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HRTEM images and diffraction pattern of as-deposited 5 nm thick Bi film (a) and laser annealed sample at laser fluence of 2.4 mJ/cm2 operated at 1 kHz repetition rate (b). Laser annealing causes some agglomeration of the as-deposited islands and an increase of voids. The diffraction patterns are characteristic of the bulk hexagonal unit cell, indicating no structural phase transition occurring during annealing. The ring intensities change by annealing indicating changes in film orientation.
(Color online) Time evolution of Bragg peak normalized intensity. (a) For the (012) planes, the decay time τ is 11.2 and 4.1 ps for laser fluence of 1.5 and 3.3 mJ/cm2, respectively. (b) For the (110) planes, τ is 4.3 and 3.1 ps for laser fluence of 1.5 and 3.3 mJ/cm2, respectively. Anisotropy in the decay time of the (012) and (110) peaks indicates different lattice excitation mechanisms that is dependent on crystal direction.
(Color online) Diffraction width of the (012) Bragg peak normalized to that without laser heating taken at delay time 41 ps for different laser fluences. Inset is time evolution of normalized Bragg peak width at two different laser fluences.
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