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      https://www.ias.ac.in/article/fulltext/jcsc/103/03/0265-0276

    • Keywords

       

      Two-photon spectroscopy; lanthanide spectroscopy; super-sonic-jet-cooled; spectroscopy; intramolecular exciton interaction

    • Abstract

       

      The complementarity of one- and two-photon spectroscopy has been utilised for throwing light on the following problems of chemical interest: (1) Weak interaction between identical chromophores separated by insulating bridges gives rise to split states of different symmetries. Two-photon spectroscopy (TPA), in conjunction with one-photon absorption (OPA), has been used to identify the states and hence to estimate the magnitude of interaction in bimolecules and trimolecules. From the shifts between the one- and the two-photon spectra, the splittings have been estimated. Calculations confirm that the dominant interaction is the through-bond one. (2) The second type of problem is the identification ofg andu vibrations in molecules. We have initiated studies on three molecules in jet-cooled conditions: 9,10-dihydro-anthracene (DHA). 9,10-dihydro-phenanthrene (DHP) and octa-fluoronaph-thalene (OFN). Only the one-photon fluorescence excitation spectra have so far been obtained by us and the TPA spectra are under investigation. (3) The third class of molecules discussed here are the Ln3+ complexes wherefn⇒ fn transitions are intrinsically two-photon allowed. We have studied two GD3+ single crystals. The CF-splittings, observed clearly in TPA, have been fitted with a parametric model. Some of our observations on the variations of TPA intensity patterns from crystal to crystal, such as circular:linear polarisation ratios, relative intensities of transitions to differentJ-states, do not quite fit in with the Axe-Judd-Downer model. The discrepancies call for a reappraisal of the role of ligand in the TPA process.

    • Author Affiliations

       

      M Chowdhury1 T Chakraborty1 T Kundu1 L Kundu1 A K Banerjee1 D Nath1 S P Bhattacharyya1

      1. Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Calcutta - 700 032, India
    • Dates

       
  • Journal of Chemical Sciences | News

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