Electronic to vibrational energy transfer assisted by interacting transition dipole moments: a quantum model for the nonadiabatic I2(E) + CF4 collisions

Fluorescence and room temperature activity of Y2O3:(Eu3+,Au3+)/palygorskite nanocomposite

Palygorskite supported Y₂O₃:(Eu³⁺,Au³⁺) nanocomposites show simultaneous fluorescence and catalytic activities.

Experimental interrogation of the multidimensional He + ICl(E, v(dagger)) and He + ICl(beta, v(dagger)) intermolecular potential energy surfaces

Resonant two-photon excitation of the T-shaped and linear He...I(35)Cl(X,v(") = 0) complexes is used to access the intermolecular vibrational levels bound within the He + ICl(beta,v(dagger) = 0-2) and He + ICl(E,v(dagger) = 11,12) intermolecular potentials. The excitation utilizes different metastable intermolecular vibrational levels within the He + ICl(A,v(') = 15) and He + ICl(B,v(') = 2,3) potentials to access levels with varying intermolecular vibrational excitation in the ion-pair states. In addition to providing data revealing properties of the He + ICl(E,v(dagger)) and He + ICl(beta,v(dagger)) potentials, the transition energies of the observed features permit the relative binding energies of the T-shaped and linear ground-state He...ICl(X,v(") = 0) conformers to be accurately measured. The binding energies of the T-shaped and linear He...I(35)Cl(X,v(") = 0) conformers are 16.6(3) and 22.0(2) cm(-1), respectively. These values and the observed transition energies are then used to set the binding energies of the T-shaped He...I(35)Cl complexes in the He + ICl(A,v(') = 15), He + ICl(B,v(') = 3), He + ICl(beta,v(dagger) = 1), and He + ICl(E,v(dagger) = 12) potentials as 13.4(3), 13.3(3), 41(1), and 39.2(4) cm(-1), respectively. Nonadiabatic coupling between specific intermolecular vibrational levels within the He + ICl(beta,v(dagger)) state and the ICl(D('),v(dagger)) molecular state is observed.

Dynamics and mechanism of the E-->D, D', beta, gamma, and delta nonadiabatic transitions induced in molecular iodine by collisions with CF4 and SF6 molecules

Nonadiabatic transitions among the first-tier ion-pair states of the iodine molecule in collisions with CF(4) and SF(6) partners are investigated by detecting the luminescence following the optical-optical double resonance excitation of the E0(g) (+)-state to the vibrational levels v(E)=8, 13, and 19. Total and partial rate constants, as well as vibrational product state distributions, are determined. It is found that electronic energy transfer in all channels is predominantly assisted by excitation of the dipole-allowed nu(3) and nu(4) modes of the partner. The measurements are accompanied by quantum scattering calculations that implement a close coupling treatment for the electronic and vibrational degrees of freedom and combine diatomics-in-molecule and long-range models for diabatic potential energy surfaces and coupling matrix elements. The analysis of experimental and theoretical data shows that the transitions without excitation of the partner are due to short-range couplings, whereas the vibrational excitation of the partner in the D0(u) (+) channel originates from the long-range coupling of two transition dipole moments: electronic of the iodine molecule and vibrational of the partner. Unexpectedly efficient excitations of the partner in the other ion-pair states, which are not coupled to the initial E0(g) (+)-state by the transition dipole, are interpreted within the postcollision mechanism. Qualitatively, this implies that during a single collision the long-range nonadiabatic transitions to D, nu(3) and D, nu(4) channels are followed by secondary short-range transitions without changing the state of the partner.

Theoretical and experimental studies of collision-induced electronic energy transfer from v=0-3 of the E(0g +) ion-pair state of Br2: collisions with He and Ar

Collisions of Br(2), prepared in the E(0(g)+) ion-pair (IP) electronic state, with He or Ar result in electronic energy transfer to the D, D', and beta IP states. These events have been examined in experimental and theoretical investigations. Experimentally, analysis of the wavelength resolved emission spectra reveals the distribution of population in the vibrational levels of the final electronic states and the relative efficiencies of He and Ar collisions in promoting a specific electronic energy transfer channel. Theoretically, semiempirical rare gas-Br(2) potential energy surfaces and diabatic couplings are used in quantum scattering calculations of the state-to-state rate constants for electronic energy transfer and distributions of population in the final electronic state vibrational levels. Agreement between theory and experiment is excellent. Comparison of the results with those obtained for similar processes in the IP excited I(2) molecule points to the general importance of Franck-Condon effects in determining vibrational populations, although this effect is more important for He collisions than for Ar collisions.