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The influence of alpha clustering on nuclear reaction dynamics is investigated using the giant dipole resonance (GDR) lineshape studies in the reactions 20 Ne (E lab =145,160 MeV) + 12 C and 20 Ne (E lab =160 MeV) + 27 Al , populating 32 S and 47 V, respectively. The GDR lineshapes from the two systems are remarkably different from each other. Whereas, the non alpha-like 47 V undergoes Jacobi shape transition and matches exceptionally well with the theoretical GDR lineshape estimated under the framework rotating liquid drop model (RLDM) and thermal shape fluctuation model (TSFM) signifying shape equilibration, for alpha cluster 32 S an extended prolate kind of shape is observed. This unusual deformation, seen directly via γ-decay for the first time, is predicted to be due to the formation of orbiting di-nuclear configuration or molecular structure of 16 O+ 16 O in 32 S superdeformed band.

The systematic evolution of the giant dipole resonance (GDR) width in the temperature region of 0.9 ∼ 1.4 MeV has been measured experimentally for 119 Sb using alpha induced fusion reaction and employing the LAMBDA high energy photon spectrometer. The temperatures have been precisely determined by simultaneously extracting the vital level density parameter from the neutron evaporation spectrum and the angular momentum from gamma multiplicity filter using a realistic approach. The systematic trend of the data seems to disagree with the thermal shape fluctuation model (TSFM). The model predicts the gradual increase of GDR width from its ground state value for T > 0 MeV whereas the measured GDR widths appear to remain constant at the ground state value till T ∼ 1 MeV and increase thereafter indicating towards a failure of the adiabatic assumption of the model at low temperature.

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