The driving force leading to the charge-density-wave (CDW) phase transition in 1T-TiSe2 is still highly debated. Among the proposed mechanisms, the excitonic insulators model, i.e. the Coulomb interaction between holes of the valence band and electrons in the conduction band, has gained major attention thanks to recent time-resolved experiments [1,2]. However, lattice distortion and electron-lattice interaction also play an important role, as suggested by theoretical calculations [3,4]. We employed femtosecond time- and angle-resolved photoemission spectroscopy to investigate the photo-induced melting of CDW in 1T-TiSe2 single crystals. Our measurements reveal that spectral weight and energy position of the valence band undergo different dynamics after photo-excitation with ultrashort visible laser pulses. This discrepancy is analyzed in the contest of the excitonic model and the band-type Jahn-Teller mechanism.
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