Gold Nanorods as a High-Pressure Sensor of Phase Transitions and Refractive-Index Gauge

<div>The absorption peaks of surface plasmon resonance (SPR) in Au NRs are highly sensitive to their surrounding medium and to its refractive index (<i>RI</i>) changes. However, no applications of NRs for detecting phase transitions have been reported. Here we show that Au NRs effectively detect phase transitions of compressed compounds, liquid and solid, by measuring their <i>RI</i>. Owing to the direct interaction of the NRs with their surrounding medium, its subtle <i>RI</i> changes can be observed by the use of high-pressure absorption Vis-NIR spectroscopy.</div><b></b>