Femtosecond Probe Catches Electrons Relaxing
February 10, 2021•
H.-T. Chang
H.-T. Chang
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After being excited by a light pulse, energy carriers in a material scatter off one another to form a hot thermal distribution before relaxing back to equilibrium. Picking apart how these thermalization and relaxation processes occur on ultrashort timescales has been a goal for decades, as they are inherent to phenomena ranging from energy harvesting in solar cells to demagnetization. Hung-Tzu Chang, at the University of California, Berkeley, and his colleagues have now measured the time taken for electrons to thermalize and then cool in a femtosecond-resolution experiment [1]. Such observations are vital to the design of metals and semiconductors for applications in photovoltaics and photocatalysis.