High-resolution laser spectroscopy and photodissociation dynamics of OH⁺

Peter J Sarre (1) , David J Rodgers (1) , Andrew D Batey (1)

1 Chemistry

We report high-resolution spectra of the c¹Π - b¹Σ⁺ and c¹Π - a¹Δ electronic transitions of OH⁺ obtained by detecting O and O⁺ photofragments which arise from predissociation of the c¹Π electronic state. Five vibrational bands of the c¹Π - b¹Σ⁺ system and three of the c¹Π - a¹Δ system of ¹⁶OH⁺ were recorded and molecular parameters derived from the analysis. Spectra of the ¹⁶OD⁺ isotopic modification were also taken. A study of perturbations between the A³Π and b¹Σ⁺ states leads to improved determination of the spin-orbit interaction between these states and their relative energies. A selective predissociation mechanism operates with laser excitation to ¹Π (e) levels strongly weighted towards formation of O + H⁺, whereas ¹Π (f) levels yield O⁺ + H exclusively. The predissociation decay rates are also dependent on the c¹Π state vibrational and rotational quantum numbers. The measured linewidths for v′ = 2 and 3 are in good agreement with both a theoretical approach based on spectroscopic parameters and the results of high-quality ab-initio calculations of Yarkony.

Mots clés: Physical Sciences

Peter J Sarre, David J Rodgers, Andrew D Batey. High-resolution laser spectroscopy and photodissociation dynamics of OH⁺. Molecular Physics, 2007, 105 (05-07), pp.849-860. ⟨10.1080/00268970601173041⟩. ⟨hal-00513075⟩