Doppler-free two-photon electronic absorption of nitric oxide and benzene

Abstract
Doppler‐free electronic state absorption spectra of molecules have been recorded by means of counterpropagating‐beam two‐photon spectroscopy. The molecular transitions that were investigated were the A2Σ+1(v=0) ←X2Π1/2 (v=0) transition of nitric oxide and the 1B2u1A1g, 1410 transition of benzene. Linewidths observed were less than the Doppler width for each transition.