Mode selective photodissociation dynamics in V+(OCO)

Area of Science:

• Physical Chemistry
• Chemical Physics
• Spectroscopy

Background:

• The electrostatic V+(OCO) complex exhibits a vibrationally resolved photodissociation spectrum.
• Photodissociation yields both nonreactive (V+ + CO2) and reactive (VO+ + CO) pathways.
• VO+ production is energetically favored but spin-forbidden.

Purpose of the Study:

• Investigate mode selectivity in the photodissociation of V+(OCO).
• Explore the influence of specific vibrational modes, particularly the OCO antisymmetric stretch, on reactivity.
• Characterize dissociation pathways and excited electronic states using computational methods.

Main Methods:

• One-photon and vibrationally mediated photodissociation spectroscopy.
• Excitation of specific vibrational modes including OCO antisymmetric stretch, CO2 bend, V+(OCO) stretch, and rock.
• Electronic structure calculations using hybrid density functional theory (DFT) and coupled cluster methods.
• Time-dependent DFT for excited states and spin-orbit coupling calculations.

Main Results:

• One quantum of rocking motion enhances VO+ production by over 30%.
• Exciting the OCO antisymmetric stretch increases the reactive VO+ channel by approximately 15%.
• Combination bands involving the antisymmetric stretch also show slightly enhanced reactivity.
• Calculated intersystem crossing rates correlate with observed mode-selective trends.

Conclusions:

• Vibrational excitation, especially of the OCO antisymmetric stretch and V+--OCO stretch, enhances the spin-forbidden reactive channel.
• Intersystem crossing rates are crucial for understanding the observed mode selectivity in V+(OCO) photodissociation.
• Computational and experimental results provide insights into the dynamics of reactive collisions involving metal ion complexes.