Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments
In the majority of experiments targeting nonlinear optical phenomena, the application of high-intensity pulses drives electrons in graphene into a strongly non-equilibrium state. Under these conditions, conventional perturbation theory falls short in explaining graphene’s intricate optical response...
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| Format: | Article |
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MDPI AG
2024-02-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/14/3/1250 |
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| author | Diogo F. P. Cunha Rui Dias Manuel J. L. F. Rodrigues Mikhail I. Vasilevskiy |
| author_facet | Diogo F. P. Cunha Rui Dias Manuel J. L. F. Rodrigues Mikhail I. Vasilevskiy |
| author_sort | Diogo F. P. Cunha |
| collection | DOAJ |
| description | In the majority of experiments targeting nonlinear optical phenomena, the application of high-intensity pulses drives electrons in graphene into a strongly non-equilibrium state. Under these conditions, conventional perturbation theory falls short in explaining graphene’s intricate optical response because of significant deviations in electron distribution over energy states from the equilibrium Fermi-Dirac one. In this work, we present a two-step relaxation model capable of predicting the transient dynamics of graphene’s carriers out of equilibrium, from the generation of spectrally narrow populations of non-thermalized electrons and holes to the establishment of a hot-electron gas and its subsequent cooling toward equilibrium with the crystal lattice. By comparing our model calculations to experimental results, we demonstrate its reliability and relevance to pump–probe experiments, providing insights into the pivotal role of hot electrons in comprehending ultrafast dynamics in graphene. |
| first_indexed | 2024-03-08T04:00:51Z |
| format | Article |
| id | doaj.art-b5ea18377dc44935b15d6a733c40b000 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-08T04:00:51Z |
| publishDate | 2024-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-b5ea18377dc44935b15d6a733c40b0002024-02-09T15:08:23ZengMDPI AGApplied Sciences2076-34172024-02-01143125010.3390/app14031250Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe ExperimentsDiogo F. P. Cunha0Rui Dias1Manuel J. L. F. Rodrigues2Mikhail I. Vasilevskiy3Centre of Physics—CF-UM-UP and Laboratório de Física para Materiais e Tecnologias Emergentes (LaPMET), University of Minho, Campus of Gualtar, 4710-374 Braga, PortugalCentre of Physics—CF-UM-UP and Laboratório de Física para Materiais e Tecnologias Emergentes (LaPMET), University of Minho, Campus of Gualtar, 4710-374 Braga, PortugalCentre of Physics—CF-UM-UP and Laboratório de Física para Materiais e Tecnologias Emergentes (LaPMET), University of Minho, Campus of Gualtar, 4710-374 Braga, PortugalCentre of Physics—CF-UM-UP and Laboratório de Física para Materiais e Tecnologias Emergentes (LaPMET), University of Minho, Campus of Gualtar, 4710-374 Braga, PortugalIn the majority of experiments targeting nonlinear optical phenomena, the application of high-intensity pulses drives electrons in graphene into a strongly non-equilibrium state. Under these conditions, conventional perturbation theory falls short in explaining graphene’s intricate optical response because of significant deviations in electron distribution over energy states from the equilibrium Fermi-Dirac one. In this work, we present a two-step relaxation model capable of predicting the transient dynamics of graphene’s carriers out of equilibrium, from the generation of spectrally narrow populations of non-thermalized electrons and holes to the establishment of a hot-electron gas and its subsequent cooling toward equilibrium with the crystal lattice. By comparing our model calculations to experimental results, we demonstrate its reliability and relevance to pump–probe experiments, providing insights into the pivotal role of hot electrons in comprehending ultrafast dynamics in graphene.https://www.mdpi.com/2076-3417/14/3/1250graphenehot electronspump–probe spectroscopynonlinear optics |
| spellingShingle | Diogo F. P. Cunha Rui Dias Manuel J. L. F. Rodrigues Mikhail I. Vasilevskiy Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments Applied Sciences graphene hot electrons pump–probe spectroscopy nonlinear optics |
| title | Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments |
| title_full | Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments |
| title_fullStr | Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments |
| title_full_unstemmed | Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments |
| title_short | Two-Step Relaxation of Non-Equilibrium Electrons in Graphene: The Key to Understanding Pump–Probe Experiments |
| title_sort | two step relaxation of non equilibrium electrons in graphene the key to understanding pump probe experiments |
| topic | graphene hot electrons pump–probe spectroscopy nonlinear optics |
| url | https://www.mdpi.com/2076-3417/14/3/1250 |
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