One-phonon band

Further measurements were performed by these authors in the Faraday geometry for fields up to 30 T. The most notable result was the observation, above 25 T, of a line above the one-phonon band, whose energy increased linearly with the field. It was speculated that this feature was related to the first Landau level of the VB. 

This setup allows one to obtain two types of transient data (i) at fixed tu, the monochromator grating is scanned or (ii) at fixed monochromator frequency, the time delay is changed. Figure 4.13 shows the transient absorption spectra of CO molecules adsorbed on a Pf(lll) surface and obtained for differ-enf fime delays. A distinct shift to lower frequencies and a spectral broadening are observed at small fp as well as the rapid return of the spectrum to the equilibrium lineshape. Such temporal behavior can be described as originating from a one-phonon band of fhe adlayer which shiffs with the increasing excited-state population. 

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