Related Experiment Video
Updated: Jul 16, 2026

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Influence of interband transitions on electron-phonon coupling measurements in Ni films
Patrick E Hopkins1, J Michael Klopf, Pamela M Norris
1Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA 22904-4746, USA.
Abstract:
The reduction in size and the increase in speed of opto- and magnetoelectronic devices is making the probability of nonequilibrium electron-phonon phenomena greater, leading to increased thermal resistance in these devices. The measurement of electron-phonon coupling in materials in these devices is becoming increasingly important for accurate thermal management. Here femtosecond thermoreflectance is used to measure the electron-phonon coupling factor in thin Ni films of varying thickness grown on Si and glass substrates. The thermoreflectance response is measured at 1.3 and 1.55 eV, yielding drastically different responses due to the Fermi-level transition at 1.3 eV in Ni. The influence of this transition on the thermoreflectance response results in a measurement of the electron-phonon coupling factor that is twice as high as that recorded in previous measurements that were unaffected by the Fermi-level transition.
Related Concept Videos
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
NMR Spectroscopy: Spin–Spin Coupling
Energy Bands in Solids
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states that no two...
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
Fermi Level
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
π Electron Effects on Chemical Shift: Overview

