  Attosecond chronoscopy typically utilises interfering two-photon transitions
to access the phase information. Simulating these two-photon transitions is
challenging due to the continuum-continuum transition term. The hydrogenic
approximation within second-order perturbation theory has been widely used due
to the existence of analytical expressions of the wave functions. So far, only
(partially) asymptotic results have been derived, which fail to correctly
describe the low-kinetic-energy behaviour, especially for high angular-momentum
states. Here, we report an analytical expression that overcome these
limitations. They are based on the Appell's F1 function and use the confluent
hypergeometric function of the second kind as the intermediate states. We show
that the derived formula can be applied to arbitrarily high angular momenta and
quantitatively agrees with the numerical simulations using the time-dependent
Schr\"odinger equation. Furthermore, we give an angular-momentum-dependent
asymptotic form of the outgoing wavefunction and their continuum-continuum
dipole transition amplitudes.
