Valence (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>1</mml:mn></mml:msub></mml:math>) and nonvalence (dipole-bound) spectroscopy of chromophore models of the photoactive yellow pr

The authors present a high-resolution spectroscopic characterization of deprotonated para-coumaric acids, probing specifically electronic excitations near threshold. The results provide insight into the dynamics of electron capture and release in dipole-bound systems, relevant for modeling processes in both interstellar environments and biological systems.