Temperature evolution of infrared- and Raman-active phonons in graphite

We perform a comparative experimental and theoretical study of the temperature dependence up to 700 K of the frequency and linewidths of the graphite E-1u and E-2g optical phonons (similar to 1590 and 1580 cm(-1)) by infrared (IR) and Raman spectroscopy. Despite their similar character, the temperature dependence of the two modes is quite different, e. g., the frequency shift of the IR-active E-1u mode is almost twice as big as that of the Raman-active E-2g mode. Ab initio calculations of the anharmonic properties are in remarkable agreement with measurements and explain the observed behavior.