Cavity ring-down observation of Yb(3+) optical absorption in room temperature solution.

Cavity ring-down spectroscopy is used to probe the optical absorption of the optical pseudo-two level system [Xe]4f(13) Yb(3+) in room temperature solution, a situation where the two-color pump-probe luminescence approach commonly used to study the other [Xe]4f(n) (2 < or = n < or = 12) trivalent lanthanide ions fails. A 1m optical cavity constructed from two highly reflective mirrors is used to obtain ring-down signals as a function of wavelength from 1 mL samples contained in a quartz cuvette placed in the center of the cavity. Absorption spectra constructed from these signals characteristic of the (6)H(15/2)-->(4)F(9/2) [Xe]4f(5) Dy(3+) and the (7)F(0)-->(5)D(0) [Xe]4f(6) Eu(3+) transitions are presented and compared to the corresponding single pass absorption and two-color pump-probe luminescence spectra to obtain sensitivity estimates. Finally the spectrum for the (2)F(5/2)-->(2)F(7/2) [Xe]4f(13) Yb(3+) transition for a model Yb(3+) complex in room temperature solution is obtained using cavity ring-down spectroscopy for the first time.