Title: Vibrational heating and photodissociation of admolecules induced by plasmonic hot carriers

Abstract: The hot carriers generated by plasmon damping hold significant potential for photoelectric conversion and photocatalysis. Despite numerous experiments and theoretical analyses, the precise role of plasmonic hot carriers in such dynamical processes has not been well understood. Here we present a theory of plasmonic photocatalysis based on the microscopic model of electron-vibrational coupling and the vibrational heating mechanism. The nonthermal hot carrier distribution was derived and treated on equal footing with the thermal Fermi-Dirac distribution. The inelastic rates of vibrational excitations were calculated including the effect of multiple electronic transitions. As an example of application, the O$_2$ dissociation on silver nanoparticles was explored with focus on the temperature- and light-intensity dependences. The dissociation rate evolves from a linear regime into a superlinear regime due to the onset of vibrational heating induced by hot carriers. In the nonlinear regime, nonthermal hot carriers greatly promote molecular dissociation. Our findings provide insight into plasmonic photocatalysis, and paves the way for harnessing light energies in the nonthermal regime.