An infrared pump-probe measurement of the Sm3+6H7/2 lifetime in LiYF4

We report a pump-probe measurement of the lifetime of the 6H7/2 multiplet of Sm3+:LiYF4. A lifetime of 3.1 ± 0.3 ps was inferred for the Y2 level of the 6H7/2 multiplet. This lifetime is two orders of magnitude faster than for a similar energy gap in Nd3+:LiYF4, and does not follow the prediction of a simple exponential energy-gap law for non-radiative relaxation in this material.