotational constant B ν and the centrifugal distortion terms D ν , H ν and L ν . They are in agreement with the experimental results within the accuracy of the measurements, as would be expected. Probability density distributions and Franck-Condon factors are calculated for the A 1 Σ + ⇌ X 1 Σ + band system of NaH. It is found that the probability distribution functions for the A 1 Σ + state show little asymmetry (as in harmonic oscillator) rather than the typical asymmetry favoring larger distances.

The intensity behaviour of the laser-induced fluorescence spectrum in the KH molecule

Abstract Collisional processes involving changes in rotational and vibrational quantum numbers are detected in laser induced fluorescence spectrum of KH molecule. The knowledge of the Franck-Condon factors in the involved transitions allows us to evaluate a relative variation of R2e versus the ν″ vibrational quantum number. In the same context a population analysis was made for the ν′ = 7 vibrational level.

Photocounting system for lifetime measurements. application to a naphthalic derivative

Abstract The lifetime of a naphthalic acid imide derivative in different solvents is analyzed. In lifetime measurements a photocounting system is utilized. Deconvolution is used in data analysis.

The potential energy curves and probability density distributions of the X1Σ+ and A1Σ+ states of RBH

Abstract The potential energy curves PMO—RKR—van der Waals of the electronic A 1 Σ + and X 1 Σ + states of RbH have been determined. The potentials obtained are self-consistent with the experimental data because they have been tested by direct numerical solution of the radial Schrodinger equation. From exact vibrational eigenfunctions probability density distributions and Franck—Condon factors have been calculated over the range of vibrational levels observed. It is observed that the anomalous behaviour of the A 1 Σ + state arises in the υ′ = 1, 2 and 3 levels with probability density functions similar to those of a harmonic oscillator.