Coherent optical phonons in pure and Pr3+ doped YAG crystal studied by Optical Kerr Effect spectroscopy: Temperature and concentration dependence

Large polarons in lead halide perovskites

“…1A ). We see that the broad and featureless nuclear response is distinctively different from that of a typical solid, where impulsively stimulated Raman excitation should appear as oscillatory features ( 28 ), and is instead characteristic of liquids ( 26 , 27 ). The absence of oscillatory features suggests that we detect predominantly overdamped phonon modes that can be attributed to strong anharmonicity and dynamic disorder ( 29 , 30 ).…”

“…When hν 1 (=1.83 or 2.00 eV) is far below E g , the OKE signal consists of two responses: a broad feature within ~0.3 ps and an oscillatory response distributed over a few picoseconds ( Fig. 2A ); the former is liquid-like ( 26 , 27 ), whereas the latter is Raman-active vibrations typical of solids ( 28 ). The corresponding Fourier spectra in Fig.…”

Lead halide perovskites: Crystal-liquid duality, phonon glass electron crystals, and large polaron formation

“…This technique has been used in the past to probe liquids, particularly diffusive reorientation dynamics on picosecond time scales ( 47 , 48 ). In a crystalline solid, the TR-OKE transient is typically dominated by the ultrafast and nearly instantaneous electronic polarization, plus weaker coherent oscillations attributed to impulsively stimulated Raman excitation of phonons ( 49 ). The TR-OKE responses in Fig.…”

Carrier and exciton dynamics in halide perovskites

“…ultrafast response, plus weak coherent oscillations attributed to Raman active phonon modes[93]. HOIPs are called crystalline liquids by Zhu et al due to the coexistence of a crystalline-like response of charge carriers and a liquid-like response in the phonon response[94].…”