Anomalous dispersion of adsorbate phonons of Mo(110)-H

The dispersion curve of the longitudinal-optical adsorbate phonon on hydrogen-saturated Mo(110) along [001] is found to exhibit an anomalous indentation. The maximum indentation is observed at a wave vector, which coincides within the experimental angular resolution with the wave vector, at which the known giant Kohn anomaly for the transverse- and longitudinal-acoustic substrate surface phonons along [001] occurs