  Developing effective methods to measure the enantiomeric excess of the chiral
mixture is one of the major topics in chiral molecular researches, yet remains
challenging. Enantiodetection method via two-dimensional (2D) spectroscopy
based on a four level model, containing a cyclic three-level system (CTLS), of
chiral molecules was recently proposed and demonstrated, yet with a strict
condition of the one-photon resonance (where three driving fields are exactly
resonantly coupled to the three electric-dipole transitions, respectively) in
the CTLS and narrowband probe pulse assumption. Here, we extend the 2D
spectroscopy method to more general experimental conditions, with three-photon
resonance (where the sum of the two smaller frequencies among the three driving
fields equals to the third one) and broadband probe pulse. Our method remains
effective on enantiodetection with the help of experimental techniques, such as
the chop detection method, which is used to eliminate the influence of the
other redundant levels existing in the real system of chiral molecules. Under
these more general conditions, the enantiomeric excess of the chiral mixture is
estimated by taking an easily available standard sample (usually the racemic
mixture) as the reference.
