2026-10-11T07:02:45Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34046337 2026-10-01T14:25:51Z category_915 category_873 category_45 category_734 portal_63 item_type_6 month_year_10_2026

Excitation-Energy-Dependent Enhancement of Hot-Carrier Lifetimes in Graphene Sachin Sharma (25799) Elliott Walker (25156986) Rachael Myers-Ward (20551907) Jenifer Hajzus (20551904) Yijing Liu (1847053) Paola Barbara (8668284) Ioannis Chatzakis (1587409) Physical Sciences not elsewhere classified Chemical Sciences not elsewhere classified Sociology Biological Sciences not elsewhere classified provide new insight narrow spectral window infrared pump pulses terahertz probe pulses previously unreported excitation higher excitation energies carrier lifetime increases picosecond cooling observed phonon bottleneck scenario carrier relaxation time excitation photon energy graphene understanding hot phonon bottleneck observed excitation carrier relaxation carrier cooling terahertz technologies carrier lifetimes ultrafast optoelectronic nonmonotonic dependence magnitude compared findings reveal energy transfer energy dependence dependent enhancement 73 ev 48 ev Understanding hot-carrier relaxation in graphene is important for ultrafast optoelectronic and terahertz technologies. Here, we investigate carrier cooling dynamics in mono- and bilayer graphene using mid-infrared pump pulses (0.22 to 0.73 eV) and terahertz probe pulses. We uncover a pronounced, reproducible, and nonmonotonic dependence of the carrier relaxation time on excitation photon energy. Within a narrow spectral window from 0.42 to 0.48 eV, the carrier lifetime increases by nearly an order of magnitude compared to the few-picosecond cooling observed at lower and higher excitation energies. The observed excitation-energy dependence is consistent with a hot-phonon bottleneck scenario in which the accumulation and reabsorption of nonequilibrium optical phonons suppress the energy transfer to the lattice. A phenomenological coupled carrier–phonon model supports this interpretation. These findings reveal a previously unreported excitation-energy dependence of hot-carrier cooling in graphene and provide new insight into nonequilibrium carrier–phonon interactions near the optical-phonon bottleneck. 2026-10-01T00:00:00Z Text Journal contribution 10.1021/acsphotonics.6c01679.s001 https://figshare.com/articles/journal_contribution/Excitation-Energy-Dependent_Enhancement_of_Hot-Carrier_Lifetimes_in_Graphene/34046337 CC BY-NC 4.0