HARMONIC-ANALYSIS OF PHONON ECHOES IN LIQUIDS

We present, for the first time, a study comparing phonon quench echoes in supercooled liquid argon with a normal mode analysis of the echoes. The phonon echoes are produced via molecular dynamics simulation. We model the echoes by considering a collection of harmonic oscillators whose frequency distribution is defined by the density of normal modes in the liquid under consideration. We find for times less than 300 fs, the fluid behaves in a relatively harmonic manner. We also find that low temperatures and short times are best suited to harmonic analysis. We comment on the agreement and deviation between simulation and model particularly as dephasing processes are concerned. Future approaches to this phenomenon are addressed as well.