Abstract
A detailed study of the frequency-resolved spectroscopy technique is presented. We show that the quadrature signal is the convolution of P′(1og τ), the distribution for the logarithm of lifetimes, and a symmetric, sharply peaked “scanning function”. By analysing the low-temperature geminate quadrature frequency-resolved spectra, we find that there are two contributions to P′(1og τ). In addition to the well known ‘geminate peak’ at approximately 2 ms, there is another one close to 1 μs, the latter being attributed to direct competition between thermalization and radiative recombination. A comparison with recent theoretical work of Shklovskii, Fritzsche and Baranovskii shows that hopping theory is difficult to reconcile with the experimental recombination data.