  We reported two-magnon Raman scattering from La_{1.9}Sr_{0.1}CuO_4, which has
a suppressed Tc=12 K, as the temperature is lowered below 37 K and an ordered
spin phase is formed. The two-magnon Raman intensity increases with decreasing
temperature. The magnetic scattering in La_{1.9}Sr_{0.1}CuO_4 is totally
different from that reported in the parent compound La_2CuO_4. We analyze the
line shape of the two-magnon scattering within the traditional Loudon-Fleury
theory and find the superexchange constant J=1052 cm^{-1}. The calculation of
the frequency moment suggests that the quantum fluctuations are very weak in
the system. The room temperature Raman scattering from La_2CuO_4 is also
measured. Strong features appear in the one-phonon spectrum at the frequencies
of the longitudinal optical (LO) infrared modes which we suggest become Raman
active through a Fr\"{o}hlich-interaction.
