Lifetime vibrational interference during the NO 1s^{1π ^ast} resonant excitation studied by the NO^+(A ^1Pi → X ^1Σ^+) fluorescence
Abstract
Dispersed fluorescence from fragments formed after the deexcitation of the 1s^{1}π ^{ast} resonances of N^{ast}O and NO^{ast} has been measured in the spectral range of 118 142 nm. This range is dominated by lines of atomic nitrogen and oxygen fragments and by the A ^{1}Pi ≤ft(v^{prime}right) → X ^{1}Σ^{+}≤ft(v^{prime prime}right) bands in the NO^{+} ion which result from the participator Auger decay of the 1s^{1}π ^{ast} resonances. Abinitio calculations of the transition probabilities between vibrational levels during the reaction NO X ^{2}Pi≤ft(v_{0}=0right) → N^{ast }O≤ft( NO^{ast}right) 1s^{1}π ^{ast }≤ft( v_{r}right) Longrightarrow NO^{+} A ^{1}Pi ≤ft(v^{prime}right) → X ^{1}Σ^{+}≤ft(v^{prime prime}right) were used to explain the observed intensity dependence for the A≤ft(v^{prime }right) → X≤ft(v^{prime prime}right) fluorescence bands on the excitingphoton energy across the resonances and on both v^{prime} and v^{prime prime} vibrational quantum numbers. The multiplet structure of the 1s^{1}π ^{ast} resonance and lifetime vibrational interference explain the observed excitingphoton energy dependence of the A≤ft( v^{prime}right) → X≤ft(v^{prime prime}right) fluorescence intensity. A strong spinorbit coupling between singlet and triplet states of NO^{+} is proposed to reduce additional cascade population of the A ^{1}Pi state via radiative transitions from the W ^{1}Δ and A^{prime} ^{1}Σ^{} states and to explain remaining differences between measured and calculated integral fluorescence intensities.
 Publication:

European Physical Journal D
 Pub Date:
 November 2007
 DOI:
 10.1140/epjd/e2007002746
 Bibcode:
 2007EPJD...45..235E