ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The (2+2) resonance-enhanced multiphoton ionization (REMPI) of N2 via the a 1Πg(v=1,J) levels shows a strong dependence on the polarization of the laser beam causing this process. This behavior is attributed to the ac Stark effect produced by the near resonance of the N2 o31Πu(v=0,J) levels with the sum of the first three photons. The multiphoton transitions are broadened and asymmetric in appearance; one level is even split. The line profiles change markedly as the polarization of the laser beam is varied from linear to circular. A general theory is presented for the ac Stark effect in a diatomic molecule undergoing a multiphoton transition. When the sum of the photon energies is resonant with an allowed transition, a splitting of the line is observed (Autler–Townes effect). Off resonance, the magnetic sublevels are shifted by different amounts, causing the line profile to be broadened and distorted. This theoretical treatment is able to explain in a satisfactory manner the observed behavior of (2+2) REMPI of N2 via the a 1Πg–X 1Σ+g transition and the two-photon laser-induced fluorescence of CO via the A 1Π–X 1Σ+ transition.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.463624
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