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6953867 
Journal Article 
Temperature effects on the formation and the relaxation dynamics of metal-organic interface states 
Szlapa-Kula, A; Malecka, M; Machura, B 
2020 
102 
12 
English 
WOS:000564478000002 
Using time-resolved two-photon photoemission, we systematically study temperature effects on the Shockley-derived unoccupied interface states of perylene- and naphthalene-tetracarboxylic dianhydride (PTCDA and NTCDA) adsorbed on Ag(111). With increasing sample temperatures from 100 to 300 K, we observe a continuous decrease of the interface-state energy by 0.06 and 0.1 eV, respectively, for the two different molecule/metal systems. We relate this energy shift to a molecular lifting off the metal surface. The lifting is accompanied with an increase of the interface-state lifetime from 28 to 53 fs for PTCDA and from 60 to 110 fs for NTCDA. This is in qualitative agreement with the reduction of phase space for electron scattering associated with the thermal energy shift. The magnitude of the experimentally observed lifetime increase, however, is much stronger than would be expected from the energy shift alone. © 2020 American Physical Society.