Optical study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>RbV</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Sb</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math> : Multiple density-wave gaps and phonon anomalies

Temperature-dependent reflectivity studies on the nonmagnetic kagome metal ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ in a broad energy range ($50--20000{\mathrm{cm}}^{\ensuremath{-}1}$, equivalent to 6 meV--2.5 eV) down 10 K are reported. Below ${T}_{\mathrm{CDW}}=102$ K, optical spectra demonstrate prominent spectral-weight transfer from low higher energies as fingerprint of charge-density-wave (CDW) formation with opening partial gap. A detailed analysis reveals two scales respectively $\ensuremath{\sim}800 {\mathrm{cm}}^{\ensuremath{-}1}$ (100 meV) and $360{\mathrm{cm}}^{\ensuremath{-}1}$ (45 meV), latter visible below 50 only. Additionally, modes at $160{\mathrm{cm}}^{\ensuremath{-}1}$ (20 $430{\mathrm{cm}}^{\ensuremath{-}1}$ (53 can be traced both above ${T}_{\mathrm{CDW}}$. They show strong anomalies already ${T}_{\mathrm{CDW}}$ further renormalization across transition, suggesting importance electron-phonon coupling normal CDW states. While mode attributed ${E}_{1u}$ phonon, could not reproduced our phonon calculations. The antiresonance nature this suggests nontrivial ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$. distinct localization peak observed all temperatures signals damped electron dynamics, whereas reduced Drude spectral weight manifests moderate deviations band picture