This combination mode is probably so effective because it combines student engagement through peer discussion with instructor feedback.
Stuecker, M. F., Jin, F.-F., Timmermann, A. & McGregor, S. Combination mode dynamics of the anomalous northwest Pacific anticyclone.
As depicted in the inset of Fig. 2c, the LOZO′ combination mode relates to a q ≈ 2k AV process.
The system was designed to operate under infrared, hot air and combination mode independently.
The renormalization will happen independently for each phonon, so that, as a first approximation for a combination mode or overtone, the renormalization will be Π ωLO+j, EF) = Π ωLO, EF +Π(ωj, EF), where j is a LO mode if an overtone is considered or j is a ZO, ZO′ and ZA if a combination mode is considered.
In analogy to the LOZO′ combination mode about the Γ-point, the 2LO overtone is a q≈ 2k AV double resonant process and is a fruitful choice for unraveling the two-phonon self-energy contributions that are merged in the LOZO′ combination mode.
It is also important to say that, from Fig. 1c, at higher EL (4.15 eV according to our observations) the LOZA combination mode might cross the LOZO′ mode too.
By following the same strategy, we could also estimate the phonon self-energy corrections for the ZA mode, whose LOZA combination mode frequency (linewidth) also hardens (broadens) as expected for q ≠ 0 AV processes.
In other words, the two peaks, LOZO′ and LOZO′ observed in the Raman spectra, come from the same phonon combination mode LOZO′ but probed at two different points of its phonon dispersion8.
