Phase dependence of OD+, HOD+, and H3+ ions released from the deuterated dication of methanol under ω/2ω laser field irradiation

• Selective ionization of oriented methanol by asymmetric laser field.
• Inspection of the dependence of H3+, OD+ and HOD+ fragment ions on the phase of the asymmetric laser field.
• Angular distribution of H3+, OD+ and HOD+ fragment ions.

Multielectron dissociative ionization of gas phase deuterated methanol (CH3OD) molecules under the irradiation of a 30 fs asymmetric two color (ω/2ω) laser field is studied by means of time-of-flight mass spectrometry. The dependence on phase φ between the two laser beams of OD+, HOD+, H3+ fragment ions released from the dissociation of the dication has been investigated. Based on the phase dependence and the recorded angular distributions, it is proposed that the OD+, HOD+ ions can be ejected from fast and slow dissociation processes. The fast dissociation process is attributed to fragmentation from singlet states. The possibility that the slow dissociation process involves a long-lived metastable state and/or dissociation from triplet states is also discussed. The dependence of the H3+ ion on phase φ reveals the existence of two different, as far as the time scale is concerned, stages in its production.

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