Figure 1.

(a) Schematic of the excitation scheme used to measure TR-PECD from the 3s Rydberg state of fenchone. The HOMO and the 3s orbitals are drawn to illustrate the difference in the initial wave function of the outgoing electron. (b) The photoelectron images recorded on (1R)-(−)-fenchone (e = −1) for each probe helicity (LCP-p = 1 or RCP-p = −1) are subtracted one from the other (LCP – RCP) to extract the unnormalized odd Legendre polynomial coefficients, while the sum of these images (LCP + RCP) provides the photoelectron spectrum (PES). These (LCP – RCP) and (LCP + RCP) images, called “difference” and “sum” images, respectively, are shown for three pump–probe delays. Note that the two photon beams are quasi copropagating with polarization axis parallel to the detector (see the Supporting Information).