Evidence for Two Superconducting Gaps in $Mg{B}_2$

X. K. Chen, M. J. Konstantinovic, J. C. Irwin +2

We have measured the Raman spectra of polycrystalline MgB${}_2$ from 25 {\cm} to 1200 {\cm}. When the temperature was decreased below the superconducting transition temperature $T_…