Haiwang Yong

TL;DR: In this paper, the authors observed a substantial acceleration of the ring-opening motion after internal conversion to the ground state due to steepening of the electronic potential gradient towards the product minima and demonstrated the potential of megaelectronvolt ultrafast electron diffraction to elucidate photochemical reaction paths in organic chemistry.

TL;DR: The photochemical electrocyclic ring-opening of 1,3-cyclohexadiene is a textbook organic chemistry reaction that is resolved on the level of atomic distances and on its natural femtosecond timescale using megaelectronvolt ultrafast electron diffraction.

TL;DR: Ultrafast X-ray scattering combined with a detailed structural determination analysis precisely measures the coherent vibrational motions of a polyatomic organic molecule following photoexcitation.

TL;DR: It is shown that the initially excited electronic state can be determined using the anisotropic component of ultrafast time-resolved X-ray scattering signals and is identified as the 3p z Rydberg state, thus bypassing the need for further experimental studies to determine the starting point of the photoinduced dynamics and clarifying inconsistent computational results.

TL;DR: A direct measurement of the initial redistribution of electron density when the molecule 1,3-cyclohexadiene (CHD) is optically excited is reported, which is a fundamental process that leads to changes in the electron density in matter.